Olfactory bulb infection. Infections could cause meningitis.
Olfactory bulb infection Participants with post-acute self-reported olfactory dysfunction had a significantly lower olfactory bulb volume at baseline than normally smelling individuals. The main outcome measures for the study were the severity of degeneration to neurons in the olfactory system, the loss of olfactory axons, and the severity of The trauma may also directly damage the olfactory bulb that detects the molecules we smell. The initial step in SARS-CoV-2 infection is attachment to the a Development of a novel peptide to prevent entry of SARS-CoV-2 into lung and olfactory bulb cells of hACE2 expressing mice Mol Brain. Red cells Although various environmental agents induce inflammation in different ways via distinct cellular and molecular interactions, nasal inflammation has similar consequences on the structure and homeostatic function of the olfactory bulb (OB) which is the first relay center for olfactory information in the brain. The aim of our study wa Right, 30 d following electroporation, pseudotyped SADΔG-EGFP RV was injected into the olfactory bulb for targeted infection of electroporated granule cells. ORs are also expressed peripherally (e. For example, HSV-1 inoculated into the rat olfactory bulb ultimately infects cholinergic neurons in the horizontal limb of the Furthermore, injury to the nasal epithelium resulted in increased peripheral nerve and olfactory bulb infection, but did not alter general CNS infection. We examined the histopathological changes in the olfactory mucosa of cynomolgus and rhesus macaque models of SARS-CoV-2 infection. A fetus only has Interneurons of the olfactory bulb survive rJ infection. Herpes simplex virus-1 infects the olfactory bulb shortly following ocular infection and exhibits a long-term inflammatory profile in the form of effector The olfactory neuronal infection by WA1 and the subsequent olfactory bulb transport via axon were more pronounced in younger hosts. In comparison, the olfactory bulb volumes on the MRI after COVID-19-induced anosmia were 29·96 mm 3 and 35·51 mm 3, smaller than the minimum olfactory bulb volume in the literature of 54 mm 3 in women < 45 years Ginkel and co-workers demonstrated that intranasal injection of a strain of Streptococcus pneumonia, which is non-viable in the blood system, resulted in olfactory bulb and CNS infection via olfactory axonal transport after just 24 h . (Fig. Clinical trials and prospective and histological studies of The olfactory bulb is a unique brain structure directly connected with the external world through the olfactory nerve coming from the nasal epithelium. Surgical removal of the olfactory bulb alters several aspects of immunological activity. Figure 1. Study design: Retrospective study of 26 patients with postinfectious olfactory loss. This review summarizes the impact of nasal inflammation on the morphological and physiological features of the rodent OB. , COVID-19) or eLife assessment. Citation: Li Y, Liu M, Zhang R, Wang Y and Liu J (2025) Long COVID-19–related and non-COVID-19 Consequences of SARS-CoV-2 infection on the olfactory bulb. Brain Tumors: Both malignant and benign brain tumors, especially those which involve the olfactory bulb or the temporal Supporting cells and olfactory neurons were infected, and SARS-CoV-2 N protein was detected in the axons of olfactory neurons and in olfactory bulbs. 1007 In the autopsy cases examined, it was found that there was a significant decrease in bilateral olfactory bulb (OB) and olfactory tract (OT) volumes in COVID-19 group (p < 0. In addition, the observed viral clearance delay and phagocytic dysfunction in aged olfactory mucosa were accompanied by a decline of phagocytosis-related genes. This study investigated the role of the olfactory bulbs in the control of behavioral responses to simulated infection, and the environmental modulation of sickness behaviors by changes in day length. Detection of mouse-adapted human influenza virus in the olfactory bulbs of mice within hours after intranasal infection J Neurovirol or no anesthesia. 32 In this study, we also found SARS-CoV-2 viral protein in hippocampus, thalamus, entorhinal area, and medulla oblongata post intranasal inoculation (Fig. The infection with the rabies virus was detected in the OB after 80 hours p. 0% at baseline examination and 17. Recently, the olfactory area—a site containing the olfactory receptor cells responsible for odor perception—was shown to harbor a complex microbiome that reflects the state of olfactory function. 6 MRI studies exhibit a correlation between bulb size and olfactory dysfunction, reflecting a lower sensory activity in New loss of smell (anosmia/hyposmia) is now recognized as a COVID-19 related symptom, which may be caused by SARS-CoV-2 infection and damage of the olfactory receptor (OR) cells in the nasal neuroepithelium and/or central involvement of the olfactory bulb. Changes in olfactory bulb volume and olfactory sulcus depth in COVID-19 infection: an autopsy study Eur Arch Otorhinolaryngol. MR imaging can provide anatomic data about the olfactory pathway. The infection of olfactory neurons was thought to be through pneumococci interaction with gangliosides . The olfactory bulb (OB) is the first brain structure that receives information about odors from the nasal epithelium. The olfactory bulb (OB) is considered an immunologic organ that shields the CNS from viral infection, so its involvement could risk the CNS being subjected to infection. , 2001). Normally, microbes are prevented from infecting the olfactory mucosa through sneezing, clearing of mucous, immune responses by cells in the nasal mucosa or apoptosis of infected cells [1, 2]. Methods: One hundred patients with olfactory dysfunction after upper respiratory tract infection (patient group) were compared with one hundred normal controls in terms of BACKGROUND: Genesis and the prognostic value of olfactory dysfunction (OD) in COVID-19 remain partially described. This study presents a useful description of transcriptional responses in adult zebrafish olfactory bulb microglia and neurons following exposure to infectious hematopoietic necrosis virus. Researchers from a 2021 study found that infection from SARS-CoV-2, the virus that causes COVID-19, can cause damage to the The metabolic impairment of the olfactory bulbs is an important phenomenon to consider for further therapeutic interventions. Yet, there is only vague understanding of how these aspects relate Olfactory bulb volume at baseline was significantly lower in individuals that exhibited self-reported olfactory dysfunction during both examination timepoints but not during the acute infection. In addition, the observed viral clearance delay and phagocytic dysfunction in aged olfactory mucosa is accompanied by a decline of phagocytosis related genes. E. experimental study. Olfactory bulbs: upon entering the brain, the axons synapse with mitral and tufted cells in the olfactory bulbs within glomeruli. It plays an important role in the neurogenesis in the adult mammalian brain. This initially observed correlation between microbiome composition and olfactory performance needed to be confirmed using a larger study cohort The patient’s most recent olfactory bulb volumes measured 3 years before COVID-19-induced anosmia were 49·5 mm 3 and 47·46 mm 3. In the future it would be interesting to assess the OB damage of congenital CMV infection in retrospective and prospective MRI studies. to determine the impact of SARS-CoV-2 infection on the olfactory system, groups of 6–8-week-old hACE2 mice were intranasally infected with 5. Infections could cause meningitis. Introduction. Objective: To analyze the correlation between olfactory bulb (OB) volume, depth of olfactory sulcus (OS) and olfactory function in patients with olfactory dysfunction after upper respiratory tract infection. Radiological evaluation were assessed at early phase of COVID-19 infection because to date no published Microglia in the olfactory bulb have a nose for protecting the brain from infection June 5 2020 Scanning electron micrograph of a human T lymphocyte (also called a T cell) We found that the olfactory bulb (OB) and tract were the initial areas of CNS virus infection in mice. Some neurons within the olfactory bulb strongly expressed tdTomato throughout the Olfactory bulb volume at baseline was significantly lower in individuals that exhibited self-reported olfactory dysfunction during both examination timepoints but not during the acute infection. Thus, different cell types might exert specific immune response in different sections of the brain. Herpes simplex virus-1 infects the olfactory bulb shortly following ocular infection and exhibits a long-term inflammatory profile in the form of effector Abstract. Phillips ported on conventional neuroimaging and may serve as a noninvasive biomarker of infection. Here we analyzed differential gene and protein expression in the olfactory bulb (OB) and tract (OT) of familial AD (FAD) individuals carrying the autosomal dominant presenilin 1 E280A mutation. As expected, given the cellular tropism of rJ, most surviving tdTomato-positive cells were neurons, as demonstrated morphologically and confirmed by NeuroTrace (Thermo Fisher Scientific) staining (Fig. Since the OB was susceptible to infection, and infected However, the absence of virus within the neural and glial compartments in olfactory bulb samples, as well as in olfactory tubercles/lateral olfactory tract/medial olfactory tract, along with the endothelial localisation of the virus in such samples, seem to indicate that the virus spreads through a haematogenous route, which could be related to Although the olfactory bulb can effectively control viral entry into the CNS, [55] coronaviruses can enter the brain through the olfactory mucosa and olfactory tract during the early infection Consequences of SARS-CoV-2 infection on the olfactory bulb. Temporary anosmia may occur due to upper respiratory infection (e. , 2008 , Harkema et al. The Sense Of Smell. COVID-19-related anosmia has been associated with viral persistence and inflammation in human olfactory epithelium and brain infection in hamsters . SARS-CoV-2 infection induced severe inflammatory changes in the olfactory mucosa. 44 A local disease Upon intranasal vesicular stomatitis virus infection, astrocytes in the olfactory bulb are important interferon Beta producers that protect from lethal encephalitis IFN-β responses mounted by astrocytes within the olfactory bulb critically contribute to the antiviral defense by stimulating distal IFN-β-negative brain areas and thus Numerous pathogens can infect the olfactory tract, yet the pandemic caused by SARS-CoV-2 has strongly emphasized the importance of the olfactory mucosa as an immune barrier. In vitro, C. The aim of our study was to observe alterations of central olfactory pathways in Despite this, a reduction in olfactory bulbs was described in 36 participants who had COVID-19 olfactory dysfunction compared to a control group 2 to 8 weeks after infection 13, and in 196 The main olfactory bulb's pulses in the amygdala are used to pair odors to names and recognize odor to odor differences. We may expect some structural changes in the olfactory bulb so we evaluated our patient with cranial imaging. In anosmic patients, SARS-CoV-2 temporarily alters the signaling process in olfactory nerve cells and olfactory bulb (OB), which eventually damages the structure of the olfactory epithelium, leading to a permanent disorder in the olfactory pathway that this damaged In this review, we will discuss the actual knowledge regarding olfactory bulb function, practical ways to measure olfactory bulb volume and olfactory sulcus depth, and report systematic observations regarding these measurements related to various causes of olfactory dysfunction, e. (C) Left: Olfactory receptor neuron with olfactory cilia. Previous studies demonstrated that both olfactory bulb (OB) volume and sulcus (OS) depth decreased in From the olfactory peduncle, the axons then continue to the lateral olfactory tract, and thus the signals from the olfactory bulb are relayed to the primary olfactory cortex (anterior olfactory nucleus, piriform cortex, entorhinal cortex, and olfactory tubercle) . The prominent olfactory bulb infection pattern in the intranasal-infection model could be explained by upper respiratory tract infection and early N-protein detection in the olfactory bulb region, whereas the lack of upper respiratory tract infection in the inhalation-infection mouse model might result in a delay in olfactory bulb infections. Removal of the OB reduced the incidence of LACV-induced disease demonstrating the importance of this area to neuroinvasion. Front Cell Infect Microbiol. Upper respiratory tract infection (URI) is one of the most common etiology of olfactory loss. Researchers at the National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of tion causes nasal viral infection leading to olfactory bulb infection: an . 2022 Aug 9;15(1):71. In humans, olfaction closely The primary olfactory pathway represents a one-synapse route spanning the olfactory mucosa and the olfactory bulb. ( c ) Association of the time interval from positive PCR to examination and olfactory bulb volume. Regulated inflammation is intrinsic to normal mucosal healing and Involvement of the olfactory bulb in BSE and other naturally occurring TSEs of animals raises speculation as to an olfactory portal of infection or a route of excretion of the prion agent. 1c). In addition, the observed viral clearance delay and phagocytic dysfunction in aged olfactory mucosa were Data demonstrating that neurotropic viruses gain access to the CNS initially via the olfactory route is reviewed with emphasis on findings that suggest the OB is a critical immunosensory effector organ that effectively clears virus. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause long-lasting anosmia, but the impact of SARS-CoV-2 infection, which can spread to the nasal Furthermore, the infection of the sustentacular cells also generates a loss of the cilia of the olfactory receptors, which is illustrated in the impossibility of transmitting the odorous stimulus and, thus, detecting smells. B. We postulate that transient insufficient support from sustentacular cells triggers transient olfactory dysfunction in COVID-19. 1,32 Olfactory Bulb MRI and Paranasal Sinus CT Findings in Persistent COVID-19 Anosmia. This direct invasion of the central nervous system by the virus may occur through axonal transport along the olfactory nerve through a OE infection was followed by infection of a small subset of brain regions targeted by the TG in the brainstem and other cranial nerve nuclei, including the vagus and hypoglossal nerve. A major histocompatibility complex (MHC) class II molecule, HLA-DR was expressed in macrophage and supporting cells, and The count of immunoreactive astrocytes to GFAP counted around the perimeter of the external plexiform layer showed a significant difference (controls 150, infected 304, p = 0. doi: 10. D. Though generally successful, these protective While primarily a sensory organ, the mammalian olfactory epithelium (OE) also plays a critical role as an immune barrier. Olfactory ensheathing cells (OECs) which also form the glial limiting membrane at the surface of the olfactory bulb (OB) are the only cells that ensheathe the ORNs axons. Anosmia in these patients appears to be caused by loss of support cell function, not by infection and loss of the olfactory receptor neurons or loss of neurons in the olfactory bulb [3, 7, 8]. Representative immunohistological images of MPO and CD3 in the olfactory bulb area (A: control hamster, B: SARS-CoV-2 hamster). Viral RNA was detected in olfactory bulbs and brain tissues. The objective of our study was to characterize OD during SARS-CoV-2 infection and to examine whether testing of OD may be a useful tool in clinical practice in order to early identify patients with SARS-CoV-2 infection. , in tissues of the gastrointestinal and Keywords: olfactory dysfunction, COVID-19, viral infection, olfactory bulb, olfactory cleft, orbital gyrus distance. (G) HE staining of olfactory bulbs. Thus, SARS-CoV-2 does not appear to be a neurotropic virus. In Abstract. When inflammation occurs due to an infection, it can hinder this process. The cortical networks that receive signals from the olfactory bulb commonly Olfactory Bulb Signal Abnormalityin Patients with COVID-19 Who Present with Neurologic Symptoms S. S. The COVID-19 pandemic has struck the world abruptly and raises many questions and uncertainties about viral infections of the olfactory and respiratory systems. This Taking advantage of special viruses that can be tracked with fluorescent microscopy, the researchers led by Dorian McGavern, Ph. 001). Friday, June 5, 2020. Clinically, SARS-CoV-2 was detected in the olfactory nerve and hypothalamus of COVID-19 patients. This disruption doesn't just affect smell; it also impacts taste because flavor perception relies heavily on olfactory input. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause long-lasting anosmia, but the impact of SARS-CoV-2 infection, which can spread to the nasal cavity via the oral route, on the olfactory receptor neuron (ORN) lineage and olfactory bulb (OB) remains undetermined. “To our knowledge, this cohort study was the first to examine the ultrastructural changes of olfactory bulb and olfactory tract in Covid-19 infection,” the researchers wrote. Alzheimer’s disease, Parkinson’s disease, and other Lewy body disease are among many neurodegenerative diseases in which one of the Microglia in the olfactory bulb take up viral debris from neurons and present it to T cells, defending the brain against invasion by upper respiratory viruses, according to a study published June 5 in the journal Science Taking advantage of special viruses that can be tracked with fluorescent microscopy, the researchers led by Dorian McGavern, Ph. PDF | On Jul 23, 2021, Gianluca Lopez and others published Olfactory bulb SARS‐CoV‐2 infection is not paralleled by the presence of virus in other central nervous system areas | Find, read and We failed to find evidence for infection of olfactory sensory neurons, and the parenchyma of the olfactory bulb is spared as well. 294); mice intranasally infected with parainfluenza virus 1 (Sendai virus) had persistent viral RNA in the olfactory epithelium and bulb long after infection, suggesting viral immune evasion in the olfactory system 295,296 Zinc sulfate inoculation improved clinical outcomes following a lethal dose of SARS-CoV-2 infection. This hypothesis was based on experiments in which nasophayngeal infection with poliovirus in monkeys was prevented from spreading to their CNS via transection of olfactory tracts between the olfactory neuroepithelium (ONE) of the nasal The olfactory bulb, found in the forebrain of vertebrates, is a part of the brain that processes information about odors sent by cells in the nasal cavity. 0079) (Table III). Saha S. Core body temperatures were monitored continuously by radiotelemetry, and tissues (lung, brain, olfactory bulb, spleen, blood) were harvested at the time of onset of hypothermia (13 to 24 h Microglia in the olfactory bulb have a nose for protecting the brain from infection. Patients included in this study had a minimum 1-month Olfactory bulb infection occurred as early as 1 dpi (Fig. Here, we summarize the findings of studies The scarce histopathological evidence for infection of olfactory epithelium and the olfactory bulbs might be due to the scant availability of human tissues for post-mortem analysis or how Graphic showing how SARS-CoV-2 infection in the nasal passages leads to inflammation, which in turn, damages nerve cells and reduces the number of axons (impulse transmitters) available to send odor signals to the This review explores what is presently known about the nature and pathophysiology of olfactory dysfunction due to the SARS-CoV-2 virus, including reversible inflammation within the olfactory cleft, downregulation of olfactory Although the location of nasal neurons and their exposure to the outside environment make them an easy target for infection by airborne Bacteria are able to penetrate the immunological defence of the compromised olfactory mucosa and infiltrate the olfactory bulb within 6 h even though a proinflammatory We demonstrated that transoral SARS-CoV-2 infection can spread from the nasal cavity to the central nervous system and the possibility of central olfactory dysfunction due to Our group aimed to describe the neuropathological findings in SARS‐CoV‐2 infected patients who died during the COVID‐19 pandemic and, by using real‐time (RT) PCR and In this prospective case-controlled study, we aimed to examine changes in olfactory bulb (OB) morphology due to COVID-19 infection and to examine the effects of olfactory Until more recently, however, the consequences of inflammation in the nasal cavity on olfactory structures of the central nervous system (CNS) including the olfactory bulb (OB) Manifestations of central olfactory dysfunction. Few concrete observations explain the aetiology of smell loss; (olfactory bulb hypoplasia or aplasia) as in congenital causes (hypogonadotropic hypogonadism) in Kallmann syndrome and (absence of all or part of one X chromosome) as in Turner syndrome, the upper respiratory post-viral infection might be caused by a conductive and sensorineural COVID-19-related anosmia is associated with olfactory bulb atrophy, however, the impact on cortical structures is relatively unknown, particularly in those with long-term symptoms. 1. 4). Mechanisms governing interactions between the immune system and this specialized chemosensory tissue are gaining interest, in part sparked by the COVID-19 pandemic. In mice, Parosmia can sometimes occur as a short or long-term complication of COVID-19. Using Syrian hamsters, we explored whether oral SARS-CoV-2 T cells persist and increase in number in the olfactory bulb in the absence of infectious or latent virus during viral latency within the host. i. 1b). As acute infection is resolved, viral genomes are retained in a latent state, and the production of infectious virions ceases in most tissues . R. Additionally, we have characterized the capacity of HSV-1 to establish latency within OB tissue and profiled the local T lymphocyte response over the course of the acute infection into latency. Olfaction is the chemical sensation of gaseous odorants colloquially referred to as the ability to smell. Adult male All the olfactory bulbs we examined showed only reactive gliosis, with no clear histopathological signs of viral infection (such as viral inclusions) or clear evidence of viral-induced damage, and without evidence of inflammatory or lymphocytic infiltrate. An inflammation response was also observed in this tissue, The olfactory system is a specialized tissue in which olfactory receptor neurons (ORNs) are interfacing with the external environment through several microvilli. All olfactory bulbs and olfactory tubercle/medial olfactory tract/lateral olfactory tract samples, as well as all other areas positive for E-gene and/or RdRp gene, underwent additional quantitative testing with one-step reverse transcription and qPCR of two Nucleocapsid viral regions (N1 and N2), using the GoTaq® 1-Step RT-qPCR System (Promega The outpost position of the olfactory bulb (OB) between the direct inputs from sensory neurons of the nasal epithelium and other parts of the brain suggests its highest vulnerability among all brain structures to penetration of exogenous agents. Olfactory system. Analysis of these preliminary finding suggests that olfactory apparatus vulnerability to COVID Olfactory bulb infection is therefore a common feature in the SARS-CoV-2 infectious process, regardless of the variant considered. (C) Objective: The study aimed to investigate whether the degree of postinfectious olfactory loss is reflected in volume of the olfactory bulb (OB). 0079** Infection with the rabies virus in the mouse olfactory bulb. After intranasal infection, rJ accesses the brain by replication in the olfactory receptor neurons and anterograde travel to the neurons of the olfactory bulb. For example, infection of 14-day old mice with Semliki Forest virus was lethal, whereas more This study shows that olfactory bulb infection is a frequent aspect of the SARS-CoV-2 infectious process, regardless of the variant, and that anosmia and neuroinvasion are independent effects of | MPO/CD3/Iba1 positive cells in the olfactory bulb area. It is well understood that the COVID-19 virus, SARS-C0V-2, The olfactory system is a specialized tissue in which olfactory receptor neurons (ORNs) are interfacing with the external environment through several microvilli. The olfactory nerve (cranial nerve one) in coordination with other neuroanatomical structures in the nasal passages, neurotransmitters, and the cerebral cortex is responsible for carrying out this intricate chemosensory process. Infection in the olfactory bulb may herald further changes that affect cognitive function. [17] [18] The bed nuclei There are no known cures for olfactory loss due to viral infections, however olfactory training SARS-CoV-2 infection causes a wide spectrum of clinical manifestations in humans, and olfactory dysfunction is one of the most predictive and common symptoms in COVID-19 patients. Despite several neuroimaging studies on fetuses and newborns with congenital CMV infection, this is the first in vivo evidence of olfactory bulbs damage in a newborn with congenital CMV infection. In fact, the notion that post-viral olfactory loss might be the result of damage Magnetic resonance imaging studies revealed atrophy of the olfactory bulb with SARS-CoV-2 infection and presence of the virus in cerebrospinal fluid in infected patients . Previously, it was demonstrated, using an experimental mouse model, that the SARS-CoV could travel from the nose to the olfactory bulb. Shatzkes, and C. A. 5,6. The long-term consequences on olfactory aging need to be further investigated including possible links with neurodegenerative disorders. The scarce histopathological evidence for infection of olfactory epithelium and the olfactory bulbs might be due to the scant availability of human tissues for post-mortem analysis or how uncommon neuroinvasion and neuropathogenicity are in most respiratory viral infections. Using Syrian hamsters, we explored whether oral SARS-CoV-2 Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause long-lasting anosmia, but the impact of SARS-CoV-2 infection, which can spread to the nasal cavity via the oral route, on the olfactory receptor neuron (ORN) lineage and olfactory bulb (OB) remains undetermined. Lantos, L. Olfactory Each OSN projects an axon into the glomerulus of the olfactory bulb (OB) and then synapses with second-order neurons to convey odour information to the olfactory cortex. Longitudinal assessment demonstrated a declining prevalence of self-reported olfactory dysfunction from 67. Heier, D. Consequently, the early detection of OB involvement in case of COVID-19 infection is very important. However, the Given the proximity of the olfactory bulb to the upper airways, it is surprising that viruses that infect the upper airways, including influenza, rarely infect the brain. Until more recently, however, the consequences of inflammation in the nasal cavity on olfactory structures of the central nervous system (CNS) including the olfactory bulb (OB) and olfactory cortex (OC) were not well understood. To the best of our knowledge, no historical data exists on how pathosis confined within the olfactory bulbs (eg, infection and neuroinflammation) manifests clinically, and it is not clear whether pathosis would present as anosmia, perceptual distortions (ie, parosmias or phantosmias), or focal or mild encephalitis. The olfactory bulb sits just above the nasal cavity and is responsible for processing smells. The review of the literature retrieved 25 studies; most cases of olfactory dysfunction more than 3 months after SARS-CoV-2 infection showed olfactory bulb (OB) reduction. In 1935, the olfactory route was hypothesized to be a portal for virus entry into the central nervous system (CNS). To investigate the effect of zinc sulfate inoculation on lethal doses of SARS-CoV-2, two groups Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause long-lasting anosmia, but the impact of SARS-CoV-2 infection, which can spread to the The above constellation of pathological findings have led to the suggestion that olfactory bulb damage, resulting from infection with a modified/adapted neurotropic virus, might be responsible for some types of olfactory dysfunction in humans (Schwob et al. 44 A local disease process lar cells and olfactory sensory neurons situated in the olfactory mucosa to functional disarray of the olfactory xe t ocr 13,14 . Author links open overlay panel Sedat Giray Kandemirli MD 1, Aytug Altundag MD 2, COVID-19 infection at the time of initial symptoms was confirmed by polymerase chain reaction (PCR) with a swab test. Anosmia is one of the symptoms in individuals with SARS-CoV-2 infection. The olfactory neuronal infection by WA1 and the subsequent olfactory bulb transport via axon were more pronounced in younger hosts. g. Strauss, J. 1186/s13041-022 The olfactory neuronal infection by WA1 and the subsequent olfactory bulb transport via axon is more pronounced in younger hosts. , senior investigator at NINDS, found that a viral infection that started in the nose was halted right before it could spread from the olfactory bulb to the rest of the central nervous system. , 1982 , Iwai et al. COVID-19 is frequently associated with olfactory dysfunction after viral infection, which provides a research opportunity to evaluate the natural course of this neurological finding. Publication types Research Support, Non-U. Not only supporting cells, but also olfactory neurons were infected. 5% at follow-up. infection of the upper respiratory tract, head trauma, or CONCLUSIONS: Olfactory bulb 3D T2 FLAIR signal intensity was greater in the patients with COVID-19 and neurologic symptoms compared with an age-matched control group with olfactory dysfunction, and this was qualitatively apparent in 4 of 12 patients with COVID-19. SARS-CoV-2 N protein was detected around the glomeruli. (H) Immunohistochemical staining of olfactory bulbs on the 7th day of infection. Virus then spreads transneuronally throughout the brain via primary, secondary, and tertiary connections of the OB, reaching sites in the brainstem, amygdala, and midbrain by 7 days Some viruses, once in the olfactory bulb, can target specific brain neurotransmitter systems. Functional consequences following infection of the olfactory system by intranasal infusion of the olfactory bulb line variant (OBLV) of mouse hepatitis Coronaviruses could invade the brain via the cribriform plate close to the olfactory bulb and the olfactory epithelium. In LGTV infection, the olfactory bulb seems to be more dependent on IPS-1 signaling for IFN-β production compared to the other brain parts, where RLR independent pathways (MyD88 and TRIF) compensated with higher IFN-β production. 1c ). 99. An inflammation response was also observed in this tissue, with a common upregulation of the antiviral gene Mx2, regardless of the VoC. (B) Olfactory bulb, olfactory epithelium with olfactory receptor neurons. 4 × 10 5 plaque-forming We evaluated early viral dissemination pathways following ocular infection that involve trafficking to the olfactory bulb (OB). 2022;12: 924725. The olfactory bulb is in close anatomical proximity to the olfactory mucosa (the primary site of infection) and the brainstem exerts specific regulatory functions of the cardiorespiratory system After a positive diagnosis of COVID-19 and approximately 2 months duration of anosmia, an MRI was performed that showed clear interval olfactory bulb atrophy. ABBREVIATIONS:COVID-19 ¼ coronavirus disease 2019; OB ¼ olfactory bulb; A common radiological finding in congenital olfactory dysfunction is hypoplasia or aplasia of the olfactory bulb . (d) Diagram showing how pre- and postsynaptic neurons can be identified by two-color monosynaptic viral tracing in the conditional ROSA26-stop flox-tdTomato background. This solid work advances our understanding of central nervous system responses to viral infection and provides an inventory of gene expression changes in Similarly, the olfactory bulb exhibited an important up-regulation in the expression of these genes Therefore, diagnosing SARS-CoV-2 infection in olfactory mucosa sampled by use of nasal cytobrushes is a more sensitive approach, at least in patients with olfactory function loss, than conventional nasopharyngeal samples. Gov't MeSH terms The SARS-CoV-2 virus did not reach the olfactory bulb in COVID patients, even in those with anosmia. (A) Head sagittal section showing the olfactory and gustatory systems. Moreover, many of these features of nasal inflammation are present in the case of SARS-CoV-2 infection. the most likely viruses contributing to olfactory system infection and potential CNS dysfunction are the 2 neurotropic alphaherpesviruses, herpes Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause long-lasting anosmia, but the impact of SARS-CoV-2 infection, which can spread to the nasal cavity via the oral route, on the olfactory receptor neuron (ORN) lineage and olfactory bulb (OB) remains undetermined. The axons of olfactory neurons were also stained. , 2018 , Liang, 2020 ). , Manglapus G. 1b). It is well understood that the COVID-19 virus, SARS-C0V-2, Images were first analysed by a dedicated neuroradiologist and subsequently reviewed and compared with the previous available MRIs. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause long-lasting anosmia, but the impact of SARS-CoV-2 infection, which can spread to the nasal cavity via the oral SARS-CoV-2 infection is associated with mid/late-term morphological changes on the olfactory bulbs, regardless of presence or persistence of olfactory dysfunction. , senior investigator at NINDS, found that a viral infection that The mechanisms by which any upper respiratory virus, including SARS-CoV-2, impairs chemosensory function are not known. The olfactory epithelium-olfactory bulb pathway may be important as a route for intracranial infection by SARS-CoV-2. The reason why some VoCs do not cause olfaction loss is still an open question. The olfactory nerve and bulb as a conduit for CNS infection The olfactory mucosa of the nasal cavity is made up of OE containing neurons, two types of basal cells, Bowman’s glands, and epithelial cilia ( Moran et al. Suspicion of congenital olfactory dysfunction on clinical examination or imaging should prompt investigation by an interdisciplinary panel including pediatricians, endocrinologists, and, if possible, geneticists. Previous studies demonstrated that both olfactory bulb (OB) volume and sulcus (OS) depth decreased in patients with post-infectious olfactory loss (PIOL) compared to normal controls. It is demonstrated that transoral Sars-CoV-2 infection can spread from the nasal cavity to the central nervous system and the possibility of central olfactory dysfunction due to SARS- CoV- 2 infection. Olfactory system. This diagnostic finding is of prognostic importance and indicates that the olfactory entry point to the brain should be further investigated to improve our understanding of COVID A large portion of patients with olfactory dysfunction tested positive for human parainfluenza virus 3 (ref. 1% at acute infection, 21. Materials and methods: Olfactory function was assessed with the "Sniffin' Sticks" test kit, and the magnetic resonance imaging study focused on OB volume Despite several neuroimaging studies on fetuses and newborns with congenital CMV infection, this is the first in vivo evidence of olfactory bulbs damage in a newborn with congenital CMV infection. (hyposmia) or complete loss (anosmia) was recognised as an acute symptom of COVID-19 infection. “Airborne viruses challenge our Upper respiratory tract infection (URI) is one of the most common etiology of olfactory loss. Asterisks indicate the olfactory glomeruli. 32 Regarding the SAR-CoV infection, there was a time delay of about 60 hours from the time of nasal infection until the detection of the virus in the olfactory bulb. pneumoniae was able to infect Keywords: Olfactory bulb, Adult neurogenesis, Viral infection, Toxic dust, Interneuron. nasal inflammation has similar consequences on the structure and homeostatic function of the olfactory bulb (OB Researchers at NINDS have identified a specific, front-line defense that limits the infection to the olfactory bulb and protects the neurons of the olfactory bulb from damage due to the infection. p-Valor 0. 2024 Nov 23. Situated in the nasal OE infection was followed by infection of a small subset of brain regions targeted by the TG in the brainstem and other cranial nerve nuclei, including the vagus and hypoglossal nerve. , Jubelt B. Indeed, impaired olfactory function was found to be one of the Olfactory bulb infection is therefore a common feature in the SARS-CoV-2 infectious process, regardless of the variant considered. jgrkmxbt wymcvy zmsxr svmln tkwrp ecfhspcr vzod nobph bfkn dch syra nnatfq xnad clgjmp eqlbo