scholarly journals Reduced Pathogenicity of the SARS-CoV-2 Omicron Variant in Hamsters

2022 ◽  
Author(s):  
Katherine McMahan ◽  
Victoria Giffin ◽  
Lisa Tostanoski ◽  
Benjamin Chung ◽  
Mazuba Siamatu ◽  
...  
Keyword(s):  
Weight Loss ◽  
Respiratory Tract ◽  
Lung Parenchyma ◽  
Clinical Disease ◽  
Upper Respiratory Tract ◽  
Viral Loads ◽  
Syrian Golden Hamsters ◽  
The World ◽  
Pulmonary Pathology ◽  
Upper Respiratory

The SARS-CoV-2 Omicron (B.1.1.529) variant has proven highly transmissible and has outcompeted the Delta variant in many regions of the world. Early reports have also suggested that Omicron may result in less severe clinical disease in humans. Here we show that Omicron is less pathogenic than prior SARS-CoV-2 variants in Syrian golden hamsters. Infection of hamsters with the SARS-CoV-2 WA1/2020, Alpha, Beta, or Delta strains led to 4-10% weight loss by day 4 and 10-17% weight loss by day 6, as expected. In contrast, infection of hamsters with two different Omicron challenge stocks did not result in any detectable weight loss, even at high challenge doses. Omicron infection still led to substantial viral replication in both the upper and lower respiratory tracts and pulmonary pathology, but with a trend towards higher viral loads in nasal turbinates and lower viral loads in lung parenchyma compared with WA1/2020 infection. These data suggest that the SARS-CoV-2 Omicron variant may result in more robust upper respiratory tract infection but less severe lower respiratory tract clinical disease compared with prior SARS-CoV-2 variants.

scholarly journals Asymptomatic COVID-19 Adult Outpatients identified as Significant Viable SARS-CoV-2 Shedders 

2021 ◽  
Author(s):  
Marie Glenet ◽  
Anne-Laure Lebreil ◽  
Laetitia Heng ◽  
Yohan N’Guyen ◽  
Ittah Meyer ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Control Measures ◽  
Upper Respiratory Tract ◽  
Rna Detection ◽  
Viral Loads ◽  
Infection Control Measures ◽  
Infected Adult ◽  
Asymptomatic Adult ◽  
Upper Respiratory ◽  
Kinetics Of

Abstract Differential kinetics of RNA loads and infectious viral levels in the upper respiratory tract between asymptomatic and symptomatic SARS-CoV-2 infected adult outpatients remain unclear limiting recommendations that may guide clinical management, infection control measures and occupational health decisions. In the present investigation, 496 (2.5%) of 17,911 French adult outpatients were positive for an upper respiratory tract SARS-CoV-2 RNA detection by a quantitative RT-PCR assay, of which 180 (36.3%) were COVID-19 asymptomatic. Of these adult asymptomatic viral shedders, 84.4% had mean to high RNA viral loads (Ct values<30) which median value was significantly higher than that observed in symptomatic subjects (P=0.029), and 50.6% were positive by cell culture assays of their upper respiratory tract specimens. Our findings indicate that COVID-19 asymptomatic adult outpatients are significant viable SARS-CoV-2 shedders in their upper respiratory tract playing a major potential role as SARS-CoV-2 transmitters in various epidemiological transmission chains, promoting COVID-19 resurgence in populations.

scholarly journals Studies on the pathogenesis of rinderpest in experimental cattle: IV. Proliferation of the virus following contact infection

1965 ◽  
Vol 63 (4) ◽  
pp. 497-506 ◽  
Author(s):  
W. P. Taylor ◽  
W. Plowright ◽  
R. Pillinger ◽  
C. S. Rampton ◽  
R. F. Staple
Keyword(s):  
Lymph Node ◽  
Respiratory Tract ◽  
Lymph Nodes ◽  
Natural Infection ◽  
Kidney Tissue ◽  
Lung Parenchyma ◽  
Published Data ◽  
Upper Respiratory Tract ◽  
Virus Content ◽  
Upper Respiratory

Cattle were infected with rinderpest virus by housing them for 24 hr. in stalls containing donor animals which had been reacting to the disease for 3–5 days. They were then transferred to individual clean stalls and killed on the 2nd to 10th days following first exposure. Various tissues were collected, particularly those of the upper and lower respiratory tracts, and their virus content was estimated in calf-kidney tissue cultures.Virus was recovered from 15 of 35 animals tested and in eight of these generalization had occurred, although only two had begun to show a pyrexial response. The stage of the infection could not be predicted from the time that had elapsed following exposure, since early, limited proliferation was encountered on the 3rd to the 10th days.It was considered that seven animals gave indications of the pathways by which natural infection had occurred. In each of these virus proliferation was established very early in the pharyngeal lymph node; in three the submaxillary lymph node was similarly involved and in four the palatal tonsil. It was suggested that these data probably indicated that infection always occurred via the upper respiratory tract.In three cases virus titres were highest in the bronchial or costocervical lymph nodes; this was construed as evidence for the additional involvement of the lower respiratory tract in primary infection.No infectivity could be demonstrated in the mucosae or lung parenchyma associated with the above-mentioned lymph nodes and this, together with previously published data, was accepted as strong presumptive evidence that the infecting virus passes through the mucosae without producing a local lesion or proliferating there. These results were compared briefly with those of Bedson & Duckworth (1963) for rabbit pox.

scholarly journals Induction of interferon response by high viral loads at early stage infection may protect against severe outcomes in COVID-19 patients

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eric C. Rouchka ◽  
Julia H. Chariker ◽  
Brian Alejandro ◽  
Robert S. Adcock ◽  
Richa Singhal ◽  
...  
Keyword(s):  
Gene Expression ◽  
Viral Load ◽  
Respiratory Tract ◽  
Disease Severity ◽  
Critical Factor ◽  
Interferon Response ◽  
Upper Respiratory Tract ◽  
Viral Loads ◽  
Antiviral Responses ◽  
Upper Respiratory

AbstractKey elements for viral pathogenesis include viral strains, viral load, co-infection, and host responses. Several studies analyzing these factors in the function of disease severity of have been published; however, no studies have shown how all of these factors interplay within a defined cohort. To address this important question, we sought to understand how these four key components interplay in a cohort of COVID-19 patients. We determined the viral loads and gene expression using high throughput sequencing and various virological methods. We found that viral loads in the upper respiratory tract in COVID-19 patients at an early phase of infection vary widely. While the majority of nasopharyngeal (NP) samples have a viral load lower than the limit of detection of infectious viruses, there are samples with an extraordinary amount of SARS-CoV-2 RNA and a high viral titer. No specific viral factors were identified that are associated with high viral loads. Host gene expression analysis showed that viral loads were strongly correlated with cellular antiviral responses. Interestingly, however, COVID-19 patients who experience mild symptoms have a higher viral load than those with severe complications, indicating that naso-pharyngeal viral load may not be a key factor of the clinical outcomes of COVID-19. The metagenomics analysis revealed that the microflora in the upper respiratory tract of COVID-19 patients with high viral loads were dominated by SARS-CoV-2, with a high degree of dysbiosis. Finally, we found a strong inverse correlation between upregulation of interferon responses and disease severity. Overall our study suggests that a high viral load in the upper respiratory tract may not be a critical factor for severe symptoms; rather, dampened antiviral responses may be a critical factor for a severe outcome from the infection.

scholarly journals A REVIEW ON AGENTS FOR THE TREATMENT OF LEPROSY INFECTION

2021 ◽  
pp. 25-29
Author(s):  
MUHANAD MOHAMED HABIBALLA AHMED ◽  
ANURADHA ◽  
PANKAJ WADHWA
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Respiratory Tract ◽  
Peripheral Nerves ◽  
Chronic Infection ◽  
Mycobacterium Leprae ◽  
Nontuberculous Mycobacterium ◽  
Upper Respiratory Tract ◽  
Multidrug Therapy ◽  
The World ◽  
Upper Respiratory

Leprosy is an ancient disease which is caused due to bacterial infection while curable but endures to be a substantial health problem in numerous parts across the world. It is an extremely contagious disease that is caused by any of 3 strains of bacteria such as Mycobacterium tuberculosis; Nontuberculous Mycobacterium; and Mycobacterium leprae. In several regions of Brazil, leprosy is a health issue which is still an endemic. Mainly skin, peripheral nerves, eyes, and mucosa of the upper respiratory tract are affected due to this chronic infection. As per the data shared by WHO across 159 countries globally, there were around 208,619 new leprosy cases reported. The global prevalence of leprosy is overcome with the aid of multidrug therapy which remains to be the chiefly targeted for treatment. The multidrug therapy gets attention as they show tremendous potential in fighting this disease. This review briefs about the different drugs and strategies which are used in treatment and superintendence of leprosy.

scholarly journals Intranasal ChAdOx1 nCoV-19/AZD1222 vaccination reduces viral shedding after SARS-CoV-2 D614G challenge in preclinical models

2021 ◽  
pp. eabh0755
Author(s):  
Neeltje van Doremalen ◽  
Jyothi N. Purushotham ◽  
Jonathan E. Schulz ◽  
Myndi G. Holbrook ◽  
Trenton Bushmaker ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Direct Contact ◽  
Infectious Virus ◽  
Rhesus Macaques ◽  
Upper Respiratory Tract ◽  
Preclinical Models ◽  
Viral Loads ◽  
Viral Shedding ◽  
Nasal Swabs ◽  
Upper Respiratory

ChAdOx1 nCoV-19/AZD1222 is an approved adenovirus-based vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) currently being deployed globally. Previous studies in rhesus macaques revealed that intramuscular vaccination with ChAdOx1 nCoV-19/AZD1222 provided protection against pneumonia but did not reduce shedding of SARS-CoV-2 from the upper respiratory tract. Here, we investigated whether intranasally administered ChAdOx1 nCoV-19 reduces detection of virus in nasal swabs after challenging vaccinated macaques and hamsters with SARS-CoV-2 carrying a D614G mutation in the spike protein. Viral loads in swabs obtained from intranasally vaccinated hamsters were decreased compared to control hamsters, and no viral RNA or infectious virus was found in lung tissue after a direct challenge or after direct contact with infected hamsters. Intranasal vaccination of rhesus macaques resulted in reduced virus concentrations in nasal swabs and a reduction in viral loads in bronchoalveolar lavage and lower respiratory tract tissue. Intranasal vaccination with ChAdOx1 nCoV-19/AZD1222 reduced virus concentrations in nasal swabs in two different SARS-CoV-2 animal models, warranting further investigation as a potential vaccination route for COVID-19 vaccines.

The World Health Organization's Revised Classification of Tumours of the Larynx, Hypopharynx, and Tracheax

1993 ◽  
Vol 102 (9) ◽  
pp. 666-669 ◽  
Author(s):  
Alfio Ferlito
Keyword(s):  
Respiratory Tract ◽  
Who Classification ◽  
Current Knowledge ◽  
World Health ◽  
Histological Classification ◽  
Upper Respiratory Tract ◽  
Histological Typing ◽  
The World ◽  
Upper Respiratory

A second edition of the Histological Typing of Upper Respiratory Tract Tumours in the WHO series International Histological Classification of Tumours was published in 1991. The new edition has been entitled Histological Typing of Tumours of the Upper Respiratory Tract and Ear. The task of revising the first edition, which was published in 1978, was undertaken at the WHO Center for Upper Respiratory Tract Tumours by K. Shanmugaratnam in collaboration with L. H. Sobin and pathologists in 8 countries. Several tumour types have been added to the classification, and some have been redefined in light of current knowledge. This presentation outlines the changes in the revised WHO classification as regards tumours of the larynx, hypopharynx, and trachea and discusses the grounds for said revisions.

scholarly journals Viral load in upper respiratory tract of COVID-19 patients detected by digital PCR

2020 ◽  
Author(s):  
Jiankang Zhao ◽  
Haibo Li ◽  
Hui Li ◽  
Qiaoling Wu ◽  
Ke Wu ◽  
...  
Keyword(s):  
Viral Load ◽  
Respiratory Tract ◽  
Digital Pcr ◽  
Upper Respiratory Tract ◽  
Rt Pcr ◽  
Lung Lesions ◽  
Viral Loads ◽  
Ct Value ◽  
Upper Respiratory ◽  
Close Contacts

Abstract Background: Upper respiratory tract specimens are widely applicable for the diagnosis of COVID-19. To date, no study has analyzed the actual viral loads in upper respiratory tract and its relationship with the severity of lung lesions, Ct value of RT-PCR and transmission capacity in COVID-19 patients.Methods: We retrospectively enrolled nine COVID-19 patients. Clinical data and close contacts of these patients were investigated. Respiratory samples were tested for SARS-CoV-2 with both normal RT-PCR and droplet digital PCR.Results: All the COVID-19 patients complicated with pneumonia. Viral loads in nasopharyngeal swabs were accurately quantified, and they had no direct correspondence with the severity of lung lesions. The Cycle Threshold (Ct) value of RT-PCR was approximately consistent with the absolute quantification of digital PCR. The spearman correlation coefficient between them was -0.952 with P value < 0.001. Close contacts of patients with very low viral load or no detected virus were not infected.Conclusions: Viral loads in nasopharyngeal swabs, could not predict the severity of lung lesions revealed by CT in COVID-19 patients. The infectious capacity of patients with low or absent viral load in upper respiratory tract was relatively weak, and wearing mask might be helpful for lower its spread.

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