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Trends in Immunology Dec 2020The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) marks the third highly pathogenic coronavirus to spill over into the human population.... (Review)
Review
The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) marks the third highly pathogenic coronavirus to spill over into the human population. SARS-CoV-2 is highly transmissible with a broad tissue tropism that is likely perpetuating the pandemic. However, important questions remain regarding its transmissibility and pathogenesis. In this review, we summarize current SARS-CoV-2 research, with an emphasis on transmission, tissue tropism, viral pathogenesis, and immune antagonism. We further present advances in animal models that are important for understanding the pathogenesis of SARS-CoV-2, vaccine development, and therapeutic testing. When necessary, comparisons are made from studies with SARS to provide further perspectives on coronavirus infectious disease 2019 (COVID-19), as well as draw inferences for future investigations.
Topics: Animals; COVID-19; Humans; SARS-CoV-2
PubMed: 33132005
DOI: 10.1016/j.it.2020.10.004 -
Nature Reviews. Microbiology Aug 2021Human respiratory virus infections lead to a spectrum of respiratory symptoms and disease severity, contributing to substantial morbidity, mortality and economic losses... (Review)
Review
Human respiratory virus infections lead to a spectrum of respiratory symptoms and disease severity, contributing to substantial morbidity, mortality and economic losses worldwide, as seen in the COVID-19 pandemic. Belonging to diverse families, respiratory viruses differ in how easy they spread (transmissibility) and the mechanism (modes) of transmission. Transmissibility as estimated by the basic reproduction number (R) or secondary attack rate is heterogeneous for the same virus. Respiratory viruses can be transmitted via four major modes of transmission: direct (physical) contact, indirect contact (fomite), (large) droplets and (fine) aerosols. We know little about the relative contribution of each mode to the transmission of a particular virus in different settings, and how its variation affects transmissibility and transmission dynamics. Discussion on the particle size threshold between droplets and aerosols and the importance of aerosol transmission for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza virus is ongoing. Mechanistic evidence supports the efficacies of non-pharmaceutical interventions with regard to virus reduction; however, more data are needed on their effectiveness in reducing transmission. Understanding the relative contribution of different modes to transmission is crucial to inform the effectiveness of non-pharmaceutical interventions in the population. Intervening against multiple modes of transmission should be more effective than acting on a single mode.
Topics: Aerosols; COVID-19; Humans; Hygiene; Personal Protective Equipment; SARS-CoV-2
PubMed: 33753932
DOI: 10.1038/s41579-021-00535-6 -
Acta Medica Portuguesa Dec 2019Over the last few decades, behavioral changes in sexual practices have made oral transmission of traditional sexually transmissible infections increasingly recognized.... (Review)
Review
Over the last few decades, behavioral changes in sexual practices have made oral transmission of traditional sexually transmissible infections increasingly recognized. Patients harboring a sexually transmissible infection may first present lesions on the oral cavity, as these may be visible and interfere with basic functions such as speech or swallowing. Moreover, the oral cavity may function as a reservoir for future spread of these infections. In order to successfully control this problem, a greater focus on oral sex should be persued, along with promotion of the use of condom and education on safe oral sex practices. Furthermore, examination of the oral cavity should is essential when evaluating any patient suspected of harboring a sexually transmissible infection. In this article, oral transmission of several viral and bacterial infections is reviewed, including human papillomavirus infection, genital herpes, syphilis and gonorrhea, among others.
Topics: Chlamydia Infections; Chlamydia trachomatis; Gonorrhea; HIV Infections; Herpes Simplex; Humans; Mouth Diseases; Papillomavirus Infections; Safe Sex; Sexual Behavior; Sexually Transmitted Diseases; Syphilis
PubMed: 31851887
DOI: 10.20344/amp.12191 -
Postgraduate Medical Journal Sep 1978The laboratory transmission to animals of an apparently degenerative disease of the nervous system, Creutzfeldt-Jakob disease (CJD), is now well established. Important... (Review)
Review
The laboratory transmission to animals of an apparently degenerative disease of the nervous system, Creutzfeldt-Jakob disease (CJD), is now well established. Important questions arising from this observation are the possibility of natural transmission or infectivity and the existence of other similarly transmissible diseases. Epidemiological studies have revealed some possible clusters of CJD and also an association with previous craniotomy, but there is no definite evidence of natural infection. A few instances have been reported of experimental CJD in animals following inoculation with material from Alzheimer's disease, but apart from this there is so far no evidence of transmission of any other form of degenerative nervous disease.
Topics: Animals; Creutzfeldt-Jakob Syndrome; Cricetinae; Guinea Pigs; Haplorhini; Humans; Pan troglodytes; Slow Virus Diseases; Time Factors
PubMed: 103082
DOI: 10.1136/pgmj.54.635.591 -
Food Safety (Tokyo, Japan) Dec 2016Many mammalian species can be affected by prion diseases, also known as transmissible spongiform encephalopathies (TSEs). "Classical" bovine spongiform encephalopathy... (Review)
Review
Many mammalian species can be affected by prion diseases, also known as transmissible spongiform encephalopathies (TSEs). "Classical" bovine spongiform encephalopathy (C-BSE) was the first prion disease recognized in cattle and it is the only known zoonotic prion disease, having caused variant Creutzfeldt-Jakob disease (vCJD) in humans. Based on the biochemical signatures of disease-associated prion protein (PrP), two distinct forms of atypical bovine spongiform encephalopathies (H-BSE and L-BSE) have been distinguished from C-BSE since 2004. To date there is no comprehensive information about the origin of atypical BSEs (sporadic vs. acquired) and this has an influence on the interpretation of the knowledge gathered from experimental studies, regarding how well such models may represent the real distribution of the agent in the body of naturally affected animals. Moreover, there are only very limited data available concerning the pathogenesis of both atypical BSE forms, as compared to C-BSE. Thus, precautions that are presently taken to minimize the risk of prion contamination of the food supply might not be as effective at preventing the spread of these recently recognized strains. In the last few years a wide range of experimental transmission studies of atypical strains in different animal hosts have been performed. The most recent data on classical and atypical BSE studies concerning characteristics, pathogenesis and transmissions in cattle will be summarized in this review.
PubMed: 32231917
DOI: 10.14252/foodsafetyfscj.2016018 -
Proceedings of the National Academy of... Aug 2022Previous studies have shown that the Eurasian avian-like H1N1 (EA H1N1) swine influenza viruses circulated widely in pigs around the world and formed multiple genotypes...
Previous studies have shown that the Eurasian avian-like H1N1 (EA H1N1) swine influenza viruses circulated widely in pigs around the world and formed multiple genotypes by acquiring non-hemagglutinin and neuraminidase segments derived from other swine influenza viruses. Swine influenza control is not a priority for the pig industry in many countries, and it is worrisome that some strains may become more pathogenic and/or transmissible during their circulation in nature. Our routine surveillance indicated that the EA H1N1 viruses obtained different internal genes from different swine influenza viruses and formed various new genotypes. In this study, we found that a naturally isolated swine influenza reassortant, A/swine/Liaoning/265/2017 (LN265), a representative strain of one of the predominant genotypes in recent years, is lethal in mice and transmissible in ferrets. LN265 contains the hemagglutinin, neuraminidase, and matrix of the EA H1N1 virus; the basic polymerase 2, basic polymerase 1, acidic polymerase (PA), and nucleoprotein of the 2009 H1N1 pandemic virus; and the nonstructural protein of the North American triple-reassortment H1N2 virus. By generating and testing a series of reassortants and mutants, we found that four gradually accumulated mutations in PA are responsible for the increased pathogenicity and transmissibility of LN265. We further revealed that these mutations increase the messenger RNA transcription of viral proteins by enhancing the endonuclease cleavage activity and viral RNA-binding ability of the PA protein. Our study demonstrates that EA H1N1 swine influenza virus became pathogenic and transmissible in ferrets by acquiring key mutations in PA and provides important insights for monitoring field strains with pandemic potential.
Topics: Animals; Ferrets; Genotype; Influenza A Virus, H1N1 Subtype; Mice; Mutation; Neuraminidase; Orthomyxoviridae Infections; Phylogeny; RNA-Dependent RNA Polymerase; Reassortant Viruses; Swine; Swine Diseases; Viral Proteins
PubMed: 35969783
DOI: 10.1073/pnas.2203919119 -
Current Opinion in Virology Oct 2021SARS-CoV-2 emerged in China as a zoonotic virus in December 2019. The virus proved to be human-to-human transmissible and its global spread resulted in the ongoing... (Review)
Review
SARS-CoV-2 emerged in China as a zoonotic virus in December 2019. The virus proved to be human-to-human transmissible and its global spread resulted in the ongoing COVID-19 pandemic, associated with high morbidity and mortality. Vaccines were developed at an unprecedented speed and proved to be efficacious in preventing disease, but it remains to be determined if vaccines are able to interrupt transmission. Moreover, virus variants of concern continue to emerge that appear more transmissible and/or less sensitive to virus-specific immune responses. Here, we briefly review the role of animal models in assessing prophylactic and therapeutic options to interrupt SARS-CoV-2 transmission.
Topics: Animals; COVID-19; Cricetinae; Disease Models, Animal; Humans; SARS-CoV-2
PubMed: 34256352
DOI: 10.1016/j.coviro.2021.06.007 -
Current Opinion in Virology Aug 2023To cause pandemics, zoonotic respiratory viruses need to adapt to replication in and spread between humans, either via (indirect or direct) contact or through the air... (Review)
Review
To cause pandemics, zoonotic respiratory viruses need to adapt to replication in and spread between humans, either via (indirect or direct) contact or through the air via droplets and aerosols. To render influenza A viruses transmissible via air, three phenotypic viral properties must change, of which receptor-binding specificity and polymerase activity have been well studied. However, the third adaptive property, hemagglutinin (HA) acid stability, is less understood. Recent studies show that there may be a correlation between HA acid stability and virus survival in the air, suggesting that a premature conformational change of HA, triggered by low pH in the airways or droplets, may render viruses noninfectious before they can reach a new host. We here summarize available data from (animal) studies on the impact of HA acid stability on airborne transmission and hypothesize that the transmissibility of other respiratory viruses may also be impacted by an acidic environment in the airways.
Topics: Humans; Animals; Influenza A virus; Hemagglutinins; Hemagglutinin Glycoproteins, Influenza Virus; Respiratory System; Adaptation, Physiological; Influenza, Human; Orthomyxoviridae Infections
PubMed: 37307646
DOI: 10.1016/j.coviro.2023.101335 -
Journal of Virology Jun 2023Although influenza A viruses of several subtypes have occasionally infected humans, to date only those of the H1, H2, and H3 subtypes have led to pandemics and become...
Although influenza A viruses of several subtypes have occasionally infected humans, to date only those of the H1, H2, and H3 subtypes have led to pandemics and become established in humans. The detection of two human infections by avian H3N8 viruses in April and May of 2022 raised pandemic concerns. Recent studies have shown the H3N8 viruses were introduced into humans from poultry, although their genesis, prevalence, and transmissibility in mammals have not been fully elucidated. Findings generated from our systematic influenza surveillance showed that this H3N8 influenza virus was first detected in chickens in July 2021 and then disseminated and became established in chickens over wider regions of China. Phylogenetic analyses revealed that the H3 HA and N8 NA were derived from avian viruses prevalent in domestic ducks in the Guangxi-Guangdong region, while all internal genes were from enzootic poultry H9N2 viruses. The novel H3N8 viruses form independent lineages in the glycoprotein gene trees, but their internal genes are mixed with those of H9N2 viruses, indicating continuous gene exchange among these viruses. Experimental infection of ferrets with three chicken H3N8 viruses showed transmission through direct contact and inefficient transmission by airborne exposure. Examination of contemporary human sera detected only very limited antibody cross-reaction to these viruses. The continuing evolution of these viruses in poultry could pose an ongoing pandemic threat. A novel H3N8 virus with demonstrated zoonotic potential has emerged and disseminated in chickens in China. It was generated by reassortment between avian H3 and N8 virus(es) and long-term enzootic H9N2 viruses present in southern China. This H3N8 virus has maintained independent H3 and N8 gene lineages but continues to exchange internal genes with other H9N2 viruses to form novel variants. Our experimental studies showed that these H3N8 viruses were transmissible in ferrets, and serological data suggest that the human population lacks effective immunological protection against it. With its wide geographical distribution and continuing evolution in chickens, other spillovers to humans can be expected and might lead to more efficient transmission in humans.
Topics: Animals; Humans; Influenza, Human; Chickens; Influenza A Virus, H3N8 Subtype; Influenza in Birds; Public Health; Influenza A Virus, H9N2 Subtype; Phylogeny; Ferrets; China; Poultry
PubMed: 37289052
DOI: 10.1128/jvi.00434-23 -
Emerging Microbes & Infections Dec 2023The fitness of multidrug-resistant tuberculosis (MDR-TB) is thought to be an important determinant of a strain's ability to be transmitted. Studies in the laboratory...
The fitness of multidrug-resistant tuberculosis (MDR-TB) is thought to be an important determinant of a strain's ability to be transmitted. Studies in the laboratory have demonstrated that MDR-TB strains have reduced fitness but the relative transmissibility of MDR-TB versus drug-susceptible (DS) TB strains in human populations remains unresolved. We used data on genomic clustering from our previous molecular epidemiological study in Songjiang (2011-2020) and Wusheng (2009-2020), China, to compare the relative transmissibility of MDR-TB versus DS-TB. Genomic clusters were defined with a threshold distance of 12-single-nucleotide-polymorphisms and the risk for MDR-TB clustering was analyzed by logistic regression. In total, 2212 culture-positive pulmonary TB patients were enrolled in Songjiang and 1289 in Wusheng. The clustering rates of MDR-TB and DS-TB strains were 19.4% (20/103) and 26.3% (509/1936), respectively in Songjiang, and 43.9% (29/66) and 26.0% (293/1128) in Wusheng. The risk of MDR-TB clustering was 2.34 (95% CI 1.38-3.94) times higher than DS-TB clustering in Wusheng and 0.64 (95% CI 0.38-1.06) times lower in Songjiang. Neither lineage 2, compensatory mutations nor rpoB S450L were significantly associated with MDR-TB transmission, and katG S315 T increased MDR-TB transmission only in Wusheng (OR 5.28, 95% CI 1.42-19.21). MDR-TB was not more transmissible than DS-TB in either Songjiang or Wusheng. It appears that the different transmissibility of MDR-TB in Songjiang and Wusheng is likely due to differences in the quality of the local TB control programmes. Suggesting that the most effective way to control MDR-TB is by improving local TB control programmes.
Topics: Humans; Mycobacterium tuberculosis; Antitubercular Agents; Tuberculosis, Multidrug-Resistant; Tuberculosis, Pulmonary; Mutation; China; Drug Resistance, Multiple, Bacterial; Microbial Sensitivity Tests
PubMed: 36924242
DOI: 10.1080/22221751.2023.2192301