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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 -
Microbiology Spectrum Jul 2017Transmissibility is the defining characteristic of infectious diseases. Quantifying transmission matters for understanding infectious disease epidemiology and designing... (Review)
Review
Transmissibility is the defining characteristic of infectious diseases. Quantifying transmission matters for understanding infectious disease epidemiology and designing evidence-based disease control programs. Tracing individual transmission events can be achieved by epidemiological investigation coupled with pathogen typing or genome sequencing. Individual infectiousness can be estimated by measuring pathogen loads, but few studies have directly estimated the ability of infected hosts to transmit to uninfected hosts. Individuals' opportunities to transmit infection are dependent on behavioral and other risk factors relevant given the transmission route of the pathogen concerned. Transmission at the population level can be quantified through knowledge of risk factors in the population or phylogeographic analysis of pathogen sequence data. Mathematical model-based approaches require estimation of the per capita transmission rate and basic reproduction number, obtained by fitting models to case data and/or analysis of pathogen sequence data. Heterogeneities in infectiousness, contact behavior, and susceptibility can have substantial effects on the epidemiology of an infectious disease, so estimates of only mean values may be insufficient. For some pathogens, super-shedders (infected individuals who are highly infectious) and super-spreaders (individuals with more opportunities to transmit infection) may be important. Future work on quantifying transmission should involve integrated analyses of multiple data sources.
Topics: Bacteria; Bacterial Infections; Communicable Diseases; Epidemiologic Methods; Models, Theoretical; Virus Diseases
PubMed: 28812540
DOI: 10.1128/microbiolspec.MTBP-0005-2016 -
Microbiology Spectrum Jun 2016A vast number of novel tick-related microorganisms and tick-borne disease agents have been identified in the past 20 years, and more are being described due to several... (Review)
Review
A vast number of novel tick-related microorganisms and tick-borne disease agents have been identified in the past 20 years, and more are being described due to several factors, from the curiosity of clinicians faced with unusual clinical syndromes to new tools used by microbiologists and entomologists. Borrelioses, ehrlichioses, anaplasmosis, and tick-borne rickettsial diseases are some of the emerging diseases that have been described throughout the world in recent years. In this article, we focus on the bacterial agents and diseases that have been recognized in the past 3 years and refer to major recent reviews of other recognized infections.
Topics: Animals; Argasidae; Borrelia; Ehrlichia; Ehrlichiosis; Humans; Ixodidae; Lyme Disease; Rickettsia; Rickettsia Infections; Tick-Borne Diseases
PubMed: 27337487
DOI: 10.1128/microbiolspec.EI10-0012-2016 -
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 -
Travel Medicine and Infectious Disease 2020It has been well documented that Zika virus (ZIKV) can be sexually transmitted. Dengue virus (DENV) shows many similarities with ZIKV; both belong to the genus... (Review)
Review
It has been well documented that Zika virus (ZIKV) can be sexually transmitted. Dengue virus (DENV) shows many similarities with ZIKV; both belong to the genus Flavivirus and share the same main vector route of transmission. Moreover, they share overall architectural features on a molecular level, with a highly similar structure and distinctive insertions, deletions and mutations of their respective E proteins, and it has been suggested that they use a common pathophysiological pathway. In view of similarities with other sexually transmissible viruses, the question arises as to whether DENV could also be sexually transmissible. Limited animal model data do not suggest otherwise. The presence of dengue virus in - and human-to-human, non-vector transmission from - various bodily fluids other than semen or vaginal secretions has been documented anecdotally. Several anecdotal reports described prolonged presence of DENV in semen, urine and vaginal secretions. In 2019, two cases of likely sexual transmission were reported from Spain and South Korea, respectively. We discuss the evidence for and against a relevant DENV sexual transmission potential, highlight controversies and propose a future research agenda on this issue.
Topics: Animals; Body Fluids; Dengue; Dengue Virus; Female; Humans; Male; Mosquito Vectors; Sexual Behavior; Sexually Transmitted Diseases
PubMed: 32473313
DOI: 10.1016/j.tmaid.2020.101753 -
European Review For Medical and... Jul 2020In late December 2019 in Wuhan (China), Health Commission reported a cluster of pneumonia cases of unknown etiology, subsequently isolated and named Severe Acute... (Review)
Review
OBJECTIVE
In late December 2019 in Wuhan (China), Health Commission reported a cluster of pneumonia cases of unknown etiology, subsequently isolated and named Severe Acute Respiratory Syndrome (SARS) Coronavirus 2 (CoV-2). In this review, the main transmission routes and causes of mortality associated with COVID-19 were investigated.
MATERIAL AND METHODS
A review was carried out to recognize relevant research available until 10 April 2020.
RESULTS
The main transmission routes of COVID-19 have been the following: animal to human and human-to-human pathways, namely: respiratory transmission; oro-fecal transmission; air, surface-human transmission. Transmission from asymptomatic persons, healthcare transmission, and interfamily transmission have been well documented.
CONCLUSIONS
SARS-CoV-2 possesses powerful pathogenicity and transmissibility. It is presumed to spread primarily via respiratory droplets and close contact. The most probable transmission pathway is definitely the inter-human one. Asymptomatic patients seem to play a crucial role in spreading the infection. Because of COVID-19 infection pandemic potential, careful surveillance is essential to monitor its future host adaptation, viral evolution, infectivity, transmissibility, and pathogenicity in order to gain an effective vaccine and flock immunity and reduce mortality as soon and as much as it is possible.
Topics: Animals; Asymptomatic Diseases; Betacoronavirus; COVID-19; Coronavirus Infections; Feces; Humans; Infectious Disease Transmission, Vertical; Pandemics; Pneumonia, Viral; SARS-CoV-2; Sputum
PubMed: 32744718
DOI: 10.26355/eurrev_202007_22296 -
Journal of Zhejiang University.... May 2020Since its emergence in December 2019, corona virus disease 2019 (COVID-19) has impacted several countries, affecting more than 90 thousand patients and making it a... (Review)
Review
Since its emergence in December 2019, corona virus disease 2019 (COVID-19) has impacted several countries, affecting more than 90 thousand patients and making it a global public threat. The routes of transmission are direct contact, and droplet and possible aerosol transmissions. Due to the unique nature of dentistry, most dental procedures generate significant amounts of droplets and aerosols, posing potential risks of infection transmission. Understanding the significance of aerosol transmission and its implications in dentistry can facilitate the identification and correction of negligence in daily dental practice. In addition to the standard precautions, some special precautions that should be implemented during an outbreak have been raised in this review.
Topics: Aerosols; Betacoronavirus; COVID-19; Coronavirus Infections; Cross Infection; Dentistry; Hand Hygiene; Humans; Infection Control; Pandemics; Personal Protective Equipment; Pneumonia, Viral; SARS-CoV-2
PubMed: 32425001
DOI: 10.1631/jzus.B2010010