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Virus Research May 2019HIV-1 spreads through both the release of cell-free particles and by cell-to-cell transmission. Mounting evidence indicates that cell-to-cell transmission is more... (Review)
Review
HIV-1 spreads through both the release of cell-free particles and by cell-to-cell transmission. Mounting evidence indicates that cell-to-cell transmission is more efficient than cell-free transmission of particles and likely influences the pathogenesis of HIV-1 infection. This mode of viral transmission also influences the generation and maintenance of the latent reservoir, which represents the main obstacle for curing the infection. In this review we will discuss general cell contact-dependent mechanisms that HIV-1 utilizes for its spread and the evidence pointing to cell-to-cell transmission as a mechanism for the establishment and maintenance of latent infection.
Topics: Animals; CD4-Positive T-Lymphocytes; Disease Reservoirs; HIV Infections; HIV-1; Humans; Mice; Virus Latency; Virus Physiological Phenomena
PubMed: 30905686
DOI: 10.1016/j.virusres.2019.03.014 -
Emerging Infectious Diseases Dec 2019Dogs are the main reservoir of Leishmania infantum and in some countries have been regularly culled as part of government policy to control visceral leishmaniasis. At...
Dogs are the main reservoir of Leishmania infantum and in some countries have been regularly culled as part of government policy to control visceral leishmaniasis. At the 13th Symposium of the Companion Vector-Borne Diseases World Forum in Windsor, UK, March 19-22, 2018, we consolidated a consensus statement regarding the usefulness of dog culling as a means of controlling visceral leishmaniasis. The statement highlighted the futility of culling infected dogs, whether healthy or sick, as a measure to control the domestic reservoir of L. infantum and reduce the risk for visceral leishmaniasis.
Topics: Animals; Disease Reservoirs; Dog Diseases; Dogs; Leishmaniasis; Leishmaniasis, Visceral
PubMed: 31742505
DOI: 10.3201/eid2512.190164 -
Viruses Jan 2019Bats are speculated to be reservoirs of several emerging viruses including coronaviruses (CoVs) that cause serious disease in humans and agricultural animals. These... (Review)
Review
Bats are speculated to be reservoirs of several emerging viruses including coronaviruses (CoVs) that cause serious disease in humans and agricultural animals. These include CoVs that cause severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), porcine epidemic diarrhea (PED) and severe acute diarrhea syndrome (SADS). Bats that are naturally infected or experimentally infected do not demonstrate clinical signs of disease. These observations have allowed researchers to speculate that bats are the likely reservoirs or ancestral hosts for several CoVs. In this review, we follow the CoV outbreaks that are speculated to have originated in bats. We review studies that have allowed researchers to identify unique adaptation in bats that may allow them to harbor CoVs without severe disease. We speculate about future studies that are critical to identify how bats can harbor multiple strains of CoVs and factors that enable these viruses to "jump" from bats to other mammals. We hope that this review will enable readers to identify gaps in knowledge that currently exist and initiate a dialogue amongst bat researchers to share resources to overcome present limitations.
Topics: Animals; Asymptomatic Diseases; Chiroptera; Coronavirus; Coronavirus Infections; Disease Outbreaks; Disease Reservoirs; Evolution, Molecular; Genome, Viral; Humans; Phylogeny; Severe acute respiratory syndrome-related coronavirus; Severe Acute Respiratory Syndrome; Swine
PubMed: 30634396
DOI: 10.3390/v11010041 -
Current Opinion in Virology Oct 2020Influenza D is the only type of influenza virus that mainly affects cattle with frequent spillover to other species. Since the initial description of influenza D virus... (Review)
Review
Influenza D is the only type of influenza virus that mainly affects cattle with frequent spillover to other species. Since the initial description of influenza D virus (IDV) in 2011, the virus has been found to circulate among cattle and swine populations worldwide. Research conducted during the past several years has led to an increased understanding of this novel influenza virus with bovines as a reservoir. In this review, we describe the current knowledge of epidemiology and host range of IDV followed by discussion of infection biology and animal model development for IDV. Finally, we review progress towards understanding of the pathogenesis and host response of IDV as well as developing preventive vaccines for IDV.
Topics: Animals; Antibodies, Viral; Cattle; Disease Models, Animal; Disease Reservoirs; Genome, Viral; Host Specificity; Host-Pathogen Interactions; Mice; Orthomyxoviridae Infections; Respiratory Tract Infections; Swine; Thogotovirus; Virus Replication
PubMed: 32932215
DOI: 10.1016/j.coviro.2020.08.004 -
Vaccine Feb 2020The environmental reservoir of Vibrio cholerae, the causative agent of cholera, has been a topic of scientific investigation ever since the discovery of the bacterium... (Review)
Review
The environmental reservoir of Vibrio cholerae, the causative agent of cholera, has been a topic of scientific investigation ever since the discovery of the bacterium itself. While the bacteria can be isolated from both clinical and environmental sources during epidemics, it evades isolation by conventional culture techniques during the period between successive epidemics. The problem is identifying the location and mode of survival and multiplication of V. cholerae during this inter-epidemic period. This information is crucial not only for epidemiological reasons, but also because the seasonality of cholera epidemics is plausibly mediated by the climate-regulated activity of the reservoir. This article focuses on the epidemiological importance of the environmental reservoir of V. cholerae, considering several investigations made on different types of aquatic fauna (zooplanktons, crustaceans, etc.) and flora (macrophytes and microphytes). After evaluating different lines of evidence, we make the case that certain species of cyanobacteria (Anabaena variabilis, Microcystis aeruginosa) can act as inter-epidemic reservoirs of V. cholerae. Physiological and functional aspects of this association are also discussed. We then present a hypothesis, expanding upon a previously published conceptual model, of how the climate-regulated seasonality of cholera epidemics is mediated by the effect of climatic factors on algal bloom and other local abiotic variables in the water, using Bangladesh as a model. Finally, another aspect of the climate-dependence of disease patterns is briefly explored: large-scale environmental signatures associated with cholera, and recent modelling efforts to predict cholera outbreaks based on coastal phytoplankton. The review, therefore, serves not only as a study of the identity of the inter-epidemic reservoir of V. cholerae, but also explores different ways in which the reservoir and the pathogen behaviour is affected by the climate, and the possible consequences it may have on disease pattern.
Topics: Bangladesh; Cholera; Climate; Disease Reservoirs; Epidemics; Eutrophication; Humans; Phytoplankton; Seasons; Vibrio cholerae
PubMed: 31285087
DOI: 10.1016/j.vaccine.2019.06.033 -
Journal of the American Veterinary... Feb 2009Leptospirosis has recently been classified as an emerging disease because of large clusters of cases resulting from exposure during recreational activities and natural... (Review)
Review
Leptospirosis has recently been classified as an emerging disease because of large clusters of cases resulting from exposure during recreational activities and natural disasters. In addition to their involvement in the prevention, diagnosis, and treatment of leptospirosis in animals, veterinarians serve an important role in public health by providing guidance and information on risk factors and prevention and control measures.
Topics: Animals; Anti-Bacterial Agents; Disease Outbreaks; Disease Reservoirs; Humans; Leptospira; Leptospirosis; Public Health; Zoonoses
PubMed: 19222355
DOI: 10.2460/javma.234.4.472 -
International Journal of Biological... 2020Mutation and adaptation have driven the co-evolution of coronaviruses (CoVs) and their hosts, including human beings, for thousands of years. Before 2003, two human CoVs... (Review)
Review
Mutation and adaptation have driven the co-evolution of coronaviruses (CoVs) and their hosts, including human beings, for thousands of years. Before 2003, two human CoVs (HCoVs) were known to cause mild illness, such as common cold. The outbreaks of severe acute respiratory syndrome (SARS) and the Middle East respiratory syndrome (MERS) have flipped the coin to reveal how devastating and life-threatening an HCoV infection could be. The emergence of SARS-CoV-2 in central China at the end of 2019 has thrusted CoVs into the spotlight again and surprised us with its high transmissibility but reduced pathogenicity compared to its sister SARS-CoV. HCoV infection is a zoonosis and understanding the zoonotic origins of HCoVs would serve us well. Most HCoVs originated from bats where they are non-pathogenic. The intermediate reservoir hosts of some HCoVs are also known. Identifying the animal hosts has direct implications in the prevention of human diseases. Investigating CoV-host interactions in animals might also derive important insight on CoV pathogenesis in humans. In this review, we present an overview of the existing knowledge about the seven HCoVs, with a focus on the history of their discovery as well as their zoonotic origins and interspecies transmission. Importantly, we compare and contrast the different HCoVs from a perspective of virus evolution and genome recombination. The current CoV disease 2019 (COVID-19) epidemic is discussed in this context. In addition, the requirements for successful host switches and the implications of virus evolution on disease severity are also highlighted.
Topics: Animals; Betacoronavirus; COVID-19; China; Chiroptera; Coronavirus; Coronavirus Infections; Disease Reservoirs; Evolution, Molecular; Host-Pathogen Interactions; Humans; Pandemics; Pneumonia, Viral; Rodentia; Severe acute respiratory syndrome-related coronavirus; SARS-CoV-2; Severe Acute Respiratory Syndrome; Zoonoses
PubMed: 32226286
DOI: 10.7150/ijbs.45472 -
Philosophical Transactions of the Royal... Sep 2019Dose is the nexus between exposure and all upstream processes that determine pathogen pressure, and is thereby an important element underlying disease dynamics.... (Review)
Review
Dose is the nexus between exposure and all upstream processes that determine pathogen pressure, and is thereby an important element underlying disease dynamics. Understanding the relationship between dose and disease is particularly important in the context of spillover, where nonlinearities in the dose-response could determine the likelihood of transmission. There is a need to explore dose-response models for directly transmitted and zoonotic pathogens, and how these interactions integrate within-host factors to consider, for example, heterogeneity in host susceptibility and dose-dependent antagonism. Here, we review the dose-response literature and discuss the unique role dose-response models have to play in understanding and predicting spillover events. We present a re-analysis of dose-response experiments for two important zoonotic pathogens (Middle East respiratory syndrome coronavirus and Nipah virus), to exemplify potential difficulties in differentiating between appropriate models with small exposure experiment datasets. We also discuss the data requirements needed for robust selection between dose-response models. We then suggest how these processes could be modelled to gain more realistic predictions of zoonotic transmission outcomes and highlight the exciting opportunities that could arise with increased collaboration between the virology and epidemiology disciplines. This article is part of the theme issue 'Dynamic and integrative approaches to understanding pathogen spillover'.
Topics: Animals; Animals, Wild; Coronavirus Infections; Disease Reservoirs; Environment; Henipavirus Infections; Host-Pathogen Interactions; Humans; Middle East Respiratory Syndrome Coronavirus; Nipah Virus
PubMed: 31401955
DOI: 10.1098/rstb.2019.0016 -
Emerging Microbes & Infections Sep 2017Central to the One Health approach and any disease eradication program is the question of whether a pathogen has a non-human reservoir. Despite well-established... (Review)
Review
Central to the One Health approach and any disease eradication program is the question of whether a pathogen has a non-human reservoir. Despite well-established conceptual frameworks that define a reservoir of infection, empirical characterization of reservoirs often remains controversial, challenging and sometimes misleading. What is essentially missing are applicable requirements that standardize the use of the term 'reservoir of infection' across multiple disciplines. We propose an empirical framework, considering maintenance and feasible transmission of a pathogen, to standardize the acceptance of a disease reservoir across multiple disciplines. We demonstrate the intended use of these requirements by applying them to different diseases that are known to infect both humans and animals.
Topics: Animals; Bacteria; Bacterial Infections; Communicable Disease Control; Disease Eradication; Disease Reservoirs; Disease Transmission, Infectious; Humans; One Health; Virus Diseases; Viruses
PubMed: 28874791
DOI: 10.1038/emi.2017.65 -
Veterinary Parasitology Feb 2018Leishmania infantum is a vector-borne zoonotic disease transmitted by phlebotomine sand flies and dogs are considered the main reservoir of the parasite. Feline... (Review)
Review
Leishmania infantum is a vector-borne zoonotic disease transmitted by phlebotomine sand flies and dogs are considered the main reservoir of the parasite. Feline leishmaniosis (FeL) caused by L. infantum is an emergent feline disease more and more frequently reported in endemic areas. This review summarizes current knowledge focusing similarities and differences with canine leishmaniosis (CanL). Cats are infected by the same Leishmania species than dogs but prevalence of the infection is lower and cases of disease are less frequently reported. Scarce information is available on adaptive immune response of cats naturally exposed to L. infantum infection and mechanisms responsible for susceptibility or resistance of feline hosts. However, about half of clinical cases of FeL are reported in cats with possible impaired immunocompetence. Coinfections or comorbidities are frequently detected in sick cats and they can contribute to a misrepresentation of clinical FeL albeit lesions associated with the presence of the parasite have been detected in skin, lymph nodes, spleen, bone marrow, liver, oral mucosa, stomach, large bowel, kidney, nasal exudate, lung, eye. As for dogs, skin or mucocutaneous lesions are the most common reason for veterinary consultation and finding on physical examination in cats with leishmaniosis. Molecular investigations of Leishmania DNA and anti- Leishmania antibody detection are largely used with the same methodologies for both CanL and FeL, however few information is available about their diagnostic performance in feline hosts. Treatment of cats with clinical FeL is still empirically based and off label by using the most common drugs prescribed to dogs. Life expectancy of cats with clinical FeL is usually good unless concurrent conditions or complications occur and prognosis does not seem significantly influenced by therapy or retroviral coinfection. According to current knowledge, cats can play a role as additional reservoir host of L. infantum and, in a « One Health » perspective, preventative measures should be taken. In conclusion, albeit feline infection and the associated cat disease caused by L. infantum is increasingly reported in endemic areas and have many similarities with CanL, consolidated evidence-based knowledge is not available and we cannot exclude that important differences between dogs and cats exist about transmission, immunopathogenesis and best practice for management and prevention.
Topics: Animals; Antibodies, Protozoan; Cat Diseases; Cats; Disease Reservoirs; Dog Diseases; Dogs; Leishmania infantum; Leishmaniasis, Visceral
PubMed: 29426470
DOI: 10.1016/j.vetpar.2018.01.012