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Carrot motley dwarf (CMD) is a viral disease complex caused by co-infection of the polerovirus carrot red leaf virus with the umbraviruses carrot mottle virus or carrot mottle mimic virus, and/or a tombusvirus like associated RNA (tlaRNA), which depend on co-infection with a helper polerovirus to gain aphid transmissibility. In 2020 and 2021 carrot samples from Washington, United States (U.S.), and parsley and cilantro samples from California, U.S., exhibiting typical symptoms of CMD were submitted for diagnosis. Initial RT-PCR diagnostic assays identified the typical CMD viruses in the carrot samples, however only the umbraviruses and tlaRNAs were detected in the parsley and cilantro samples; as such, these samples were retested with another RT-PCR assay for generic polerovirus detection. Unexpectedly, the poleroviruses Torilis crimson leaf virus (TorCLV) and fennel motley virus were identified. Subsequent RNA sequencing analysis was conducted to confirm these results and look for other emergent viruses. In addition to confirming the diagnostic results, the recently described polerovirus Foeniculum vulgare polerovirus, the umbraviruses Pastinaca umbravirus 1 and wild carrot mottle virus, and the tlaRNA Arracacha latent virus E associated RNA were identified, making this the first report of these viruses and tlaRNA in the U.S. Using phylogenetic and pairwise identity comparisons and RDP4 recombination analyses, we also identified a putative novel polerovirus, for which we propose the name parsley polerovirus, that appears to be a recombinant between carrot polerovirus 1, sharing 92% amino acid (aa) identity with the RNA dependent RNA polymerase in the 5' gene block, and TorCLV, sharing >98% aa identity with the capsid protein in the 3 gene block. This work adds to the growing list of polerovirus species exhibiting recombination between the 5' and 3' gene blocks, and highlights the unique, variable, and dynamic associations that can occur in polerovirus, umbravirus, and tlaRNA disease complexes.

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BACKGROUND: Bats are recognized as reservoir species for multiple viruses. However, little is known on bats' health and mortality. Thus, this study aimed to investigate the main causes of death of bats from Turin province (North-western Italy) and to describe gross and histopathological lesions potentially associated with the presence of selected bat viruses. RESULTS: A total of 71 bats belonging to 9 different species of the families Vespertilionidae and Molossidae were necropsied and samples of the main organs were submitted to histopathological examination. Also, aliquots of the small intestine, liver, spleen, lung, and brain were collected and submitted to biomolecular investigation for the identification of Coronaviridae, Poxviridae, Reoviridae (Mammalian orthoreovirus species), Rhabdoviridae (Vaprio ledantevirus and Lyssavirus species) and Kobuvirus. The majority of bats died from traumatic lesions due to unknown trauma or predation (n = 40/71, 56.3%), followed by emaciation (n = 13/71,18.3%). The main observed gross lesions were patagium and skin lesions (n = 23/71, 32.4%), forelimbs fractures (n = 15/71, 21.1%) and gastric distension (n = 10/71,14.1%). Histologically, the main lesions consisted of lymphoplasmacytic pneumonia (n = 24/71, 33.8%), skin/patagium dermatitis (n = 23/71, 32.4%), liver steatosis and hepatitis (n = 12, 16.9%), and white pulp depletion in the spleen (n = 7/71, 9.8%). Regarding emergent bat viruses, only poxvirus (n = 2, 2.8%) and orthoreovirus (n = 12/71, 16.9%) were detected in a low percentage of bats. CONCLUSIONS: Trauma is the main lesion observed in bats collected in Turin province (North-western Italy) associated with forelimb fractures and the detected viral positivity rate seems to suggest that they did not represent a threat for human health.

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We studied the effect of transmissibility and vaccination on the time required for an emerging strain of an existing virus to dominate in the infected population using a simulation-based experiment. The emergent strain is assumed to be completely resistant to the available vaccine. A stochastic version of a modified SIR model for emerging viral strains was developed to simulate surveillance data for infections. The proportion of emergent viral strain infections among the infected was modeled using a logistic curve and the time to dominance (TTD) was recorded for each simulation. A factorial experiment was implemented to compare the TTD values for different transmissibility coefficients, vaccination rates, and initial vaccination coverage. We discovered a non-linear relationship between TTD and the relative transmissibility of the emergent strain for populations with low vaccination coverage. Furthermore, higher vaccination coverage and high vaccination rates in the population yielded significantly lower TTD values. Vaccinating susceptible individuals against the current strain increases the susceptible pool of the emergent virus, which leads to the emergent strain spreading faster and requiring less time to dominate the infected population.

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The publications on animal coronavirus infections that have the greatest emerging potential, as well as official data from the World Organization for Animal Health (OIE) on cases of animal infection with COVID-19, are analyzed. Like most infectious diseases common to humans, coronavirus infections were first discovered in animals. Due to the increased rate of replication and recombination activity compared to other viruses, mutations occur more often in the genome of coronaviruses, which contribute to the acquisition of new qualities in order to consolidate in the host organism. Examples of cross-species transmission are not only SARS-CoV, MERS-CoV, and SARS-CoV-2, which are dangerous to humans, but also coronaviruses of agricultural and domestic animals, between which there is a genetic relationship. There are several known cases of zoo, wild, domestic, and farm animals displaying symptoms characteristic of COVID-19 and identification of the genome of the SARS-CoV-2 virus in them. The issue of cross-species transmission of coronavirus infections, in particular the reverse zoonosis of SARS-CoV-2 from animals to humans, is widely discussed. According to the conclusions of many researchers, including OIE experts, there is no direct evidence base for infection of humans with COVID-19 from animals. However, people with suspected COVID-19 and with a confirmed diagnosis are still advised to isolate not only from people but also from animals. A number of methods for specific prevention, diagnosis, and immunization against a wide range of coronavirus infections are being developed at the All-Russia Research Institute for Animal Protection.

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Application of high throughput sequencing (HTS) technologies enabled the first identification of Physostegia chlorotic mottle virus (PhCMoV) in 2018 in Austria. Subsequently, PhCMoV was detected in Germany and Serbia on tomatoes showing severe fruit mottling and ripening anomalies. We report here how prepublication data-sharing resulted in an international collaboration across eight laboratories in five countries, enabling an in-depth characterization of PhCMoV. The independent studies converged toward its recent identification in eight additional European countries and confirmed its presence in samples collected 20 years ago (2002). The natural plant host range was expanded from two to nine species across seven families, and we confirmed the association of PhCMoV presence with severe fruit symptoms on economically important crops such as tomato, eggplant, and cucumber. Mechanical inoculations of selected isolates in the greenhouse established the causality of the symptoms on a new indexing host range. In addition, phylogenetic analysis showed a low genomic variation across the 29 near-complete genome sequences available. Furthermore, a strong selection pressure within a specific ecosystem was suggested by nearly identical sequences recovered from different host plants through time. Overall, this study describes the European distribution of PhCMoV on multiple plant hosts, including economically important crops on which the virus can cause severe fruit symptoms. This work demonstrates how to efficiently improve knowledge on an emergent pathogen by sharing HTS data and provides a solid knowledge foundation for further studies on plant rhabdoviruses.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

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Ubiquitination of proteins is a post-translational modification process with many different cellular functions, including protein stability, immune signaling, antiviral functions and virus replication. While ubiquitination of viral proteins can be used by the host as a defense mechanism by destroying the incoming pathogen, viruses have adapted to take advantage of this cellular process. The ubiquitin system can be hijacked by viruses to enhance various steps of the replication cycle and increase pathogenesis. Emerging viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), flaviviruses like Zika and dengue, as well as highly pathogenic viruses like Ebola and Nipah, have the ability to directly use the ubiquitination process to enhance their viral-replication cycle, and evade immune responses. Some of these mechanisms are conserved among different virus families, especially early during virus entry, providing an opportunity to develop broad-spectrum antivirals. Here, we discuss the mechanisms used by emergent viruses to exploit the host ubiquitin system, with the main focus on the role of ubiquitin in enhancing virus replication.

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The global emergence of zoonotic viruses, including poxviruses, poses one of the greatest threats to human and animal health. Forty years after the eradication of smallpox, emerging zoonotic orthopoxviruses, such as monkeypox, cowpox, and vaccinia viruses continue to infect humans as well as wild and domestic animals. Currently, the geographical distribution of poxviruses in a broad range of hosts worldwide raises concerns regarding the possibility of outbreaks or viral dissemination to new geographical regions. Here, we review the global host ranges and current epidemiological understanding of zoonotic orthopoxviruses while focusing on orthopoxviruses with epidemic potential, including monkeypox, cowpox, and vaccinia viruses.

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Geminiviruses (family Geminiviridae) possess single-stranded circular DNA genomes that are replicated by cellular polymerases in plant host cell nuclei. In their hosts, geminivirus populations behave as ensembles of mutant and recombinant genomes, known as viral quasispecies. This favors the emergence of new geminiviruses with altered host range, facilitating new or more severe diseases or overcoming resistance traits. In warm and temperate areas several whitefly-transmitted geminiviruses of the genus Begomovirus cause the tomato yellow leaf curl disease (TYLCD) with significant economic consequences. TYLCD is frequently controlled in commercial tomatoes by using the dominant Ty-1 resistance gene. Over a 45 day period we have studied the diversification of three begomoviruses causing TYLCD: tomato yellow leaf curl virus (TYLCV), tomato yellow leaf curl Sardinia virus (TYLCSV) and tomato yellow leaf curl Malaga virus (TYLCMaV, a natural recombinant between TYLCV and TYLCSV). Viral quasispecies resulting from inoculation of geminivirus infectious clones were examined in plants of susceptible tomato (ty-1/ty-1), heterozygous resistant tomato (Ty-1/ty-1), common bean, and the wild reservoir Solanum nigrum. Differences in virus fitness across hosts were observed while viral consensus sequences remained invariant. However, the complexity and heterogeneity of the quasispecies were high, especially in common bean and the wild host. Interestingly, the presence or absence of the Ty-1 allele in tomato did not lead to differences in begomovirus mutant spectra. However, the fitness decrease of TYLCSV and TYLCV in tomato at 45 dpi might be related to an increase in CP (Coat protein) mutation frequency. In Solanum nigrum the recombinant TYLCMaV, which showed lower fitness than TYLCSV, at 45 dpi actively explored Rep (Replication associated protein) ORF but not the overlapping C4. Our results underline the importance of begomovirus mutant spectra during infections. This is especially relevant in the wild reservoir of the viruses, which has the potential to maintain highly diverse mutant spectra without modifying their consensus sequences.

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More than 200 viruses have been detected in bats. Some unique bat characteristics can explain the roles played in the maintenance and transmission of viruses: long phylogenetic history can have originated coevolution processes, great number of species are adapted to live in different environments, big mobility, long lifespan and gregarious behaviour of many species.To analyse zoonoses long longitudinal studies are needed with a multidisciplinary approximation to obtain the following eco-epidemiological data: colony size, number of bats per species, population structure, behaviour of each species, degree of contact between bats, social structure, remaining time of bats in the colony, colony type, foraging area, turnover rate of individuals, shelter temperature, relationship with other colonies and co-infection processes. These data allows assessing the epidemiological risk and which preventive measures are necessary to take.The structure and functionality of ecosystems are changing worldwide at an unprecedented rate and can modify the interactions between humans and infected bats. There are more or less local factors that can affect the emergence and spread of diseases (environmental alterations, changes in land use, human population growth, changes in human socioeconomic behavior or social structure, people mobility increase, trade increase, forest fires, extreme weather events, wars, breakdown in public health infrastructure, etc.).Twenty-three percent of all bat species in the world are decreasing. How does the regression of bat species affect the dynamic of viruses? The dichotomy between health risk and bat preservation is compatible with a preventive task based on more information and training.

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Mammalian retroviruses cause a variety of diseases in their hosts, including hematological and immunodeficiency disorders. Both human T-cell leukemia (HTLV) and human immunodeficiency (HIV) viruses originated from several independent zoonotic transmissions, indicating that cross-species transmissions from animal to humans may still occur. Thus, as the risk for retroviral transmissions from animals to humans increase, we investigated whether mammalian retroviruses are involved in selected pediatric idiopathic diseases whose symptoms evoke retroviral infections. Blood samples, sera, and synovial fluids, or bone marrow cells were collected from pediatric patients under 18 years of age with different autoimmune idiopathic diseases. Overall, we screened clinical samples from 110 children using sensitive nested and semi-nested PCR strategies targeting env genes, and a C-type retrovirus reverse transcriptase (RT) activity kit. All clinical samples were free of retroviral signatures, indicating the unlikelihood of an etiological role of the retroviruses we assessed in the pediatric diseases we tested.

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Emergent viruses have attracted attention during years 2003 and 2004. Ancient fears have reappeared regarding pathogenic agents, capable to result in epidemics with high mortality rates. Such events constitute really repeated threats. The analysis of mechanisms permitting emergence of these viruses has shown that they are not random phenomenons, but they result from accumulated factors leading to transmission from animals to men. Several modes of transmission of infection include: either direct transmission, or by intermediate vectors (mosquitoes, ticks and other (mammals) animals). Convergence of ecologic, economic and epidemiologic factors confer to the epidemics potential ability do spread widely. With the development of surveillance networks and improvement in diagnostic technologies, these "new" viruses are better identified. Recent occurrence of SARS and of the avian influenza are best examples of such experiences.