Relevance of animal infections in SARS-Cov-2 spread: an update after 1 year of pandemic.

In December 2019, several cases of pneumonia caused by a novel Coronavirus, later identified as SARS-CoV-2, were detected in the Chinese city of Wuhan. Due to its rapid, worldwide spread, on 11 March 2020 the World Health Organization declared a pandemic state. Since this new virus is genetically similar to the coronaviruses of bats, it was thought to have a zoonotic origin. Within a year of the appearance of SARS-CoV-2, several cases of infection were also reported in animals, suggesting animal-to-human and animal-to-animal transmission within mammals. Natural infection has been found in both companion and captive animals such as lions, tigers and gorillas. Among farm animals, the only ones found to be susceptible to SARS-CoV-2 infection so far are minks. Experimental infections have documented the susceptibility to SARS-CoV-2 of several animal species, such as humanized mice, hamsters, cats, dogs, ferrets, racoon dogs, cattle and non-human primates. Experimental infections are crucial for both elucidation of the role of animals in transmission and development of appropriate animal models for pathogenesis and therapy studies. This review aims to update the knowledge on natural and experimental SARS-CoV-2 infections in animals.

Between virus correlations in the outcome of infection across host species: evidence of virus genotype by host species interactions

Virus host shifts are a major source of outbreaks and emerging infectious diseases, and predicting the outcome of novel host and virus interactions remains a key challenge for virus research. The evolutionary relationships between host species can explain variation in transmission rates, virulence, and virus community composition between hosts, but the potential for different viruses to interact with host species effects has yet to be established. Here, we measure correlations in viral load of four Cripavirus isolates across experimental infections of 45 Drosophilidae host species. We find positive correlations between every pair of viruses tested, suggesting that broadly susceptible host clades could act as reservoirs and donors for certain types of viruses. Additionally, we find evidence of genotype-by-genotype interactions between viruses and host species, highlighting the importance of both host and virus traits in determining the outcome of virus host shifts. More closely related viruses tended to be more strongly correlated, providing tentative evidence that virus evolutionary relatedness may be a useful proxy for determining the likelihood of novel virus emergence, which warrants further research.Impact SummaryMany new infectious diseases are caused by viruses jumping into novel host species. Estimating the probability that jumps will occur, what the characteristics of new viruses will be, and how they are likely to evolve after jumping to new host species are major challenges. To solve these challenges, we require a detailed understanding of the interactions between different viruses and hosts, or metrics that can capture some of the variation in these interactions. Previous studies have shown that the evolutionary relationships between host species can be used to predict traits of infections in different hosts, including transmission rates and the damage caused by infection. However, the potential for different viruses to influence the patterns of these host species effects has yet to be determined. Here, we use four viruses of insects in experimental infections across 45 different fruit fly host species to begin to answer this question. We find similarities in the patterns of replication and persistence between all four viruses, suggesting susceptible groups of related hosts could act as reservoirs and donors for certain types of virus. However, we also find evidence that different virus genotypes interact in different ways with some host species. Viruses that were more closely related tended to behave in similar ways, and so we suggest that virus evolutionary relatedness may prove to be a useful metric for predicting the traits of novel infections and should be explored further in future studies.

Dynamics of experimental infection with Leptospira serogroup Pomona in different sheep breed

Most of the information about leptospirosis was obtained from experimental infections with rodents, which in spite of being relevant, do not provide all the answers about the disease in animals and human beings, given the variability of interactions which exist between the agent and the different hosts. Therefore, the objective of the present study was to verify the pathogenesis of the infection in native breeds of sheep of Brazil challenged with a strain of the serogroup Pomona. A total of 10 sheep were divided into two groups with five animals according to the breed. In each group four sheep were challenged by intraperitoneal route with a strain of the serogroup Pomona and one was used as control. Sheep were monitored for 60 days, with collection of blood for serologic diagnosis, as well as vaginal fluid and urine for microbiological and molecular analyses. After this period the animals were submitted to euthanasia and necropsy, with collection of tissues for microbiological, molecular and histopathologic diagnosis. All the challenged sheep presented anti-Leptospira antibodies. Crossbred sheep presented a lower concentration of titers and the antibodies were detected for a shorter period of time when compared to the Santa Inês sheep, with statistical difference in the concentration of the titers on the days 15 (p<0.05), 45 (p<0.05) and 60 (p<0.05) post-infection. There was no significant difference between the groups when comparing the positivity rates of the microscopic agglutination test (MAT) (p>0.05). Eight positive reactions in the urine and vaginal fluid PCR were detected in both groups, being four (50%) in urine and four (50%) in the vaginal fluid, however without statistical difference (p>0.05). In both groups there was a greater proportion of PCR positive samples in kidneys (71.4%) in relation to uterus (28.6%), however without significant difference (p>0.05). There was no significant difference between the groups when comparing the positivity rates of the PCR (p>0.05). The isolation of leptospires from the urine and kidney of a crossbred sheep was possible. Therefore, it is possible that the native sheep, especially the crossbred, may have a relation of resistance with strains of the serogroup Pomona. However the intensity and duration of this relation need to be elucidated and longer-lasting investigations of natural and experimental infections are necessary in order to determine the epidemiological nature of this relation.

K18-hACE2 Mice for Studies of COVID-19 Treatments and Pathogenesis Including Anosmia

ABSTRACTThe ongoing COVID-19 pandemic is associated with substantial morbidity and mortality. While much has been learned in the first months of the pandemic, many features of COVID-19 pathogenesis remain to be determined. For example, anosmia is a common presentation and many patients with this finding show no or only minor respiratory signs. Studies in animals experimentally infected with SARS-CoV-2, the cause of COVID-19, provide opportunities to study aspects of the disease not easily investigated in human patients. COVID-19 severity ranges from asymptomatic to lethal. Most experimental infections provide insights into mild disease. Here, using K18-hACE2 mice that we originally developed for SARS studies, we show that infection with SARS-CoV-2 causes severe disease in the lung, and in some mice, the brain. Evidence of thrombosis and vasculitis was detected in mice with severe pneumonia. Further, we show that infusion of convalescent plasma (CP) from a recovered COVID-19 patient provided protection against lethal disease. Mice developed anosmia at early times after infection. Notably, while treatment with CP prevented significant clinical disease, it did not prevent anosmia. Thus K18-hACE2 mice provide a useful model for studying the pathological underpinnings of both mild and lethal COVID-19 and for assessing therapeutic interventions.