Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has caused the coronavirus disease 2019 (COVID‐19) pandemic in humans since late 2019. Here, we investigated SARS‐CoV‐2 infection in dogs and cats during COVID‐19 quarantine at private veterinary hospitals in Thailand. From April to May 2021, we detected SARS‐CoV‐2 in three out of 35 dogs and one out of nine cats from four out of 17 households with confirmed COVID‐19 patients. SARS‐CoV‐2 RNA was detected from one of the nasal, oral, rectal and environmental swabs of dog‐A (15 years old, mixed breed, male dog), cat‐B (1 year old, domestic shorthair, male cat), dog‐C (2 years old, mixed breed, female dog) and dog‐D (4 years old, Pomeranian, female dog). The animals tested positive for SARS‐CoV‐2 RNA from 4 to 30 days after pet owners were confirmed to be COVID‐19 positive. The animals consecutively tested positive for SARS‐CoV‐2 RNA for 4 to 10 days. One dog (dog‐A) showed mild clinical signs, while the other dogs and a cat remained asymptomatic during quarantine at the hospitals. SARS‐CoV‐2 specific neutralizing antibodies were detected in both the dogs and cat by surrogate virus neutralization tests. Phylogenetic and genomic mutation analyses of whole genome sequences of three SARS‐CoV‐2 strains from the dogs and cat revealed SARS‐CoV‐2 of the Alpha variant (B.1.1.7 lineage). Our findings are suggestive of human‐to‐animal transmission of SARS‐CoV‐2 in COVID‐19‐positive households and contamination of viral RNA in the environment. Public awareness of SARS‐CoV‐2 infection in pet dogs and cats in close contact with COVID‐19 patients should be raised.

From wild dogs (Lycaon pictus) in the Serengeti to tigers (Panthera tigris altaica) in the Russian Far East, canine distemper virus (CDV) has been repeatedly identified as a threat to wild carnivores. Between 2020 and 2022, six Indian leopards (P. pardus fusca) presented to Nepali authorities with fatal neurological disease, consistent with CDV. Here, we report the findings of a serosurvey of wild felids from Nepal. A total of 48 serum samples were tested, comprising 28 Bengal tigers (P. t. tigris) and 20 Indian leopards. Neutralizing antibodies were identified in three tigers and six leopards, equating to seroprevalences of 11% (CI: 2.8–29.3%, n = 28) and 30% (CI: 12.8–54.3%, n = 20), respectively. More than one-third of seropositive animals were symptomatic, and three died within a week of being sampled. The predation of domestic dogs (Canis lupus familiaris) has been posited as a potential route of infection. A comparison of existing diet studies revealed that while leopards in Nepal frequently predate on dogs, tigers do not, potentially supporting this hypothesis. However, further work, including molecular analyses, would be needed to confirm this.

Impaired innate and adaptive immune responses are evidenced throughout the course of PRRSV infection. We previously reported that interleukin-1 receptor antagonist (IL-1Ra) was involved in PRRSV-induced immunosuppression during an early phase of infection. However, the exact mechanism associated with PRRSV-induced IL-1Ra immunomodulation remains unknown. To explore the immunomodulatory properties of PRRSV-induced IL-1Ra on porcine immune functions, monocyte-derived dendritic cells (MoDC) and leukocytes were cultured with type 2 PRRSV, and the immunological role of IL-1Ra was assessed by addition of anti-porcine IL-1Ra Ab. The results demonstrated that PRRSV-induced IL-1Ra reduced phagocytosis, surface expression of MHC II (SLA-DR) and CD86, as well as downregulation of IFNA and IL1 gene expression in the MoDC culture system. Interestingly, IL-1Ra secreted by the PRRSV-infected MoDC also inhibited T lymphocyte differentiation and proliferation, but not IFN-γ production. Although PRRSV-induced IL-1Ra was not directly linked to IL-10 production, it contributed to the differentiation of regulatory T lymphocytes (Treg) within the culture system. Taken together, our results demonstrated that PRRSV-induced IL-1Ra downregulates innate immune functions, T lymphocyte differentiation and proliferation, and influences collectively with IL-10 in the Treg induction. The immunomodulatory roles of IL-1Ra elucidated in this study increase our understanding of the immunobiology of PRRSV.

Across human and veterinary medicine, vaccines against only two retroviral infections have been brought to market successfully, the vaccines against feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV). FeLV vaccines have been a global success story, reducing virus prevalence in countries where uptake is high. In contrast, the more recent FIV vaccine was introduced in 2002 and the degree of protection afforded in the field remains to be established. However, given the similarities between FIV and HIV, field studies of FIV vaccine efficacy are likely to advise and inform the development of future approaches to HIV vaccination. Here we assessed the neutralising antibody response induced by FIV vaccination against a panel of FIV isolates, by testing blood samples collected from client-owned vaccinated Australian cats. We examined the molecular and phenotypic properties of 24 envs isolated from one vaccinated cat that we speculated might have become infected following natural exposure to FIV. Cats vaccinated against FIV did not display broadly neutralising antibodies, suggesting that protection may not extend to some virulent recombinant strains of FIV circulating in Australia.

Canine distemper virus (CDV) is recognized as a conservation threat to Amur tigers (Panthera tigris altaica) in Russia, but the risk to other subspecies remains unknown. We detected CDV neutralizing antibodies in nine of 21 wild-caught Sumatran tigers (42.9%), including one sampled on the day of capture, confirming exposure in the wild.

Duck Tembusu virus (DTMUV), an emerging avian pathogenic flavivirus, causes severe neurological disorders and acute egg drop syndrome in ducks. Currently, several clusters of DTMUV exhibiting significant antigenic variation are circulating in Asia with distinct geographical distributions. Therefore, developing vaccines based on virus clusters specific to regions is essential. To generate an effective inactivated vaccine, the virus inactivation procedure must be optimized for each virus strain. However, no information is available on the optimal inactivation protocol for cluster 2.1 DTMUV, which predominantly circulates in several Asian countries. This study aimed to determine the effect of beta-propiolactone (BPL) inactivation on the infectivity, antigenic integrity, and immunogenicity of cluster 2.1 DTMUV. Our results demonstrated that all conditions of BPL treatment (1:2000, 1:3000, and 1:4000 (vol/vol) concentration; 24, 48, and 72 h of incubation) could completely inactivate cluster 2.1 DTMUV, as evidenced by the absence of cytopathic effect (CPE) and DTMUV antigens after 3 passages in baby hamster kidney (BHK-21) cells. However, BPL at 1:4000 (vol/vol) concentration with 24 h of incubation preserved both the total protein content and the antigenic integrity of cluster 2.1 DTMUV more effectively than other conditions. Furthermore, we found that cluster 2.1 DTMUV inactivated with BPL under this condition was safe and highly immunogenic in ducks. This was evidenced by the absence of clinical signs and the robust induction of DTMUV-specific neutralizing antibodies and T helper lymphocyte responses in immunized ducks. Overall, these findings suggest that a 1:4000 dilution of BPL with 24 h of incubation is the optimal condition for complete inactivation of cluster 2.1 DTMUV without significant loss of antigenicity and immunogenicity. This protocol can serve as a guideline for efficient cluster 2.1 DTMUV inactivation, which is valuable for vaccine and immunoassay development.