URSID γ-HERPESVIRUS TYPE 1-RELATED VIRUS IN CAPTIVE BORNEAN SUN BEARS (HELARCTOS MALAYANUS EURYSPILUS) IN SABAH, MALAYSIA.

The Bornean sun bear (Helarctos malayanus euryspilus) is the smallest subspecies of sun bear. Their numbers are declining, and more research is needed to better understand their health and biology. Forty-four bears housed at the Bornean Sun Bear Conservation Centre (BSBCC) in Sabah, Malaysia, were screened for known and novel viruses in November 2018. Ursid γ-herpesvirus type 1 (UrHV-1) is a herpesvirus that has been detected from swab samples of clinically healthy sun bears and biopsy samples of oral squamous cell carcinoma in sun bears. We detected an UrHV-1-related virus from throat and rectal swabs by molecular viral screening in samples from 15.9% of the sun bears at BSBCC. None of the bears with the UrHV-1-related virus in this study had oral lesions. There is no known report of UrHV-1 detection in the wild sun bear population, and its association with oral squamous cell carcinoma is not fully understood. Finding an UrHV-1-related virus in a rehabilitation center is a concern because conditions in captivity may contribute to spreading this virus, and there is the potential of introducing it into wild populations when a bear is released. This study demonstrates an urgent need to carry out similar surveillance for sun bears in captivity as well as those in the wild, to better understand the impact of captivity on the prevalence and spread of UrHV-1-related viruses. Positive bears also should be monitored for oral lesions to better understand whether there is a causal relationship.

Trends on Human Norovirus Virus-like Particles (HuNoV-VLPs) and Strategies for the Construction of Infectious Viral Clones toward In Vitro Replication.

Most acute gastroenteritis (AGE) outbreaks and sporadic cases in developing countries are attributable to infection by human norovirus (HuNoV), the enteric virus mainly transmitted via fecal-contaminated water. However, it has been challenging to study HuNoV due to the lack of suitable systems to cultivate and replicate the virus, hindering the development of treatments and vaccines. Researchers have been using virus-like particles (VLPs) and infectious viral clones to overcome this challenge as alternatives to fresh virus isolates in various in vitro and ex vivo models. VLPs are multiprotein structures that mimic the wild-type virus but cannot replicate in host cells due to the lack of genetic materials for replication, limiting downstream analysis of the virus life cycle and pathogenesis. The development of in vitro cloning systems has shown promise for HuNoV replication studies. This review discusses the approaches for constructing HuNoV-VLPs and infectious viral clones, the techniques involved, and the challenges faced. It also highlights the relationship between viral genes and their protein products and provides a perspective on technical considerations for producing efficient HuNoV-VLPs and infectious viral clones, which could substitute for native human noroviruses in future studies.