Serologic evidence of bat orthoreovirus in Singapore Anna Uehara1, Chee Wah Tan1, Danielle Anderson1, Lin-Fa Wang1 1Duke-NUS Medical School, Programme in Emerging Infectious Diseases
Pteropine orthoreovirus (PRV) is a member of the Reoviridae family and known to cause respiratory and gastrointestinal complications in humans. First isolated from Australian bats in 1968, it was not until 2006 when the first human cases of PRV were reported in Malaysia. Since then, multiple countries in Southeast Asia have reported varying degrees of PRV seropositivity with seroprevalence ranging from 4.4-13%; however, no reports have come from Singapore. We sought to address whether members of the Singapore population have been exposed to PRVs through a retrospective study. In lieu of using enzyme-linked immunosorbent assay (ELISA), we adopted the Luciferase Immunoprecipitation System (LIPS) - a previously reported antibody detection method that utilizes crude lysate and requires minimal sera input. Following previously published methodology, we generated LIPS constructs against two strains of PRV and screened a cohort of patients with febrile illness in Singapore. Individuals that were deemed positive for at least one PRV strain on LIPS were further tested through serum neutralization assays, leading to a total of seven individuals with neutralizing antibodies against one of the PRV strains, PRV3M - also known as Melaka virus. These results indicate that spillover event(s) may have taken place as early as 2006, a logical finding, given the geographic proximity of Singapore to Malaysia, where PRV was first isolated from humans in 2006. Patients enrolled in the cohort presented with febrile illness, while PRV is known to cause respiratory and gastrointestinal symptoms, hence our findings are likely an underrepresentation of the PRV seropositivity in Singapore. We demonstrate that LIPS is an appropriate tool for rapid detection of antibodies with high level of sensitivity. Although ELISAs remain to be the gold standard in serology, LIPS provides a rapid alternative that negates the need for protein purification. This is especially crucial for pathogens that do not have well-established serological assays. Additionally, as the LIPS assay does not require a secondary antibody for detection, the same assay can be used for surveillance of zoonotic infections in both human and animal samples.