SEROPREVALENCE AND MOLECULAR CHARACTERIZATION OF FERLAVIRUS IN CAPTIVE VIPERS OF COSTA RICA.

Ferlaviruses (FV, previously referred to as ophidian paramyxoviruses, OPMV), are enveloped viruses with a negative-strand RNA genome, affecting snakes in captivity worldwide. Infection is characterized by respiratory and nervous clinical signs and carries high mortality rates, but no specific treatment or vaccine is currently available. Costa Rica has 16 species of vipers, found in captivity in collections essential for antivenom production, reintroduction, and public education. FV circulation in these populations was previously unknown, and the risk of introducing the viruses into naïve collections or free-ranging populations exists if the virus's presence is confirmed. The objective of this study was to determine seroprevalence and FV shedding in 150 samples from captive vipers in nine collections across Costa Rica. A hemagglutination inhibition (HI) assay was performed to determine the antibody titer against two Ferlavirus strains, Bush viper virus (BV) and Neotropical virus (NT), and reverse-transcriptase polymerase chain reaction (RT-PCR) and sequencing to determine virus secretion in cloacal swabs. Ferlavirus strains were replicated in Vero cells, and chicken anti-FV polyclonal antibodies were produced and used as a positive control serum for the HI. Results demonstrate that seroprevalence of anti-FV antibodies in viper serum was 26.6% (n = 40) for the BV strain and 30% (n = 45) for the NT strain in the population tested. Furthermore, molecular characterization of FV group A was possible by sequencing the virus recovered from three cloacal swabs, demonstrating circulation of FV in one collection. This study demonstrates for the first time serological evidence of FV exposure and infection in vipers in captivity in Costa Rica, and suggests cross reactivity between antibodies against both strains. Appropriate biosafety measures could prevent the spread of FV between and within collections of reptiles in the country.