Isolation and identification of pestiviruses in alpacas (Lama pacos) and llamas (Lama glama) introduced to the Región Metropolitana, Chile

Abstract

The natural habitat for more than 90% of the domestic South American camelids (SAC) in Chile, alpaca (Lama pacos) and llama (Lama glama), is located between 11° and 21° South latitude at 3,800 and 5,000 ms of altitude. Lately, alpacas and llamas have been introduced to other geographic parts of the country where they are in contact with domestic ruminants, making likely infection with BVDV, present in cattle, goats and sheep. The BVDV includes two species, BVDV genotype I (BVDV I) and BVDV genotype II (BVDV II), which along with the border disease virus (BDV) and classical swine fever virus (CSFV) conforms the Pestivirus genus of the Flaviviridae family. This study evaluates the hypothesis that SAC introduced to the Metropolitan Region (MR) of Chile are infected with pestiviruses. In order to perform viral isolation, samples were taken from 80 SAC (42 live alpacas, 35 live llamas, 2 dead llamas and 1 aborted foetus of llama), coming from 4 flocks suspected to be infected with pestivirus. The samples were inoculated in primary culture of bovine foetus lung cells (free of BVDV), passing each sample 5 times, and were then analyzed by direct immunofluorescence and indirect immunoperoxidase techniques to detect the presence of pestivirus antigens. For molecular characterization, a fragment of the 5-untranslated region (5-UTR) of RNA of the isolates was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and treated with restriction enzymes Pst I, Bgl I and Xho I in order to identify species of viruses. The results show that 18 SAC (10 alpacas and 8 llamas from the 4 studied flocks), were infected with pestivirus. All isolates were non cytopathogenic. BVDV I was isolated from 6 alpacas while BVDV II was isolated from 4 alpacas and 8 llamas . The viral samples were obtained from 8 healthy alpacas, 2 alpacas with abortion, 5 healthy llamas, 2 llamas with abortion and 1 dead llama without clinical history. It is concluded that alpacas and llamas from the MR of Chile are infected with BVDV I and BVDV II.