Characterization of new strains of Pseudorabies virus in Argentina: Detection of interspecies transmission

Abstract

Background: Aujeszky’s disease is mainly a swine disease, still endemic worldwide. It can infect other mammalians, including human beings, and it is usually fatal with nervous symptoms. Since the disease was detected in 1988 in Argentina, many outbreaks have been reported, involving both feral swine and dogs. Aim: At present, in Argentina, PRV cases are sporadically reported, however clinical cases are informed. The purpose of this study is to obtain information about the seroprevalence of PRV in wild boar and to isolate and characterize PRV from clinical samples. Methods: From 2018 to 2019, 78 wild boars serum samples from Bahía de Samborombón natural reserve were analyzed for antibodies to PRV using a virus neutralization test. Clinical samples from 17 pigs, 2 wild boar, one dog and 1 cat were collected from 2013 to 2019 for viral isolation and detecting the presence of the gD gene by PCR. For sequence analysis, the gC partial gene was amplified. Results: Five strains were isolated from the dog, cat and swine samples. The new PRV strains identified were confirmed by BLAST analysis, which revealed between 99.74 to 100% of similarity to the NIA-3 strain and phylogenetic analysis of the partial gene encoding the gC protein revealed that the PRV strains have divided into two main clades, clade 1 and clade 2. Conclusion: This report informed that most new cases of PRV were detected in the central regions of Argentina, where the pig production is concentrated. The study in Bahía de Samborombón revealed a high percentage of detection but the sampling is not representative of that of the rest of the country. Therefore, a systematic sampling effort of wild boar throughout the country should be included in the national program control. Although in Argentina only the inactivated Bartha vaccine is allowed, recombination risk should not be ignored if attenuated vaccines are incorporated into the National control plan. The two strains, one from the cat and one from the dog sample, are directly related to infected swine. The information about clinical cases and molecular characterization of new strains are important for a better understanding of the dynamics of PRV and to promote preventive measures.