Serological Characterization of Small Ruminant Lentiviruses: A Complete Tool for Serotyping Lentivirus Infection in Goat

Small ruminant lentiviruses (SRLVs) form a very heterogeneous group of ssRNA viruses able to infect goats and sheep worldwide. The genetic heterogeneity is reflected by a large antigenic variability which can represents a potential bias in serological diagnostics. Indeed the circulation of four different viral genotypes reveals how the surveillance and control of SRLV is a hard challenge. In previous works we described the use of a single subunit of the viral capsid protein for the SRLV infection genotyping. The amino acid sequence of this region was characterized for each genotype, produced in recombinant form and used as antigen in the described indirect ELISA assay. In this work we completed the panel of antigens including all the divergent genotypes. The subunits of genotypes A, B, C and E were used to test a different groups of goat sera belonging to flocks were the SRLV circulation was proven and genetically characterized. The results confirmed the ability of the P25-B3 subunit to correctly discriminate the viral infection, showing a very high concordance between the SRLV genotype circulating within the flock and the serotype identified by the ELISA test. The proposed approach is able to detect and distinguish all known SRLV genotypes detected so far in Europe. It could represent a cost effective support in SRLV identification, beside the more expensive and time consuming genetic analysis, improving the knowledge about viral heterogeneity. Finally, it may represent a first line epidemiological tool in those Countries in which SRLV have been detected but not yet characterized.