First Molecular Characterization of Small Ruminant Lentiviruses in Hungarian Goat Population

Abstract

In 2023, a molecular study was conducted on the Hungarian goat population to determine genotypes and subtypes of small ruminant lentiviruses (SRLV) infecting these herds. Ten goat herds seropositive for SRLV infection according to a serosurvey conducted earlier in Hungary were selected, and 135 adult goats (>1 year old) were blood sampled. The two-stage nested real-time PCR (nRT-PCR) was used to detect proviral DNA of SRLV and distinguish between two main viral genotypes (A and B). PCR products were submitted for Sanger dideoxy sequencing, and phylogenetic and molecular evolutionary analyses were conducted on the 200-250 bp-long proviral DNA sequences from the end of long terminal repeat (LTR) region and beginning of gag gene using the MEGA11 software. Reference strains included strains most identical to Hungarian sequences according to the Standard Nucleotide BLAST and prototypic strains for the relevant genotypes and subtypes. Proviral DNA of SRLV was detected in goats from all ten tested herds. A single SRLV genotype was detected in 6 herds-genotype A in three herds and B also in three herds. In four herds, mixed infection with genotypes A and B was confirmed. In total, 110/135 seropositive goats tested positive in the nRT-PCR (81.5%): 49/110 goats (44.5%) for genotype A, 54/110 goats (49.1%) for genotype B, and 7/110 goats (6.4%) for both genotypes. Hungarian sequences belonged to subtypes A1/A18, A2, and subtype B1. This is the first study which shows that Hungarian goats are infected by SRLV belonging to both genotypes A and B.

Keywords: CAE; SRLV; caprine arthritis-encephalitis; real-time PCR.

Figure 1

Results of two-stage nested real-time PCR (nRT-PCR) performed on 135 small ruminant lentivirus (SRLV)-seropositive goats from Hungarian herds.

Figure 2

The RT-PCR cycle threshold (Ct) value of the nested real-time PCR (nRT-PCR) for small ruminant lentivirus (SRLV) genotype A and B in goats infected with a single genotype (a) and in goats co-infected with genotype A and B (b).

Figure 3

Phylogenetic tree made of 13 long terminal repeat (LTR)-gag gene sequences (length of 200-250 bp) from Hungarian small ruminant lentivirus (SRLV) strains and 9 reference SRLV strains, constructed using the neighbor-joining cluster method. Evolutionary distances calculated using Tamura-Nei method are reported above the horizontal branches and bootstrap support values (in %) are presented next to the nodes of the phylogenetic tree.