First Molecular Characterization of Small Ruminant Lentiviruses Detected in Romania

Abstract

Small ruminant lentiviruses (SRLVs) are a group of retroviruses that cause multisystem chronic diseases in goats and sheep and lead to production losses in these animals, negatively affecting animal health and welfare. Although molecular characterization of SRLV field isolates has been performed in many countries, there is currently no information on SRLV genotypes circulating in sheep and goats in Romania. Therefore, the main objective of this study was to conduct a molecular and phylogenetic analysis of SRLVs from Romania and determine the degree of genetic relatedness of the obtained sequences to other known SRLV reference strains. A total of 81 sheep lung tissue samples and 41 sheep lung lymph node samples were tested using nested real-time PCR, and samples positive for real-time PCR were used to amplify an 800 bp gag-pol fragment and an overlapping 625 bp fragment of the gag gene. Pairwise DNA distance and phylogenetic analysis showed that the Romanian SRLV strains were closely related to the A2 and A3 strains based on gag-pol sequences and to the A3 and A17 subtypes based on gag sequences. No recombination events were found. Our results revealed that the Romanian sequences have similar epitope patterns to other existing subtypes, although E/K and R/K mutations in epitope 3 were found only in the Romanian sequences, which may have potential value in serological diagnosis. This study is the first report on the genetic characterization of SRLV strains circulating in Romania and provides new information on SRLV heterogeneity. Further detailed studies should be conducted to better understand the divergence of SRLV Romanian strains.

Genetic Characterization of Small Ruminant Lentiviruses Isolated from Dairy Sheep in Greece

“…A previous study in our country analyzed shorter amino acid sequences, including only epitope 2 and the MHR [24], without, however, comparing the specific regions of epitopes, instead comparing the total amino acid sequences. Our findings confirmed the presence of the asparagine-valine "NV" and the double glycine "GG" motifs clustered in genotypes A and B, respectively, as previously described in similar studies [34,39,49,54,60,61]. Also, epitopes 2 and 3 were found highly conserved when the strains of genotype A from the present study were compared to the reference strains of the same clade, with the exception of one isolate (s-42fl) in which three new amino acid replacements were identified [one conservative substitution in epitope 2 (D/E) and two non-conservative substitutions in epitope 3 (G/R and Y/S)].…”

“…This is the first time that an extended gag - pol fragment (~800 bp), including all the immunodominant regions of capsid protein, from SRLV strains isolated in Greece is analyzed for their genetic characterization. Although numerous sequencing and phylogenetic analyses have been performed for the genotyping and classification of SRLV strains worldwide, based on different regions of the viral genome (mainly gag , pol , and env genes) [ 5 , 6 , 7 , 8 , 9 , 13 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ], phylogenetic data regarding circulating SRLV strains in Greece are limited and derived from previous studies based on partial pol (~390 bp) [ 25 , 26 ] and gag (574 bp) [ 24 ] sequences, which in the latter case did not include all the immunodominant regions of capsid protein in contrast to our study.…”

“…Immunodominant epitopes of capsid protein have been previously characterized in many studies for the assessment of their heterogeneity [ 6 , 7 , 9 , 24 , 34 , 51 , 52 , 53 , 54 ]. Considering that immunodominant linear epitopes of capsid protein are strongly associated with the type-specific host immune response [ 46 , 53 , 55 ], their role in serological diagnosis is crucial.…”

Serological and Molecular Characterization of Small Ruminant Lentiviruses in Morocco

“…In particular, the diagnosis of SRLV infections is complicated by the high variability of circulating strains, since no serological tests that are able to discriminate all the possible viral variants are available to date [6]. This limitation was partially overcome by combining the ELISA tests with molecular tools that employed degenerate primers that are able to detect a wide number of subtypes [5,[7][8][9][10][11][12][13][14][15][16]. Moreover, in the recent years, novel untargeted molecular techniques have been successfully applied to the study of the genetic diversity and evolution of SRLV strains [17,18].…”