Genetic Mutations in the LTR Region of SRLV Viruses in Capra ibex

Abstract

The lentivirus (genus of the retroviruses family) can integrate a significant amount of viral cDNA into the DNA of the host cell and can efficiently infect dividing cells. They are able to spill over from their natural host species to induce new infections and pathologies among hosts of new species. This defines the crossing of species barrier that originates emergent viruses causing emergent diseases. The transmission of lentiviruses was observed between different species (domestic & wild). The small ruminant lentiviruses (SRLV) transmission is accompanied by genetic mutations in the genome of the virus. The study investigated the genetic mutations that accompany the infection and adaptation of SRLV to the new host. Genetic mutations were studied by amplifying and sequencing the Long Terminal Repeat (LTR) region.Blood samples were taken from Capra ibex living in the French Alps. Sera were tested using a commercially available ELISA. Peripheral blood mononuclear cells (PBMC) isolated on a Ficoll gradient were cultured in a macrophage differentiation medium to obtain monocyte-derived macrophage (MDM) monolayers for virus isolation. DNAs from non-cultured PBMC were used as templates for the PCR amplification of proviral DNA. PCR products (270 nt) were cloned and sequenced. Sequences were analysed using ClustalW.The alignments of the LTR fragment show three types of nucleotide mutations: replacement, addition, and deletion of nucleotide. Sequence analysis shows that the TATA box and the poly (A) site were highly conserved. The divergence of the LTR region between sequences obtained varied by 0.3 - 5.7 %. These differences were also shown by the phylogenetic tree. It can be seen that proviruses from the Capra ibex sequences are a closely related group, quite distinct from the reference sequence.