Genotyping Based on the LTR Region of Small Ruminant Lentiviruses from Naturally Infected Sheep and Goats from Mexico.

Wolfang P. S. Mendiola,Humberto A. Martínez,José L. Cerriteño,Hugo Ramírez,Jorge L. Tórtora,Sandra Cuevas-Romero,María M. García

doi:10.1155/2019/4279573

Abstract

Small ruminant lentiviruses (SRLVs) belong to the genus Lentivirus in the Retroviridae family. There are five genotypes (A, B, C, D, and E), where genotypes A and B have a global distribution and genotypes C, D, and E are limited to Europe. The presence of SRLV has been confirmed in Mexico, with genotype B detected in the central region of the country. We examined the presence of SRLVs and genotype prevalence in 1014 sheep and 1383 goats from 12 Mexican states. Using a commercial competitive ELISA (cELISA) test, we detected SRLV antibodies in 107 sheep (10.55%) and 466 goats (33.69%). We used an endpoint PCR to amplify the LTR region on seropositive animals. A total of 50 sheep and 75 goats tested positive via PCR. Positive amplicons from 11 sheep and 17 goats from ten Mexican States were cloned and sequenced. With the LTR sequence data obtained in this study, a phylogenetic analysis was performed; we also constructed a phylogenetic tree using the obtained sequences and GenBank's available sequences. All studied sequences were associated with genotype B, specifically with the FESC-752 isolate previously identified in Mexico. Highly conserved transcription factor binding sites were observed in analyzed alignments, such as AML (vis), AP-4, and TATA box. However, we identified nucleotide differences at site AP-1 that suggest function loss. Our study found that ovine and caprine genotype B SRLVs are widely distributed in Mexico; a highly conserved LTR region among the sequences evaluated in this study was also found.

Highlights

Small ruminant lentiviruses (SRLVs) are single-strandedRNA viruses grouped in the order Ortervirales, Retroviridae family, Orthoretrovirinae subfamily, and Lentivirus genus [1, 2]
Plasma was collected and stored at -70∘ C for later use, and peripheral blood leukocytes (PBL) were processed as described by Gorodezky et al [23]
We found that all sequences obtained in the study were associated with genotype B

Summary

Introduction

Small ruminant lentiviruses (SRLVs) are single-strandedRNA viruses grouped in the order Ortervirales, Retroviridae family, Orthoretrovirinae subfamily, and Lentivirus genus [1, 2]. SRLVs have three structural genes (gag, pol, and env), three accessory genes (vpr-like, vif, and rev) and LTRs at the. The LTR is composed of three regions U3, R, and U5 and have been described as viral transcription promoters, the U3 region that potentializes transcription factor binding sites [3,4,5]. LTRs can influence viral tropism in the central nervous system when specific CAAAT sequences are duplicated. Poor viral growth occurs when a single CAAAT sequence is present and no transcription occurs when CAAAT is deleted [6]. SRLV infect sheep and goats worldwide, causing multisystemic chronic and progressive infections, characterized by pneumonia, encephalitis, arthritis, and mastitis [7,8,9]. CSyntax Warning: Could not parse ligature component "0053" of "_0053" in parseCharName

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