Serotyping versus genotyping in infected sheep and goats with small ruminant lentiviruses

• Published in: Veterinary microbiology Vol. 252; p. 108931
• Main Authors: Acevedo Jiménez, Gabriel Eduardo, Tórtora Pérez, Jorge Luis, Rodríguez Murillo, Cecilia, Arellano Reynoso, Beatriz, Ramírez Álvarez, Hugo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2021; Elsevier BV
• Subjects: ELISA; Epitopes; Genomes; Genotypes; Genotyping; Leukocytes; PCR; Peripheral blood; Phylogeny; Polymerase chain reaction; Sensitivity analysis; Serotyping; Sheep; SRLV; Mexico; Genotyping; Serotyping; PCR; SRLV; ELISA
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/j.vetmic.2020.108931

•Serotyping using a commercial ELISA correctly identified only 25.7 % of the samples genotyped using PCR-sequencing.•Sensitivity differences between two commercial ELISA phases can be attributed to different antigens being used in each phase.•Nested gag-PCRs specifically amplified genotype A or B SRLV sequences.•Sequence analysis identified genetic subtypes A1, A2, and B1 in sheep and goats infected with SRLV in Mexico. Despite SRLV infection being endemic in Mexico, there is little information regarding which genotypes are present. We compared serotyping and PCR-sequencing results from sheep and goats infected with SRLV. We separated plasma and peripheral blood leukocytes (PBL) from 1940 blood samples from sheep and goats from 12 states across Mexico. To detect SRLV infection, we tested plasma samples using two commercial ELISA kits (VMRD and Eradikit SRLV Screening). Then, we serotyped the infecting virus (A/ B) using Eradikit SRLV Genotyping. PBL DNA was used to detect the proviral genome via PCR. Positive amplicons were sequenced to identify viral genotypes using a phylogenetic analysis. Also, we analysed for residues differences in the sequences of a capsid epitope between genotypes. The serological results indicated a higher detection of seropositive animals using the VMRD ELISA compared to Eradikit, with 21 % and 15.3 % more in sheep and goats respectively. Only 25.7 % of the ELISA serotyping results matched those from PCR-sequencing. PCR-sequencing was able to identify genotype A, B and coinfections in animals classified as indeterminate by the ELISA test. This lack of sensitivity may be related to the lack of epitopes from the matrix and transmembrane peptides used by ELISA screening. Sequences analysis revealed that SRLVs found in sheep cluster with genetic subtypes A2 and B1, while those in goats cluster with subtypes A1 and B1. Serotyping did not prove to be an adequate method for predicting the viral genotype (A and / or B) in infections caused by SRLV.