Serological and Molecular Characterization of Small Ruminant Lentiviruses in Morocco

Simple Summary The characterization of small ruminant lentiviruses in autochthonous goat and sheep populations, like the Moroccan one, represents an excellent source of information to understand their evolution from domestication to present day and improve the knowledge of the genetic diversity of these viruses. Serological data confirmed a low prevalence likely due to extensive breeding and management practice in this area. However, the low rate of success of routinely used serological tests led us to suppose that divergent strains might have escaped diagnostic tools thanks to mutations' diagnostic epitopes. This hypothesis is confirmed by next-generation sequencing results, which highlighted the presence of an A subtype carrying a mismatch in the serotyping epitope. Moreover, the circulation of novel B and recombinant A/B subtypes was also revealed.Abstract Recent studies that investigated the origins of SRLV strains offered new insights into their distribution among domestic ruminants. The aim of the study was to investigate SRLV circulation in Morocco. A total of 51 farms were selected in different geographical locations and tested by screening and genotyping ELISA. Whole blood was used for DNA extraction and nested gag PCR. The sample size allowed for an estimation of prevalence lower than 20% (CI 95%). Surprisingly, a large proportion of screening-positive samples were not correctly serotyped. Sanger and NGS amplicon sequencing approaches allowed us to obtain new sequences even from difficult-to-amplify samples. The serological data support the evidence of an intrinsic difficulty of SRLV to spread, likely due to management practices. The low rate of success by genotyping ELISA led us to suppose that divergent strains might have escaped from diagnostic tools, as partially confirmed by the evidence of an A subtype carrying a mismatch in serotyping epitope. The sequence analysis revealed the circulation of novel B and recombinant A/B subtypes. This study highlights the importance of monitoring viral sequences and their evolution to develop specific diagnostic tests, particularly in countries where control measures are in place.