Viral load, tissue distribution and histopathological lesions in goats naturally and experimentally infected with the Small Ruminant Lentivirus Genotype E (subtype E1 Roccaverano strain)

Abstract

Small Ruminant Lentivirus (SRLV) subtype E1, also known as Roccaverano strain, is considered a low pathogenic virus on the basis of natural genetic deletions, in vitro properties and on-farm observations. In order to gain more knowledge on this atypical lentivirus we investigated the in vivo tropism of Roccaverano strain in both, experimentally and naturally infected goats. Antibody responses were monitored as well as tissue distribution and viral load, evaluated by real time PCR on single spliced (gag/env) and multiple spliced (rev) RNA targets respectively, that were compared to histopathological lesions. Lymph nodes, spleen, alveolar macrophages and mammary gland turned out to be the main tissue reservoirs of genotype E1-provirus. Moreover, mammary gland and/or mammary lymph nodes acted as active replication sites in dairy goats, supporting the lactogenic transmission of this virus. Notably, a direct association between viral load and concomitant infection or inflammatory processes was evident within organs such as spleen, lung and testis. Our results validate the low pathogenicity designation of SRLV genotype E1 in vivo, and confirm the monocyte-macrophage cell lineage as the main virus reservoir of this genotype. Accordingly, SRLV genotype E displays a tropism towards all tissues characterized by an abundant presence of these cells, either for their own anatomical structure or for an occasional infectious/inflammatory status.

Phylogenetic analysis of small ruminant lentiviruses originating from naturally infected sheep and goats from Poland based on the long terminal repeat sequences

“…The presence of non-pathogenic SRLVs was reported in goats infected with viruses belonging to the A4 subtype, and it was evidenced that particular LTR mutations may explain their attenuated phenotype ( 1 ). The highly divergent SRLV E1 genotype was characterised in Italy as a low pathogenic caprine lentivirus, since it did not cause clinical symptoms in goats ( 6 ). Sequences of SRLVs isolated from Spanish sheep in an arthritis outbreak were assigned to subtype B2 ( 20 ), while proviral sequences isolated from Spanish sheep with neurological signs were assigned to genotype A2/A3 ( 4 ).…”

The effect of the subclinical small ruminant lentivirus infection of female goats on the growth of kids

“…virulent [36]. Therefore, it appears to be very unlikely that infection with other than A genotype could lead to any more detrimental consequences.…”

Development of in-house ELISA based on recombinant gag proteins of small ruminant lentiviruses isolated from goats in Thailand

“…SRLV can be categorized into 5 groups: A, B, C, D and E. While genotype A and B, occasionally introduced to as Maedi-visna virus-like and Caprine arthritis encephalitis virus-like, respectively, are widely distributed, whereas genotypes C and E are found in the confined areas. Genotype D was described only pol sequences while phylogenetic analysis on gag sequences of genotype D was classified these sequences into group A 3 , 4 . Previous studies have provided evidence supporting the inter-species transmission of viruses between goats and sheep 5 – 8 .…”