Caprine lentivirus in sheep milk and semen

C.C.V Lima,A.L.M Sousa,E.M Damasceno,J.F Araújo,D.A.A Azevedo,A Andrioli,R.M Peixoto,M.C.C Ayres,A.O Costa Neto,R.R Pinheiro,T.S Souza,J.N Costa,V.W.S Santos

doi:10.1590/1678-4162-8974

Abstract

ABSTRACT With the objective of detecting the presence of caprine lentivirus (CLV) in ewe milk and in ram semen, ten matrixes and four reproducers experimentally infected with CLV were used. Samples of ewe milk were collected during the four months of lactation, five collections per animal, totaling 50 samples. Regarding the rams, eight semen collections were made per animal, during one year of experimentation, totaling 32 samples. The milk and semen samples were submitted to DNA extraction and the nested polymerase chain reaction test (nPCR) to detect CLV proviral DNA. Eight (16%) of the milk samples were positive in nPCR originating from two ewes. Only one (3.12%) semen sample was positive. The amplification products were sequenced, and were confirmed to be a CLV genomic sequence. Thus, the presence of CLV proviral DNA in sheep milk and semen was demonstrated, confirming the feasibility of infection between species, and alerting to the risk of spreading infections.

Highlights

Caprine arthritis encephalitis (CAE) and ovine maedi-visna (MV) are diseases caused by small ruminant lentiviruses (SRLV), characterized by chronic evolution and progressive worsening until death (Blacklaws, 2012)
caprine lentivirus (CLV) proviral DNA was detected in the milk of ewes by the nested polymerase chain reaction test (nPCR) technique in eight out of the 50 analyzed samples (Tab. 1)
The capacity of nPCR for detecting proviral DNA in milk was verified in other studies (Gregory et al, 2011; Sardi et al, 2012); but they worked with goats and there was low detection in the face of the infection, which may be justified by the possible small number of copies of the viral genome present in the milk cells since the viral load varies (Barquero et al, 2013)

Summary

Introduction

Caprine arthritis encephalitis (CAE) and ovine maedi-visna (MV) are diseases caused by small ruminant lentiviruses (SRLV), characterized by chronic evolution and progressive worsening until death (Blacklaws, 2012). Different clinical manifestations are known, the main ones being arthritis, pneumonia, encephalitis and mastitis, besides progressive weight loss (Pasick, 1998; Souza et al, 2015). Transmission may happen vertically, between the infected matrix and its offspring (Alvarez et al, 2005); horizontally, by direct contact between infected and susceptible animals (Villoria et al, 2013), and in iatrogenic way, with emphasis on artificial feeding and use of semen in reproduction techniques (Alvarez et al, 2006; Andrioli et al, 2006; Souza et al, 2013). Genomic analyzes of SRLV pointed to the occurrence of heterogeneous strains, evolved from viral prototypes of CAE and MV, able to infect both goats and sheep (Shah et al, 2004)

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Conclusion