Demonstration of Coinfection with and Recombination by Caprine Arthritis-Encephalitis Virus and Maedi-Visna Virus in Naturally Infected Goats

Abstract

Recombination of different strains and subtypes is a hallmark of lentivirus infections, particularly for human immunodeficiency virus, and contributes significantly to viral diversity and evolution both within individual hosts and within populations. Recombinant viruses are generated in individuals coinfected or superinfected with more than one lentiviral strain or subtype. This, however, has never been described in vivo for the prototype lentivirus maedi-visna virus of sheep and its closely related caprine counterpart, the caprine arthritis-encephalitis virus. Cross-species infections occur in animals living under natural conditions, which suggests that dual infections with small-ruminant lentiviruses (SRLVs) are possible. In this paper we describe the first documented case of coinfection and viral recombination in two naturally infected goats. DNA fragments encompassing a variable region of the envelope glycoprotein were obtained from these two animals by end-limiting dilution PCR of peripheral blood mononuclear cells or infected cocultures. Genetic analyses, including nucleotide sequencing and heteroduplex mobility assays, showed that these goats harbored two distinct populations of SRLVs. Phylogenetic analysis permitted us to assign these sequences to the maedi-visna virus group (SRLV group A) or the caprine arthritis-encephalitis virus group (SRLV group B). SimPlot analysis showed clear evidence of A/B recombination within the env gene segment of a virus detected in one of the two goats. This case provides conclusive evidence that coinfection by different strains of SRLVs of groups A and B can indeed occur and that these viruses actually recombine in vivo.

Field evaluation of a gag/env heteroduplex mobility assay for genetic subtyping of small-ruminant lentiviruses

“…Overall, these results suggest that dual infection rarely occurs, although such events can lead to inter-subtype recombination in sheep and goats. This is consistent with a recent study showing that only two goats from a commercial flock of about 300 goats that were seropositive for SRLV reacted strongly to both group A-and group Bspecific antigens, one of them being infected with a recombinant virus carrying a mosaic A/B env sequence (Pisoni et al, 2007). The situation is quite different for other lentiviruses, particularly human and feline immunodeficiency viruses, for which dual infections and recombinant forms have been detected at an appreciable frequency (Bachmann et al, 1997;Quinones-Mateu & Arts, 1999;Robertson et al, 1995;Troyer et al, 2004).…”

“…In addition, the spread of multiple subtypes in a specific geographical region, combined with the ability of SRLV strains to cross the species barrier, may give rise to dual infection and recombination. However, only one case of dual infection and viral recombination has been reported recently in naturally infected goats (Pisoni et al, 2007), and whether interspecies transmission contributes to the evolution of genetic and biological properties of SRLV isolates is currently unknown.…”

Development and comparison of strain specific gag and pol real-time PCR assays for the detection of Visna/maedi virus

“…In the present study, real--time assays were developed for two genes, gag and pol, to compare and confirm the results obtained with each individual gene. Based on the observation that the genetic variability of lentiviruses occurs not only among isolates but also within a single isolate during in vitro cultivation or during the course of the infection ( Balfe et al, 1990, Pisoni et al, 2007, Sargan et al, 1991, real--time amplicons were designed based on the consensus sequences of several gag and pol clones representative of EV1 stock variants. Both gag and pol dual labelled probe PCRs had a sensitivity sufficient to amplify the most diluted standard templates (3 copies/reaction).…”

Use of serological diagnostic techniques in the control and eradication of caprine arthritis encephalitis: an update

“…This knowledge changed the approach of the epidemiological aspects of the disease as well as its control and eradication. As a result, the etiologic agent of CAE has been referred to as small ruminant lentivirus (SRLV) (BERTONI, 2007;QUASSO;MORONI, 2005;PISONI et al, 2007;GJERSET et al, 2009).…”

“…The CAE virus (CAEV) and Maedi-Visna virus (MVV) compose the group of small ruminant lentiviruses, which are antigenically related but genetically distinct (PISONI; QUASSO; MORONI, 2005;PISONI et al, 2007;ICTV, 2013). Sheep and goats reared together can be infected with both CAEV and MVV circulating in the herd.…”