Genetic and antigenic characterization of Brazilian SRLV strains: Natural small ruminant interspecies transmission from mixed herds.

Cross-species transmission events and mixed infection of small ruminant lentiviruses (SRLVs) were studied in seven goats and two sheep from three small ruminant mixed flocks from Northeast and Southeast Brazil. Genetic and antigenic analyses with gag/env genes and ELISA multiepitope SU1/SU5 recombinant antigens were carried out, respectively. The genetic analysis of gag and env sequences showed high viral diversity in both species, MVV-like (subtype A1) and CAEV-like B1 in goats, and CAEV-like (subtype B1) in sheep, revealing SRLV interspecies transmission from sheep to goats and vice versa in Brazilian farms. Two Brazilian caprine lentiviruses were segregated in two new genetic clades based on gag analyses, which suggests a new classification into heterogenic genotype A. Furthermore, goat isolates were grouped into subtype A1 and B1 clusters. Cross-reactive antibodies were detected in goats using ELISA with a recombinant antigen carrying SU1 and SU5 immunodominant epitopes; the results showed anti-CAEV and MVV antibodies in goats and anti-CAEV antibodies in sheep. This result can be associated with the high divergence in the V4 region due to SRLV variability. All results confirm cross-species infection of SRLV in Brazilian mixed herds.

Serosurvey of Schmallenberg Virus Infection in the Highest Goat-Specialized Region of France.

The monitoring of both the spread and clinical impact of Schmallenberg virus (SBV) infection within its full host range is important for the control of the epidemic and potential new outbreaks. In France, a national surveillance plan based on voluntary notifications of congenital malformations in newborn ruminants revealed that goats were the less affected host species. However, seroprevalence studies only targeted sheep and cattle, preventing accurate estimations of the real impact of SBV infection in goats. Here, a serological survey was conducted in the highest goat-specialized region of France between June 2012 and January 2013. A total of 1490 goat sera from 50 herds were analysed by ELISA. The between-herd and within-herd prevalences were estimated at 62% and 13.1%, respectively. Seroprevalence was not uniformly distributed throughout the territory and markedly differed between intensive and extensive herds. The low within-herd seroprevalence demonstrates that a large fraction of the French goat population remains susceptible to SBV infection.

Can caprine arthritis encephalitis virus (CAEV) be transmitted by in vitro fertilization with experimentally infected sperm?

For each of the five fertilization trials of the experiment, frozen semen was prepared for in vitro capacitation at a concentration of 1 × 10(7) spz/ml and divided into three groups. One group was used as a control, while the two others were inoculated with 100 µl/ml of either culture medium from non-infected cells (placebo group) or cell culture medium containing virus at a concentration of 10(5) TCID(50)/ml (infected group). A total of 789 oocytes were used for IVF. For each of the five trials a group of oocytes were used as a non-infected control and were found to be caprine arthritis-encephalitis virus (CAEV) free. The other oocytes were divided in two equal batches. Oocytes in the first batch were in vitro fertilized with CAEV infected sperm (infected group) and the second batch were fertilized with CAEV non-infected sperm (placebo and control groups). After IVF, the zygotes of each group were washed 12 times. The CAEV genome was not detected (using RT-PCR) in the washing media of either the control or placebo groups from each trial. In contrast, the first three washing media from the infected group were consistently found to be positive for the CAEV genome (5/5), whereas subsequent washing media were CAEV-free (P < 0.05). Zygotes obtained using all semen groups tested negative for both the provirus and genome of CAEV. These results clearly show that the first four washes were sufficient to remove viral particles from CAEV infected fertilization media and that CAEV-free embryos can be produced by IVF using spermatozoa infected in vitro by CAEV.

Variability and immunogenicity of caprine arthritis-encephalitis virus surface glycoprotein.

The complete surface glycoprotein (SU) nucleotide sequences of three French isolates of caprine arthritis-encephalitis virus (CAEV) were determined and compared with those of previously described isolates: three American isolates and one French isolate. Phylogenetic analyses revealed the existence of four distinct and roughly equidistant evolutionary CAEV subtypes. Four conserved and five variable domains were identified in the SU. The fine specificities of antibodies produced against these domains during natural infection were examined using a pepscan analysis. Nine immunogenic segments were delineated throughout the conserved and variable domains of SU, two of them corresponding to conserved immunodominant epitopes. Antigenic determinants which may be involved in the immunopathogenic process induced by CAEV were identified. These results also provide sensitive and specific antigen peptides for the serological detection and differentiation of CAEV and visna/maedi virus infections.

[Detection of caprine arthritis encephalitis virus in sperm of experimentally infected bucks]. / Détection du virus de l'arthrite encéphalite caprine dans le sperme de boucs infectés expérimentalement.

Shedding of caprine arthritis encephalitis virus (CAEV) was assessed in semen and blood mononuclear cells of six bucks (four boers and two saanens) experimentally contaminated with a viral strain (CAEV Cork) and on three non-infected controls. CAEV was identified by polymerase chain reaction (PCR) in blood mononuclear cells of all infected animals but only in seminal fluid and non-spermatic cells of one buck and in non-spermatic cells of another. Presence of CAEV in semen could have implications in the dissemination and control of the disease.

North American and French caprine arthritis-encephalitis viruses emerge from ovine maedi-visna viruses.

The full extent of genetic diversity among small ruminant lentiviruses (SRLVs), i.e., caprine arthritis encephalitis viruses (CAEVs) and maedi-visna viruses (MVVs), remains unknown. This is due in part to the fact that few sequences of CAEV are available. To contribute to this knowledge, gag, pol, and env nucleotide sequences from an SRLV named CA680 originating from a goat from western France were determined. This analysis revealed that this virus is closely related to the Cork and 63 CAEV American isolates. Mismatched amino acids between the CA680 virus and prototype CAEVs ranged from 6.7, 0. 7, and 17.5% for gag, pol, and SU sequences, respectively. The differences between the CA680 virus and MVV prototypes ranged from 16.5, 12.5, and 32.3% for the protein sequences, respectively. A screening using a heteroduplex mobility assay (HMA) adapted to SRLVs revealed that 6 of 10 caprine virus field isolates were closely related to CA680, indicating that this latter isolate was a prototype of CAEVs common in the west of France. Phylogenetic trees drawn using CA, RT, or SU sequences of numerous SRLVs and rooted with EIAV sequences revealed that CA680 and CAEV prototypes, all infectious for goat, clustered in one group. From these HMA and phylogenetic analyses, it appears that U.S. and French caprine SRLVs form a clade that had emerged from a much more diverse group containing all SRLVs infectious for sheep. These ovine SRLVs form a more ancient group in which the EIAV is rooted.