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Small ruminant lentivirus (SRLV) infections are widespread in Greece, but SRLVs have never been isolated and characterized. In this study, we present the sequence of a 574-nucleotide (191-amino acid) region of the gag gene of SRLV strains from four sheep and one goat from a single geographic area of Greece. All five sequences appeared to be closely related at both nucleotide (2.1-14.2% variation) and deduced amino acid (1.6-4.2% variation) level. Greek SRLV strains were closer to ovine prototypic strains (average divergence 16.8%) than to the caprine strain CAEV-Co (21% divergence). By amino acid composition, the Greek SRLVs were on the average more than twice as distant from CAEV-Co as from other ovine strains. Phylogenetic analysis suggested that Greek strains segregate into a unique group, separate from, but related to, other ovine prototype sequences.

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Infection of cats with feline immunodeficiency virus (FIV), a naturally occurring lentivirus infection of cats which causes an AIDS-like disease, has generated considerable interest as an animal model for HIV vaccination. This paper reports on experiments performed to examine the potential of a fixed infected cell vaccine to confer protection against intraperitoneal challenge with cell-free FIV. The cell vaccine was highly immunogenic and elicited antibody responses to virus core antigen, p24, high virus neutralizing (VN) antibody titres, and antibodies which recognized cellular components of the vaccine. Whilst protection, assessed by the inability to detect infectious virus by virus isolation or polymerase chain reaction, against homologous but not heterologous FIV isolates was apparent up to week 12 post-challenge, when cats were monitored longer up to week 50 post-challenge a breakthrough in vaccine protection against homologous virus was observed. Protection could not be correlated with levels of antibody to p24 or VN antibody titres. In contrast with simian immunodeficiency virus vaccine studies in macaques there was no clear evidence that antibodies recognizing cellular components of the vaccine, including MHC class I and II antigens, conferred any protective effect following challenge. These results indicate that long-term post-challenge monitoring for infection is essential in lentivirus vaccine trials.

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The influence of dexamethasone and cyclophosphamide on the goat immune system was investigated. Seven goats, with a previous contact with caprine herpesvirus type 1 (CHV-1), were used. All had been vaccinated with live Mycobacterium paratuberculosis vaccine. Six goats were injected intravenously (i.v.) with dexamethasone daily for 5 days (2.5-4 mg/kg BW per day). Three also received 25 mg/kg BW of cyclophosphamide on day 0. The seventh goat was not treated. Dexamethasone alone caused depression, slight lymphopenia and fall in tuberculin reaction. Dexamethasone plus cyclophosphamide caused a severe clinical reaction, marked leukopenia (lymphopenia and polymorphopenia), fall in tuberculin reaction and significant increase in CHV-1 neutralizing antibody titres. M. paratuberculosis antibody reaction was variable and thus difficult to be assessed. CHV-1 was not isolated.

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The pathogenicity of caprine herpesvirus type-1 (CHV-1) in goat kids and lambs was studied. Two experiments were carried out. In the first, two Saanen goat kids and four lambs of a local breed were infected intravenously with the Swiss strain E/CH of the virus. Clinical reaction was severe in the kids, but it was very mild in the lambs. Virus was excreted from the kids in higher titres and longer than in lambs. Virus was also isolated from tissue specimens but only from a kid that died on post inoculation day 4 (PID 4). The gross- and histopathological lesions were more severe in kids. In the second experiment only lambs were used. They were dexamethasone treated and then virus inoculated. A very mild infection developed. The lambs did not shed the virus, neither the virus was isolated from their tissues collected at necropsy. Nevertheless histopathological lesions were seen. In both experiments the animals seroconverted on PID 10.

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An experiment was designed for a preliminary investigation of the caprine herpesvirus BHV-6 latency. The experiment was carried out in two steps. In the first, the virus inoculated six kids and the control, showed a mild infection and excreted the virus for 4-12 days. The second part started about one month after the cease of all symptoms and the virus isolations of the first part. No immunosuppression and therefore no virus reactivation could be achieved after eight daily administered injections of dexamethasone (0.15-0.50 mg/kg BW), as it was judged by the hematological, virological, pathological and serological findings.

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Previous preliminary studies had shown that caprine herpesvirus (BHV-6) infections exist in many countries where goats play an economical role. The extensive serum survey made in Greece reveals that the virus must be widespread because more than 50% of the goats have antibodies. The bucks were found to have a higher evidence of infections than the female goats. The kids possessing maternal antibodies became seronegative at the age of 4 months and new antibodies appeared at the age of 7-8 months. Observations in 2 closed goat herds showed that the virus does not spread during the mating and lactating period. Neutralization titres increased or new infections in seronegative animals occurred after the summer when breeding took place. The virus is present in a latent state and recurrent infections are assumed to occur. In spite of that all our efforts to isolate the virus were unsuccessful, even after experimental immunosuppression.

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