RESUMO
Among animal lentiviruses, Feline immunodeficiency virus (FIV), Equine infectious anaemia virus (EIAV) and Small ruminant lentiviruses (SRLV) are important pathogens associated with a variety of clinical pictures including immunodeficiency, anaemia, arthritis, pneumonia. The detection of viral antibody response represents a practical diagnostic approach in all lentivirus infections since they remain detectable long life. Capsid antigen (CA) is the major viral core protein and specific antibodies against this antigen are usually first recognised in infected sheep, goat and horse, remaining detectable for long period. Transmembrane (TM) domain of envelope glycoprotein contains a well conserved motif known to form an immunodominant epitope in several lentiviruses. In this study a simple strategy was developed to express the entire CA and the TM epitope in a single fusion protein from equine, feline and small ruminant lentiviruses in prokaryotic system and evaluated the diagnostic utility of a purified preparation in an indirect ELISA for each of the three infections. Results demonstrate that, for FIV and SRLV infections, the combination of CA and TM fractions increases the sensitivity of diagnostic tests based only on CA. The corresponding CA/TM antigen from EIAV showed excellent agreement with Coggins test.
Assuntos
Anticorpos Antivirais/sangue , Proteínas do Capsídeo/imunologia , Ensaio de Imunoadsorção Enzimática , Infecções por Lentivirus/veterinária , Lentivirus/imunologia , Proteínas do Envelope Viral/imunologia , Motivos de Aminoácidos , Animais , Antígenos Virais/genética , Antígenos Virais/imunologia , Proteínas do Capsídeo/genética , Gatos , Epitopos/genética , Epitopos/imunologia , Anemia Infecciosa Equina/diagnóstico , Síndrome de Imunodeficiência Adquirida Felina/diagnóstico , Doenças das Cabras/diagnóstico , Cabras , Cavalos , Vírus da Imunodeficiência Felina/isolamento & purificação , Vírus da Anemia Infecciosa Equina/isolamento & purificação , Lentivirus/isolamento & purificação , Infecções por Lentivirus/diagnóstico , Infecções por Lentivirus/virologia , Lentivirus Ovinos-Caprinos/isolamento & purificação , Estrutura Terciária de Proteína , Proteínas Recombinantes de Fusão/imunologia , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/genéticaRESUMO
Equine arteritis viruses (EAV) from Europe and America were compared by phylogenetic analysis of 43 isolates obtained over four decades. An additional 22 virus sequences were retrieved from GenBank. Fragments of the glycoprotein G(L) and the replicase genes were amplified by RT-PCR, prior to sequencing and construction of phylogenetic trees. The trees revealed many distinctive lineages, consistent with prolonged diversification within geographically separated host populations. Two large groups and five subgroups were distinguished. Group I consisted mainly of viruses from North America, whilst group II consisted mainly of European isolates. In most instances, where the geographic origin of the viruses appeared to be at variance with the phylogenetically predicted relationships, the horses from which the viruses were recovered had been transported between Europe and America or vice versa. Analysis of the replicase gene revealed similar phylogenetic relationships although not all of the groups were as clearly defined. Virus strains CH1 (Switzerland, 1964) and S1 (Sweden, 1989) represented separate 'outgroups' based on analysis of both genomic regions. The results of this study confirm the value of the G(L) gene of EAV for estimating virus genetic diversity and as a useful tool for tracing routes by which EAV is spread. In addition, computer-assisted predictions of antigenic sites on the G(L) protein revealed considerable variability among the isolates, especially with respect to regions associated with neutralization domains.
