Argentine strain of equine herpesvirus 1 isolated from an aborted foetus shows low virulence in mouse respiratory and abortion models.

The equine herpesvirus 1 (EHV-1) was isolated in Argentina from an aborted equine foetus in 1979. This virus (SPv) has special restriction patterns (RP) in comparison with other Argentine isolates. In addition, SPv could be distinguished on the basis of its pathogenicity in baby mice inoculated intracerebrally. We studied the growth properties of the SPv in cell culture and its effects in a mouse respiratory and abortion model. We observed that SPv did not modify its capacity to grow in cell culture with respect to reference HH1 strain. Nevertheless, we found significant differences between the titres of the two strains at 8-14 h post-infection (PI). In this work we demonstrated that SPv showed low virulence in female at different stages of gestation, consistently, with results found in the mouse respiratory model. We considered that this low virulence of SPv could be related to its RP because the RP of HH1 strain are similar to those of the HVS25A strain and both showed effect on pregnant mice. More specific studies about genomic alterations to the SPv are necessary for identifying, more clearly, if the intra-strain variations have relation with the low virulence in the mouse respiratory and abortion model.

A polymerase chain reaction for detection of equine herpesvirus-1 in routine diagnostic submissions of tissues from aborted foetuses.

Equine herpesvirus 1 (EHV-1) is the causative agent of abortion, perinatal foal mortality, neurological and acute respiratory diseases in horses. Conventional laboratory diagnosis involving viral isolation from aborted foetuses is laborious and lengthy and requires processing of samples within 24 h of collection, which is problematic for samples that come from long distances. The aim of this study was to develop a polymerase chain reaction (PCR) assay useful in Argentina to detect DNA sequences of EHV-1 in different tissues from aborted equine foetuses with variable quality of preservation and without the use of conventional DNA fenolic extraction. Several DNA extraction protocols and primers were evaluated. The amplification method was standardized and its specificity was analysed using 38 foetal samples of variable quality of preservation. Of the 38 different foetal tissues, nine livers, six spleens and two lungs in good preservation and eight livers, one spleen and four lungs in a poor state of preservation were positive for PCR. EHV-1 was recovered only from the nine livers, five spleens and two lungs in good preservation. No virus was isolated from the samples that were poorly preserved. Viral isolation was confirmed by cytopathic effect and indirect immunofluorescence. The specificity of the PCR results was confirmed by the restriction endonuclease digestion of PCR products and hybridization.

[Indirect ELISA for the rapid diagnosis of Equine Influenza]. / ELISA indirecto para el diagnóstico rápido de Influenza Equina.

An indirect enzyme linked immunosorbent assay was developed. Infected and non infected allantoic fluids precipitated with polyetilenglycol 6000 were used as antigen and control antigen, respectively. Serum samples were diluted 1/20 and a commercial horse radish peroxidase-labelled rabbit anti-equine IgG was used as second antibody. The reaction was developed using azino-diethylbenzotyazol-sulfonate (ABTS). Cut-off was determined by ratio sample (Rs). The hemagglutination inhibition test was used as a reference test for the 391 samples analyzed. Of these, 301 sera were positive by hemagglutination inhibition test and indirect ELISA, 75 were negative by both techniques, and 15 were positive by indirect ELISA and negative by hemagglutination inhibition test. Using hemagglutination inhibition test as standard, the indirect ELISA showed a relative specificity and sensitivity of 83.3 and 100%, respectively. This indirect ELISA is useful as screening test.