Rapid diagnosis of pseudorabies virus infection in swine tissues using the polymerase chain reaction (PCR)

In Argentina pseudorabies is an endemic disease. Routine diagnosis is made by virus isolation. It is a very long procedure to carry out and gives variable results depending on the quality of sample, hence the need for effective techniques, which are rapid and not dependent on the isolation of infectious virus. The polymerase chain reaction (PCR) technique has provided a sensitive, specific and rapid mean to detect DNA sequences. This study describes a PCR method for detection of pseudorabies virus sequences in swine tissues. In order to determine the presence of suid herpesvirus-1 DNA and antigens, 36 tissue samples collected from 19 dead pigs, with signs of pseudorabies infection, were examined by PCR, virus isolation and indirect immunofluorescence, respectively. Fifteen out of 19 pigs were positive at least for one tissue by PCR (15/19) while only three pseudorabies virus strains were isolated (3/19). All the amplified products were identified by digestion with Sa/l and hybridization. The method described herein circumvents tedious viral isolation and DNA purification and would be a valuable tool for rapid diagnosis, since it would take less than 5 h to reach an accurate result even in poorly preserved tissue samples.

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

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.

Diversity of genomic electropherotypes of naturally occurring equine herpesvirus 1 isolates in Argentina

The genomes of 10 equine herpesvirus 1 (EHV-1) strains isolated in Argentina from 1979 to 1991, and a Japanese HH1 reference strain were compared by restriction endonuclease analysis. Two restriction enzymes, Bam HI and Bgl II, were used and analysis of the electropherotypes did not show significant differences among isolates obtained from horses with different clinical signs. This suggests that the EHV-1 isolates studied, which circulated in Argentina for more than 10 years, belong to a single genotype

Características morfológicas de las placas de lisis producidas por la cepa SP1 del virus Herpes equino tipo 1 / Morphological characteristics of lytic plaques produced by the SP1 strain of the equine herpervirus type 1

Se comparó la morfología de las placas de lisis producidas pro tres cepas de virus Herpes equino tipo 1: SP1, aislada en nuestro laboratorio, y dos cepas de referencia, Kentucky B adaptada a cultivos celulares (Ky Bcc) y Kentucky B atenuada por pasajes en hamster (Ky Ba). Se observó que la cepa Ky Bcc formó placas pequeñas de tamaño variable, de aproximadamente 1 mm de diámetro y de bordes irregulares. La cepa Ky Ba formó placas de tamaño uniforme de aproximadamente 2-3 mm y bordes lisos. La morfología de las placas formadas por la cepa SP1 fue coincidente con Ky Bcc. Se concluye que la cepa SP1 es una cepa salvaje de origen abortigénico y semejante a la cepa Ky Bcc en su propiedad de formar placas líticas

Estandarización de una microtécnica de hemoaglutinación pasiva para la detección de anticuerpos contra rinotraqueitis infecciosa bovina / [Standardization of a microtechnic for passive hemagglutination to detect antibodies against infectious bovine rhinotracheitis]

A micromethod for passive Hemagglutination is described for the detection of IBR antibodies in serum samples of nine herds. The samples correspond to different zones of the province Buenos Aires. In animals without clinical signs the proportion of positives was 43.60

; in herds with signs consistent with the disease, this value attained 66.4

positivity (Tables 1 and 2). The feasibility of this method is discussed. Some variants introduced into the original technique are described.