Gas chromatographic detection of in vivo activity of equine infectious anaemia virus.

Abstract

By making use of the marked response of the electron capture detector, it has been possible to detect the presence of extremely small numbers of bacteria in culture media by gas chromatography (B. M. Mitruka and M. Alexander, Appl. Microbiol. 16:636, 1968). The same technique has been employed for the detection of canine viruses in vitro and in vivo (B. M. Mitruka et al., Science 160:309, 1968). It has now been observed that electron capture-gas chromatographic techniques can be applied to the rapid detection of the in vivo activity of equine infectious anaemia virus. Latent infections caused by this virus can only be shown by the inoculation of infective blood into susceptible horses. Serum samples from five healthy experimental horses were taken at occasional intervals for a 2to 3-month period and at 2-day intervals during the 2 weeks immediately prior to infection. The animals were then inoculated intravenously with 5.0 ml of infective serum from clinical sources. For chromatographic analysis, 2.0 ml of serum was treated with 0.10 ml of 5 N HCI and 1.0 ml of 0.2 M HCl-KCl buffer (pH 2.0); the samples were centrifuged for 15 min at 3,000 x g and the resultant supernatant fluid was extracted three times with 10 ml of ether. A 3.0-,tliter portion of the combined extract, or of the combined extract after concentration, was injected into the instrument. The chromatographic techniques were essentially the same as previously described (Y. Henis et al., Appl. Microbiol. 14:513, 1966; B. M. Mitruka and M. Alexander, Appl. Microbiol. 16:636, 1968). The animals were kept under observation for temperature elevation and changes in hematocrit readings and precipitin tests. A rise in temperature of 2 to 3 C was noted in the animals at 2 to about 4 weeks after inoculation. Animals showing illness had hematocrit readings of 20% or less as determined by packed cell volume, whereas the healthy animals showed readings of 30 to 40%.