Poliovirus precipitins; a study by means of diffusion in agar

The in vitro determination of the D antigens of poliomyelitis viruses. I. The gel diffusion tes

1. A technique for the measurement of poliomyelitis virus D antigens by means of gel diffusion tests against antisera obtained from hyperimmunized calves is described in detail.

2. The precision of the method was estimated by performing several replicate tests with three or four dilutions of concentrated antigen of each of the three types. The D antigen content, if measured by means of twelve precipitation hexagons in agar can be calculated with a precision of about 10 per cent (95 per cent confidence limits).

3. The calf sera gave no precipitation with C antigens in the concentrations suitable for measuring D antigens.

4. The local reference antigens, the D antigen concentrations of which were adjusted to equal that of the reference antigens used in the Glaxo Laboratories, contained C as well as D antigens. This was observed in gel diffusion tests with specific anti-C sera from guinea-pigs.

5. The guinea-pig anti-C sera showed a precipitation with the immune calf sera as well as with normal calf serum. This indicated the presence of anti-calf antibodies in the guinea-pig sera, presumably elicited by traces of calf proteins in the vaccines. These antibodies might give rise to non-specific precipitation if antisera used in the test for D antigen were obtained from animal species other than those used to provide components in the tissue culture medium from which the antigens were derived.

Use of the agar diffusion precipitation test in the diagnosis of hog cholera

The application of the agar diffusion precipitation (ADP) test for diagnosing hog cholera was investigated. The test used as antigen, pancreatic tissue from 272 pigs that had been inoculated with hog cholera virus. The test was positive for 13.5% of the animals that were sick for 4 days or less, 40% of those sick for 5 days, and 77% of those sick for 6 days or more. The test was positive for 13.5% of all animals that had been vaccinated with crystal violet-glycerol hog cholera vaccine and had been sick for at least 6 days after challenge inoculation. Titration of the virus in ADP-test-negative and ADP-test-positive pancreatic suspensions did not show a direct correlation between the infective virus particle and the precipitating antigen.

A precipitin test for acute poliomyelitis and for assessing antibody response to oral poliovaccine

A description is given of a precipitin test, using potent non-infectious antigens, which can be performed in laboratories not specializing in virology. Trial of the method as a diagnostic procedure gave positive results in 100% of a series of 50 patients with acute poliomyelitis. Precipitation lines, almost always sharply defined and intense, were obtained in 89% of 33 sera within 3–8 days of onset of acute poliomyelitis and in all sera after the 8th day. In positive cases precipitation bands usually appeared within 24 hr. after starting the test. In all instances precipitation was homotypic with the type virus isolated from stools. Double bands appeared in very recent cases but only with homotypic precipitins. Single heterotypic lines appeared in 12 cases due to previous infection or perhaps due to infection by virus strains with common antigens. All control patients with nervous system disease other than poliomyelitis or with infection by Coxsackie or ECHO viruses and all control test animals gave negative results. Of 240 poorcommunity schoolchildren who had taken monovalent oral poliovaccine 4½ months previously, 80% had precipitins for Type 1, but less than 5% showed marked reactions. The sera from the remainder gave only weakly positive results. Contrasting with transience of precipitins, neutralizing antibodies persisted in nearly 100% of children tested.

The precipitin test was used to study antibody response to ingestion of trivalent oral vaccine (prepared and issued by the Poliomyelitis Research Foundation, Johannesburg). More than half (54 %) of 90 students who received the vaccine had positive precipitin-test results; most often these results appeared during the 2nd week after ingestion. In this positive group 54 % showed multiplication of at least two types and 12 % showed multiplication of all three types poliovirus.