Preparation of Type-specific Antisera to Reoviruses.

Preparation of type-specific antisera to reoviruses has been handicapped by the ubiquitous distribution of these viruses and frequent occurrence of reovirus antibodies in many species of animals. Antisera prepared in rhesus monkeys at this laboratory have shown extensive crossings between the three types (Table 1). Similar crossreactions have been observed in antisera prepared in rabbits (A. M. Lerner et al., J. Med. 267:947, 1962), and a minor cross-reactivity is detectable in chicken antisera (unpublished data). Guinea pigs have also been recommended; however, some of these animals procured from stock colonies possess reovirus hemagglutinationinhibition (HI) antibodies and, thus, upon immunization, may develop significant heterologous titers (L. Rosen, Am. J. Hyg. 71:242, 1960; L. Rosen, Diagnostic Procedures for Viral and Rickettsial Diseases, 3rd ed., p. 259, Am., Public Health Assoc., New York, 1964). Moreover, the extent of cross-reaction among guinea pig antisera by serum neutralization (SN) test has not been delineated. In our search for a species which would be normally free from preexisting antibodies and which would provide large quantities of monotypic antisera, we found the white domestic goose quite suitable. This note describes the results of preparing, in geese, type-specific antisera to the three serotypes of reovirus. Several young adult white domestic geese, weighing 10 to 12 lb each, were obtained from a farm located in the vicinity of Kansas City. The birds were bled, and their sera were tested for HI and SN titers against the three prototype strains of reovirus, namely, Lang (reo 1), Jones (reo 2), and Abney (reo 3). All sera showed HI and SN titers of less than 1:10. The immunization of these geese was started with antigens consisting of infectious monkey kidney cell culture fluids of the three prototype viruses. These cell cultures, maintained in medium 199 containing 0.5% SV5 antiserum, were infected with the reoviruses [heated in 1 M MgCl2 at 50 C for 1 hr as an aid toward destruction of simian agents possibly present as contaminants (C. Waflis and J. L. Melnick, Texas Rept. Biol. Med. 19:701, 1961)]; they were then rolled at 37 C to obtain higher infectivity and hemagglutinin titers (A. M. Lerner, J. D. Cherry, and M. Finland, Proc. Soc. Exptl. Biol. Med. 110:727, 1962). The viruses were harvested 4 to 5 days after the appearance of cytopathic effects (CPE) rated 4+ (100% of the cells showing degeneration). This delay was effected in view of our earlier observation that, although the infectivity titers remained generally unchanged, the hemagglutination titers of all three types increased considerably when infected