No abstract

Antigenic components of Mahoney strain (poliovirus type 1) involved in virus neutralization reaction were analyzed with mutant Mahoney strains resistant to inhibitors in equine serum (inhibitorresistant mutants) by means of the kinetic neutralization test. It was shown that absorption of antiMahoney serum with five inhibitor-resistant mutants yielded sera with different antibodies, of which three had distinct specificities and two specificities possibly partly related to one of those three sera. Further, it was found that stepwise selection of Mahoney variants resistant to one, two, three and four different inhibitors resulted in gradual deviation of its antigenic composition from that of the original strain. From these results, the possible presence of three or more distinct antigenic determinant sites on the surface of Mahoney strain was indicated.Although the complexity of poliovirus antigen is suggested by the intratypic serologic differences among strains [3,6,13,18,19,20], the antigenic components constituting poliovirus antigen and the mode in which each of these components participates in virus neutralization reaction are still poorly understood.Previously we reported that by propagating Mahoney strain in cell cultures in the presence of poliovirus inhibitors (i.e., equine serum factors inactivating poliovirus), five different inhibitor-resistant mutants were obtained [17]. Further, antibody absorption tests with these mutants demonstrated the presence in anti-Mahoney serum of at least five antibodies with different specificities. In these experiments, however, antibody activity was measured by the 50% plaque reduction method. In the present study, in contrast, the antigenic constitution of Mahoney strain and the mechanism of virus neutralization with specific antiserum were analyzed by means of the kinetic neutralization test. MATERIALS AND METHODSVirus and cell cultures. Mahoney strain of type 1 poliovirus was used. The virus was purified by three successive plaque isolations and then grown in quantity in monkey kidney stable (MS) cell cultures with Eagle's minimum essential medium (MEM) without animal serum. The infected cell culture fluid was centrifuged at 2000 rpm and the supernatant stored in small aliquots at -20 C.Plaque assay. Monolayers of MS cells in 70-mm petri dishes were inoculated with 0.4 ml per dish of virus. After incubation for lhr at room temperature, the cell layers were overlayed with 8 ml of Eagle's MEM containing 1.1 % Bacto-agar and antibiotics. The dishes were incubated at 37 C in a humidified atmosphere of 5% CO2 and air. A 4 ml of second overlay medium containing 0.01 % neutral red was added 2 days later, and plaques counted after an additional incubation period of 6-8 hr.Anti-Mahoney serum. Hyperimmune serumRequests for reprints should be addressed to Dr.

SummaryPoliovirus inhibitors present in normal equine and bovine sera were studied by means of radioimmunoeleetrophoresis and column chromatography. The inhibitors in individual equine sera were identified as either one of the three immunoglobulins, yM, yA(T) and yG, or mixtures of them, while those in bovine sera were found to be either one of yM and yG globulins, or the mixture of the two.The inhibitors belonging to different classes of immnnoglobulin differed in their mode of action against the virus, yM inhibitors were characterized by distinct activities in the kinetic neutralization and the plaque reduction tests. In contrast, yA(T) inhibitors were highly active in the plaque-reduction and the precipitationin-agar-gel tests, although they were inactive in the kinetics of neutralization. There were two types of yG inhibitors. One did not neutralize the virus in the kinetic test, despite its distinct virus-precipitating activity. The other could neutralize but not precipitate the virus in vitro.Avidity of the inhibitors as revealed by dissociation of virus-inhibitor complexes at acidic pH's also differed among the immunoglobulin classes of the inhibitors. The complex formed with the NaIO4-treated yA(T) inhibitor was most stable and was not dissociated even at pH as low as 2.0.

SUMMARY : Cynomolgus monkeys were fed with a virulent strain of type 1 poliovirus (Mahoney), and the site of initial multiplication of the virus in the alimentary tract was investigated immunofluorescently.The virus antigen appeared as short as 24 hr after the feeding in both the squamous epithelial cells of the oropharynx and the macrophages of lymphatic structure of the tonsils. The virus antigen was also detectable at the early stage of infection in the reticulo-endothelial cells of the lamina propria of the intestines.Multiplication of poliovirus in the endothelial cells was substantiated by electron-microscopic demonstration of a characteristic crystalline inclusion consisting of poliovirus-like particles in the cytoplasm of the cells. No convincing evidence supporting multiplication of the virus in the mucosal epithelium of the intestines was obtained.Macrophages with intracytoplasmic fluorescence appeared abundantly after the onset of viremia in the lymph nodes, the spleen and the liver. Poliovirus antigen appeared after the onset of paralysis in the central nervous system, particularly in high concentrations in the motor nerve cells of the spinal cord. Poliovirus antigen was also detectable in inflammatory cells, principally the neutrophilic leucocytes, of various tissues at the late stage of infection.

SUMMARY:The age distribution of rotavirus antibody in the serum of inhabi tants of Laos and Indonesia was studied by the neutralization test using antigenically related calf rotavirus (NCDV) as a substitute for non-cultivable human rotavirus. The results revealed that both the rate of antibody-positives and the modal titers of antibody distribution by each age group in these countries were higher than those in respective age groups of Japanese, which suggest higher endemicity of rotavirus infection in these countries.A survey of rotavirus in diarrheic patients' stools by enzyme-linked immunosor bent assay indicated that the virus infection occurred most frequently among infants between 4 and 12 months of age.