Browsing by Author "Pay, T. W. F"

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Dose-response relationships in a microneutralization test for foot-and-mouth disease viruses
(1977-05) Booth, J. C; Rweyemamu, M. M; Pay, T. W. F
Two-dimensional quantal microneutralization tests on foot-and-mouth disease viruses, in which neutralizing antibody activity was titrated against a serial range of virus doses, demonstrated a variety of dose-response curves some of which were rectilinear, others clearly curvilinear. Moreover, in the case of the non-linear responses obtained with some antisera, the shape of the curve was such that antibody titres recorded with doses of virus ranging from lCP-lO 5 TCD50 were closely similar. Studies were carried out on the effect of varying the con- ditions of the test on the shape of the dose-response curve: significant differences were obtained after treatment of the antiserum-virus mixtures with anti-species globulin, and when the test was assayed in cells of differing susceptibility to infection.
Microneutralization tests for serological typing and subtyping of foot-and-mouth disease virus strains
(1977-12) Rweyemamu, M. M; Booth, J. C; Head, Morwen; Pay, T. W. F
A microneutralization test for serotyping of FMD viruses is described. It is based on earlier observations by Booth, Rweyemamu & Pay (1978) that dose-response relationships in quantal microneutralizations often deviated from linearity. The typing test described therefore utilizes undiluted virus preparations. In about 90 % of samples a positive typing was obtained in contrast with about 50 % for the complement fixation test. The test was also found to be susceptible to minimal quantities of heterotypic viral contamination. For strain differentiation the microneutralization test was carried out as a checkerboard test. When compared with the complement fixation test it was found to be more specific. The necessity to utilize virus-neutralization test systems for comparing FMD virus strains particularly for the purpose of vaccine selection is emphasized. The two dimensional microneutralization test has been applied to a study of comparing FMDV vaccine strains for Europe, South America, the Middle East and East Africa.