Antigenic Analysis of Influenza Viruses by Complement Fixation

[摘要] A comparison was made of the usefulness of type-specific, soluble (S) and strain-specific, viral (V) antigens in the serodiagnosis of Asian (A2), and, to a lesser extent, of A1 influenza patients.It was found that V antigens composed of virus identical with, or closely related to, the infecting agent provide diagnostically significant answers in all patients provided the acute and convalescent stage sera are collected at appropriate times. The appearance of antibodies to a new V antigen may require at times more than 2 weeks following onset of illness.Conclusive diagnostic antibody responses may be measured with homologous V antigens even under conditions where the S-antigen fails to provide an answer; that is, a) in infants and children under 5 years of age, who often do not respond with anti-S; and b) in those patients of all ages, who possess relatively high levels of anti-S in the first serum so that no significant increments become detectable in the second.Many patients show concomitant rises in antibodies to V antigens of strains which had been circulating in earlier years, even though no antigenic relationship may be demonstrable in vitro between the test and infecting viruses. Such heterologous anti-V responses are, as a rule, lacking, or no longer measurable under the same conditions in which S antigen is found to be inadequate.A screening test has been described for rapid evaluation of numerous sera during epidemics and found suitable for a service laboratory which often receives bloods collected at times other than optimal. If the acute and convalescent stage sera are taken early; i.e. , within the first few days and 2 weeks after onset of illness, respectively, often only the S antigen (or V antigen of an earlier strain) may afford an answer. If the paired sera are collected late; i.e. , about 1–2 and 3–4 weeks after onset, only the homologous V antigen may still provide diagnostically significant results. These differences are explained on the basis that recall of antibodies to S antigen and V antigens of earlier strains is rapid in patients who had previous experiences with influenza antigens, whereas antibodies to a new V antigen develop at a slower rate.The complement-fixation test has none of the difficulties inherent in the hemagglutination-inhibition and may be employed to advantage for strain-specific serodiagnosis.

[学科分类] 生物科学（综合）