[Indicators of collective immunity to influenza depending on the blood group and sex of the population].

Immunological investigations of the time course of serum anti-HA and anti-NA antibodies against influenza A and B viruses in the female and male population with blood groups 0(I), A(II), B(III), and AB(IV) were carried out for several months. The persons with the blood group AB (IV) were shown to be most sensitive to influenza A and B. They were affected by the epidemic virus earlier and more severely than those with the other blood groups.

[Formation and protective functions of antibodies to neuraminidase of the influenza A virus].

The features of production and protective properties of antineuraminidase antibodies in subjects of various ages with influenza infection caused by currently important influenza A virus strains of H1N1 and H3N2 serosubtypes were studied. In children, antineuraminidase antibodies were found to accumulate less intensively than in adults and in infants under 1 year they were detected extremely rarely. In young infants, their titres after the disease decreased more rapidly than antihemagglutinin titres.

[Antineuraminidase serum antibodies in natural influenza A and immunization with influenza vaccines].

Parallel HI and virus-elution-from-erythrocytes-inhibition (a simplified method for titration of neuraminidase antibody) tests were used for examinations of 1117 blood serum specimens from 440 adults and children under study, 5250 single serum specimens from healthy subjects from birth to 65 years of age, 38 paired serum specimens from children who experienced influenza A/Texas/1/77 disease in the epidemic of 1979-1980, and 590 paired serum specimens from subjects immunized with influenza vaccines. In 7%-23% of influenza patients and immunized subjects antibody rise was observed to only one of the influenza A virus surface antigens, hemagglutinin or neuraminidase. The protective activity of antibody to influenza A virus neuraminidase was as good as that of antihemagglutinins.

[Complex study of population immunity to 3 influenza A virus antigens].

In 5 large cities of the USSR a four-year study of the population immunity to 3 antigens of influenza A virus (hemagglutinin, neuraminidase and ribonucleoprotein antigens) was carried out. The time course of immunity to these antigens had a similar character. The high level of population immunity to actual hemagglutinin and neuraminidase, observed for 2 years, in succession, indicated the possibility of shift-life changes in these surface antigens.