[Speed and intensity of the immune response to the administration of inactivated influenza vaccine in relation to neuraminidase activity].

A comparative study of the rate of appearance of specific virus antigen in immune competent organs of mice immunized with inactivated influenza vaccine with active neuraminidase or a vaccine devoid of the neuraminidase activity was carried out by means of the immunofluorescence test and the serological tests. A considerable delay in the time (by 16--18 hours) of detection of virus antigen in cells of lymph nodes of mice as well as later (1--2 days) and less intensive (2--4-fold) production of specific virus antibody was demonstrated after immunization of mice with the vaccine without the active enzyme.

[Effective method of isolating influenza virus on chick embryos].

An effective method for isolation of influenza virus from the nasopharyngeal specimens of patients is described consisting of interruption of the virus reproduction cycle in chorioallantoic membranes of chick embryos (CECAM) at early stages of development of the infection followed by inoculation of infected CECAM homogenate into a fresh homologous medium. The new method of virus isolation is superior to the conventional one by a higher isolation rate, economy of material and time saving which is important for identification of influenza outbreaks.

[Immunogenic activity of the influenza virus dependent on ne uraminidase (author's transl)].

The immunity of mice to challenge with influenza virus was studied after immunization with killed influenza vaccine. The results showed the resistance of the animals developing early after one and two intranasal vaccinations to depend not only upon the hemagglutinating properties of the vaccine but also upon its neuraminidase activity. When mice were immunized with a vaccine the neuraminidase of which was blocked with specific antibody or inactivated by heating and formalin, the protective effect against challenge with influenza virus decreased 2-3-fold as compared to that of the vaccine possessing active neuraminidase.