Serological responses to whole and split A/New Jersey vaccines in humans and mice following priming infection with influenza A viruses

Experiments were performed in mice to investigate the role of previous infection on responses to A/NJ/76 vaccines. Results from human studies have demonstrated that the serological responses to A/NJ/76 vaccines varied according to the age of the vaccinee and appeared to be related to their previous exposure to the different strains of influenza A virus. Mice were infected with influenza A viruses representative of the major strains (Hsw1N1, HON1, H2N2, H3N2) and later inoculated with varying doses of whole or subunit A/NJ/ML virus vaccines. Results from these experiments demonstrated a low antigenicity in non-primed mice of the subunit vaccine compared to whole-virus vaccine, but that the antigenicity of both vaccines was enhanced in mice primed by previous infection with earlier H0 and H1 viruses. The responses of heterotypically primed mice were qualitatively similar to those of primed humans following A/New Jersey vaccination.

The Elimination of Herpes Simplex Plaques by Antibody and the Emergence of Resistant Strains

Established type 1 HSV plaques were eliminated by antibody. Antibody had to remain in contact with infected cells for several days to have a maximum effect. It did not prevent the production of viral induced antigens in a cell when applied after the cell was infected but did prevent the transmission of infection to contiguous cells. Strains which were resistant to elimination by antibody formed syncytia, did not grow to significantly higher titers than nonresistant strains, and were as easily neutralized by antiserum as nonresistant strains.

The elimination of herpes simplex plaques by antibody and the emergence of resistant strains

Established type 1 HSV plaques were eliminated by antibody. Antibody had to remain in contact with infected cells for several days to have a maxi;mum effect. It did not prevent the production of viral induced antigens in a cell when applied after the cell was infected but did prevent the transmission of infection to contiguous cells. Strains which were resistant to elimination by antibody formed syncytia, did not grow to significantly higher titers than nonresistant strains, and were as easily neutralized by antiserum as nonresistant strains.

Subacute sclerosing panencephalitis: experimental infection in primates

Measles virus isolated from the brain of a 12-year-old boy with subacute sclerosing panencephalitis caused a chronic, progressive encephalitis in experimentally infected rhesus monkeys. The infection was eventually fatal in spite of pre-existing measles immunity and a vigorous secondary antibody response in serum and cerebrospinal fluid of the infected animals. The findings provide a basis for studies into the pathogenesis and possible treatment of the human disease.

Host defence mechanisms against influenza infection. II. Protection of mice with vaccines against A/Port Chalmers/1/73 and B/Hong Kong/5/72

Influenza virus strains A2/Port Chalmers/1/73 (H₃N₂) and B/Hong Kong/5/72 were adapted to mice by serial passage of virus infected mouse lungs. The adapted viruses were used to challenge mice after they had been immunized with serial dilutions of several bivalent vaccines, containing both A/Port Chalmers and B/Hong Kong antigens. Vaccines included both whole virus and split-product preparations disrupted by Tween 80 and ether (ET) or tri-N-butyl phosphate (TBP).

These bivalent vaccines induced antibodies and conferred protection to mice against challenge with approximately 30 LD₅₀ of the adapted A2/Port Chalmers virus. Significant protection against lethality (P<0·01) was observed in groups of mice which developed haemagglutinin-inhibition antibody titres of ≥1:16 following immunization. Protection was not statistically significant in groups of mice which developed antibody titres of ≤1:8 to the A/Port Chalmers/1/73 virus following immunization with higher dilutions of certain vaccines.

In a similar fashion, current bivalent vaccines containing B/Hong Kong/5/72 stimulated antibodies and conferred significant protection to immunized mice against lethal challenge with the adapted B/Hong Kong virus. Protection was demonstrated against approximately 30 LD₅₀ of adapted virus in groups of mice which developed mean antibodies of ≥1:16. Groups of mice, which developed antibody titres of <1:8 following immunization with certain dilutions of these vaccines, were not significantly protected. These studies confirm and extend observations made with formerly circulating influenza viruses, i.e. immunization with a specific inactivated vaccine in adequate dosage confers protection against a challenge dose of virus lethal to unimmunized mice.

Regulatory approach toward vaccines against cancer: the benefit/risk ratio

Decisions regarding investigational new drug applications for testing of all biologicals to be used in humans, including those designed to prevent or treat cancers, must be considered in terms of benefit/risk ratios. In order for a regulatory organization to make the appropriate decision regarding the testing of new biologicals in humans, it must have an extremely broad dialog within the critical scientific public and the general public, which are represented on committees functioning in the Bureau of Biologics. There must be a generaly consensus regarding the benefit/risk ratio of proposed new biologicals for scientific progress and the effective regulation of biologicals.

Influenza virus infection in nude mice

The role of T-cell function in influenza virus infection was studied by aerosol infection of nude mice with an influenza A virus (PR-8 strain). Nude mice died somewhat later than normal mice, and the antibody response of nude mice to the virus was minimal. Furthermore, nude mice did not eliminate the virus, which persisted for relatively long periods (two to three weeks).

Reduction of endotoxin levels in influenza virus vaccines by barium sulfate adsorption-elution

The level of endotoxin in influenza virus vaccine lots was reduced 10- to 20-fold after barium sulfate adsorption-elution. The amount of viral antigen lost was negligible.

Host defense mechanisms against Herpes simplex virus. I. Control of infection in vitro by senstized spleen cells and antibody

Sensitized mouse spleen cells decrease the spread of herpes simplex virus infection in cell culture lines derived from human and murine tissues. These washed, sensitized cells act alone and additively in combination with antibody to diminish the ability of single virus-infected cells to spread infection to contiguous cells. This control of infection is not species specific, unlike interferon, and appears to be distinct from the effect of antibody. Lymphotoxin was not detected in this lymphocyte-mediated response. This control of herpes simplex virus infection in vitro by sensitized lymphoid cells is immunologically specific; spleen cells from donor animals immunized with a heterotypic virus do not cause herpesvirus plaque size reduction. The ratio of spleen cells from immunized animals to target monolayer cells needed to produce this effect is > 4:1. Plaque size reduction of herpes simplex virus by spleen cells requires intact, immune, non-glass-adhering lymphoid cells.