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P Chakraverty

Publications and source records attributed to P Chakraverty.

42 records · Page 3Linked to original sources
PubMed1973

Use of the single radial diffusion technique for influenza antibody surveys.

A survey of antibody to the influenza A/Hong Kong/1/68 (H3N2) and the variant A/England/42/72 (H3N2) was carried out by two methods, haemagglutination-inhibition (HI) and single radial diffusion (SRD). A comparison of the sensitivity of the two tests indicated that the proportion of sera that produced a zone of 2.5 mm or larger in the SRD tests was equivalent to the proportion that gave HI titres of 1: 40 or more. The test was carried out on serum samples collected from various regions of England. The results showed that approximately 70% had antibody to the A/HK/1/68 virus and only 35% had antibody to A/England/42/72. The SRD test was shown to have several practical advantages for seroepidemiological studies.

Antibodies, Viral↗
PubMed1972

Prevalence of antibody to current influenza viruses and effect of vaccination on antibody response.

The extent of antibody to the influenza virus A/Hong Kong/68 (H3N2) after four years of prevalence was investigated in Britain and in the U.S.A. The results indicated a high incidence in both populations. The prevalence of antibody to a variant A/England/42/72 (H3N2) which has been causing epidemics of influenza in the southern hemisphere during the middle months of 1972 was also investigated. The differences reflect the shift in antigenic content of this variant, and although the overall proportion of the sera with antibody at > 1/40 was 37%, some age groups had an incidence of only 20% or less with antibody at this level. A commercial inactivated A/Hong Kong/68 influenza vaccine was given to a group of volunteers in Britain to see how effective it might be in stimulating antibody to the variant A/England/42/72. The antibody responses were better than expected from earlier vaccine studies, and 63% of the vaccinees developed antibody to the A/England/42/72 to levels thought likely to be protective. This suggested that until a vaccine made with the variant A/England/42/72 becomes available the present A/Hong Kong/68 vaccine would be of use to protect those at special risk this winter.

Adolescent↗
PubMed1972

Antigenic relationships between the neuraminidases of influenza B virus.

Antigenic relationships between neuraminidases of influenza B viruses isolated from 1940 to 1968 were studied by neuraminidase-inhibition tests using hyperimmune rabbit antisera. The cross-reactions between the enzymes of influenza B viruses showed that some antigenic drift had occurred but that they are all related. From these results it is concluded that the differences between the neuraminidases of influenza B viruses are not sufficiently clear-cut to allow the viruses to be separated into subgroups.

Animals↗
PubMed1971

Antigenic relationship between influenza B viruses.

The object of this study was to determine whether antigenic groupings exist among influenza B viruses. Altogether, 22 influenza type B strains isolated during the years 1940-68 were examined by reciprocal haemagglutination-inhibition, strain-specific complement-fixation, and serum neutralization tests with sera produced in ferrets and guinea-pigs. It was found that the strain-specific complement-fixation test was superior for separating influenza B viruses into groups whereas the haemagglutination-inhibition and serum neutralization tests were better for demonstrating similarities. The results obtained with these three immunological techniques confirmed that antigenic variation exists among influenza B viruses, although it is not as clearcut as among influenza A viruses.The results were subjected to numerical taxonomic analysis. Dendrograms and minimum-spanning trees were constructed, using methods based on cluster analysis of similarity coefficients. Four main groups of influenza B viruses were established, although they were all interlinked. The results of this study do not justify the separation of influenza B viruses into subtypes similar to those of influenza A viruses.

Antigens↗