Influenza vaccination in elderly residents in nursing homes: immune response to trivalent and monovalent inactivated influenza virus vaccine in the season 1986-87.

Immune responses to trivalent inactivated whole virus and monovalent subunit influenza vaccines, used in the season 1986-87, were analyzed in elderly residents in nursing homes. Higher levels of induced antibody were found in the group receiving two doses of trivalent vaccine. This suggests that high risk aged patients should receive a booster dose of vaccine annually. The antibody response to administration of supplemental vaccination, using monovalent subunit preparation, did not reach the high level of antibodies found following trivalent influenza vaccine.

Surveillance of influenza A and B viruses in Italy between 1984 and 1987.

Antigenically heterogeneous strains and new variants of influenza A viruses, both A (H3N2) and (H1N1) subtypes, as well as influenza B strains were detected in Italy in a period, between 1984-1987, characterized by a moderate degree of influenza activity. Each year the evaluation, by SRH technique, of antibodies, in the population, to currently circulating viruses, has confirmed the extent of infection and often the prevalent virus.

Comparative electrophoretic study of polypeptides of influenza A/H3N2 viruses isolated in circumscribed geographical areas.

Two distinct groups of influenza A/H3N2 viruses, closely related to A/Bangkok/1/79 and to A/Belgium/2/81, have been chosen from viruses isolated in Italy during 1981 to 1983 with the aim of analysing the biochemical composition of their polypeptides. The strains of each group have shown differences in electrophoretic migration rates in one or more proteins in comparison to the prototype viruses. Polypeptide mobility variations among isolates from circumscribed geographical areas and from single outbreaks have also been observed. In particular, there was a high degree of variability in the NS1 protein. The detection of biochemical differences among identical antigenic variants, probably the result of point mutations in polypeptide sequences or of genetic reassortment among different co-circulating human viruses, is a further expression of the peculiar ability of the influenza A virus to exhibit variation in internal proteins during its circulation.

Antigenic and biochemical analysis of influenza "A" H3N2 viruses isolated from pigs.

Four influenza A-H3N2 viruses isolated in pigs from different herds in Central Italy in the period 1981/82 have been antigenically and biochemically analysed. Three of them A/Sw/Italy/2/81, A/Sw/Italy/7/81, A/Sw/Italy/8/82 were found to be serologically related to A/Bangkok/1/79 (H3N2). These three viruses were shown to have an identical electrophoretic pattern, as regards virus induced polypeptides and were clearly distinguishable from the virus A/Sw/Italy/6/81 which was antigenically related to A/England/42/72 (H3N2) and A/Sw/Taiwan/7310/70 as shown by specific monoclonal and polyclonal antisera. The observed biochemical variations underline the importance of the changes occurring by genetic reassortments or mutations in human influenza viruses, during their maintenance in pigs.

Detection of antibodies to strain-specific and cross-reactive antigenic determinants on the haemagglutinin of influenza viruses A/Texas/1/77 and A/Bangkok/1/79 in human sera. Brief report.

The antibody response to antigenic determinants on the haemagglutinin molecule of A/Texas/77 and A/Bangkok/79 strains was analysed by SRH of virus-absorbed sera, in human sera collected from persons of different ages following natural infection or immunization. The results have shown, as expected, low and high frequencies of strain-specific antibodies in sera of adults and young children respectively. However, in the latter group antibodies to cross-reactive antigens were also detected.

Comparison of haemagglutination-inhibition and single radial haemolysis techniques for detecting antibodies to influenza A and B viruses.

The sensitivities of haemagglutination-inhibition (HI) and single radial haemolysis (SRH) techniques in detecting antibodies against influenza A/Bangkok/1/79, A/Brazil/11/78, B/Singapore/222/79, B/Hong Kong/5/72 strains, in human sera were compared. For antibodies to influenza B viruses the HI tests employing ether-treated antigens were also evaluated. The SRH technique appears to be more sensitive for detecting protective titres of antibodies against influenza B strains and influenza A/Brazil/11/78.

The detection of serum antibody response to type-B influenza virus in vaccinated individuals by enzyme linked immunosorbent assay.

The sensibility of the Immunoenzymatic ELISA test for the evaluation of antibody response in individuals vaccinated with inactivated Influenza vaccine was evaluated in comparison with the results obtained by the Haemagglutination inhibition test using type B Influenza virus as antigen. The rate of seroconversion obtained with the two methods versus each class of HAI titre or each interval of OD values of the prevaccine sera showed similar features. In 23% of the cases, however, sero-conversion was observed only by the ELISA test, in 5.4% of the cases only by the HAI test. It is to be assessed whether the serological response revealed by the ELISA test is fully correlated with protection against the disease.

[Antibody response to trivalent anti-influenza vaccination (inactivated virus) A/Texas/1/77 H3N2), A/URSS/90/77 (H1N1), B/Hong Kong/8/73]. / Risposta anticorpale alla vaccinazione anti-influenzale trivalente (A virus inattivato) A/Texas/1/77 (H3N2), A/URSS/90/77 (H1N1), B/Hong Kong/8/73.

Seventy-five young recruits received an intramuscular dose of anti-influenza virus vaccine containing 300 U.I. of A/Texas/1/77 (H3N2), A/URSS/90/77 (H1N1), B/Hong Kong/8/73 strains. Antibody responses were detected by HI and SRH tests: immunogenicity of the preparation was different for the individual vaccine strain in spite of the similar amount of antigenic content, and the immunity conferred by vaccine strains did not significantly extend to new influenza virus strains which prevailed in 1979/80 winter season with the exception for A/Brazil/11/78 (H1N1).

[Antibody response to an anti-influenza vaccine of inactivated whole virus, titrated in micrograms, used in the 1980/81 season]. / Risposta anticorpale al vaccino anti-influenzale A virus intero inattivato, titolato in microgrammi, in uso nella stagione 1980/81.

Antibody response of 68 healthy young-adult volunteers to A/Bangkok/1/79 (H3N2), A/Brazil/11/78 (H1N1), B/Singapore/222/79 trivalent anti-influenza virus vaccine was studied by haemagglutination inhibition and single radial haemolysis techniques. The results of this study indicate that immunogenicity of the individual components of the vaccine (10 micrograms each) varied significantly, the highest frequence of antibody response occurring for A/Brazil influenza virus strain and the lowest for B/Singapore.

Enzyme-linked immunosorbent assay for the detection of antibodies to type-B influenza virus.

The Enzyme-Linked Immunosorbent assay (ELISA) has been applied to the detection of antibodies to type B influenza virus. The specificity, the sensitivity and the reproducibility of the indirect method has been evaluated. The Haemagglutination inhibition assay (HAI) was used as reference system. The results obtained at a single serum dilution show good correlation between ELISA and HAI test (r = 0.70). Reproducibility is satisfactory. Our results seem to show a better sensitivity of the ELISA test as compared to the HAI test. This feature may be useful for certain applications such as the detection of antibody responses after vaccination. The need of accurate standardization in carrying out the test is pointed out.

[Serological studies of influenza viruses in a sample of the population of Rome]. / Indagine sierologica per i virus influenzali in un campione di popolazione romana.

Haemagglutination inhibiting antibodies (H.I.A.) to influenza viruses A/Victoria/3/75, A/Victoria/112/76, B/Hong Kong/8/73 and A/New Jersey/8/76 were titrated in 1110 serum specimens collected in Rome in the period between March-May 1977 and obtained from subjects 0-60 years old. The H.I.A. protective level (greater than or equal to 1 : 40) found in 21.7% of the sera against A/Victoria/3/75 is such that it does not avoid a possible diffusion of this strain in the successive epidemic season. Moreover this finding suggests that there will be probably no antigenic change (4) in the same period. The age group 0-20 showed the higher titer H.I.A. Low protective levels were found against the virus A/Victoria/112/76 and B/Hong Kong/8/73, while the H.I.A. to virus A/New Jersey/8/76 showed a percentage of protective level increasing with the age.