RESUMO
The vaccine strains for live attenuated influenza vaccines (LAIVs) have cold-adapted, temperature-sensitive, and attenuated phenotypes, which are guaranteed by the presence of specific mutations from the master donor virus in their internal genes. In this study, we used mutant viruses of the pathogenic A/Puerto Rico/8/34 (H1N1) that contained ts-mutations in PB1 (K265N, V591I), PB2 (V478L), and PA (L28P, V341L) genes along and/or in different combinations to evaluate the impact of these mutations in the immune responses. Sequential addition of tested mutations resulted in the stepwise decrease in virus-specific serum and, to a lesser extent, mucosal antibody levels. We demonstrated strong positive correlation between virus attenuation (virus titer in lung) and antibody titers. The ts-mutations in PB1, PB2, and PA genes are mostly involved in the modulation of the humoral immunity, but also have a moderate effect on the cellular adaptive immune response.
Assuntos
Imunidade Celular , Vírus da Influenza A Subtipo H1N1 , Mutação Puntual/imunologia , RNA Polimerase Dependente de RNA , Proteínas Virais , Animais , Modelos Animais de Doenças , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/imunologia , Camundongos , Camundongos Endogâmicos CBA , Infecções por Orthomyxoviridae , RNA Polimerase Dependente de RNA/genética , RNA Polimerase Dependente de RNA/imunologia , Proteínas Virais/genética , Proteínas Virais/imunologiaRESUMO
The cytotoxic T-cell immune response plays an important role in the prevention of influenza infection and reducing of the illness severity. The knowledge about mechanisms of the virus-specific CD8+ T-cell induction in humans is necessary for better understanding of influenza epidemiology and vaccine development. Due to application of new immunological and genetic methods in last years, considerable amount of.data became available in the literature about CD8+ T-cell immune responses to different influenza A viruses. This review summarizes these data. The main attention is paid to (i) heterosubtypic CTL responses to conservative immunodominant sites; (ii) mechanisms of viral escape from the virus-specific CTLs by means of evolutional escape-mutations; (iii) influence of the HLA haplotype on CD8+ T-cell immune responses. The importance of these data for immunology and vaccinology is discussed.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Epitopos de Linfócito T/imunologia , Vírus da Influenza A/imunologia , Influenza Humana/imunologia , Mutação/imunologia , Proteínas Virais/imunologia , Epitopos de Linfócito T/genética , Humanos , Evasão da Resposta Imune/genética , Imunidade Celular/genética , Vírus da Influenza A/genética , Influenza Humana/genética , Proteínas Virais/genéticaRESUMO
Mucosal immunity is one of the most important factors of human anti-influenza defense. The data about local immune responses in influenza A (H3N2) patients and in persons vaccinated within 2000-2009 with different seasonal LAIVs, A (H1N1)pdm2009 LAIV, and A (H5N2) LAIV are discussed. The influenza infection resulted in the larger quantities of local IgA and IgG conversions than seasonal LAIV vaccination. 56% of young (18-21 y.o.) persons had high titers (> or = 1:64) of IgA to A (H1N1)pdm2009 virus before its circulation. 19% of persons had anti A (H5N2) IgA before vaccination. Two-fold vaccination with A (H1N1) pdm2009 and A (H5N2) LAIVs resulted in local antibody conversions in 54% and 27% of volunteers, respectively. Both these vaccines increased local IgA avidity. The number of antibody conversions after vaccination with seasonal LAIVs was in inverse dependence on their titers before vaccination. These results make it possible to conclude that the intensity of local antibody immune response to any LAIV depends on the state of local immunological memory, particularly on the presence of the crossreactive antibody-secreting B cells.
