[Role of antineuraminidase antibodies in protection against XXXX ].

@entity689 @entity1 @entity1707 @entity778 @entity683 @entity281
For improving the anti- @entity683 vaccination efficacy, the choice of strains carrying up dated @entity689 antigen (NA) and the introduction of the optimal amount of NA antigen in the vaccine are critical. Monoclonal antibodies prepared against the @entity689 N2 of A/Beijing/32/92 showed NA inhibition (NI) and neutralized (Nt) the cells infection by @entity683 virus either at an early stage (group 2 antibodies inhibit virus binding to cells) or at a late stage of infection (group 1 antibodies inhibit virus release). The specificity of the neutralization test is restricted to the homologous variant whereas the NI specificity is much broader. When both group 1 and group 2 antibodies are tested together, their neutralizing activity is significantly increased. The emergence in 1997 of an avian strain H5N1 in @entity1 @entity281 at Hong Kong (Strain A/Hong-Kong/156/97) rose the threat of pandemic. The H5N1 strain carried H5 HA which is not recognized by the @entity1 immune system, but N1 might be related to other N1 antigens belonging to avian, @entity1707 and @entity1 strains. So we 1) characterized the N1 antigen from H5N1 in comparison with other known antigens, 2) we looked for anti N1 (H5N1) antibodies in @entity1 according to the age and the vaccination status, 3) we checked the neutralizing activity of anti N1 antibodies. The N1 antigen (H5N1) appeared closely related to N1 from @entity1707 strains: Sw/31 correlated itself to the @entity778 (1918-19), and more recent @entity1707 isolates from 1982 and 1989. The anti N1 (H5N1) antibodies were present in sera collected from 75+ years old @entity1 and these N1 antibodies were neutralizing H5N1 cells infection. Consequently, 75+ years old @entity1 do not represent a priority group for vaccination in the case of H5N1 pandemic conditions.
