Antigenic and genomic relation between human influenza viruses that circulated in Argentina in the period 1995-1999 and the corresponding vaccine components.
BACKGROUND
The analysis of epidemic influenza virus has been focused on antigenic and genomic characterization of the hemagglutinin (HA) glycoprotein in order to detect new variants for the recommendation of the vaccine strains in each season. Since October 1998, WHO organized a second meeting to evaluate the vaccine formula for the southern hemisphere.


OBJECTIVE
(a) Present the antigenic and genomic characterization of influenza strains obtained from the Argentina surveillance network, (b) compare between strains collected in Argentina and other countries with the vaccine formula strains used in each season.


METHODS
Influenza strains were collected during a 5-year period (1995-1999). Initially, laboratory diagnosis was done by immunofluorescence (IF) assay on clinical samples, followed by viral isolation in Madin-Darby canine kidney (MDCK) cells. The isolates were characterized antigenically by hemagglutination-inhibition (HI) assay with post-infection ferret antisera. The genomic characterization consisted on RT-PCR followed by sequencing of the HA1 portion of the HA gene. The comparison between reference and circulating strains was analyzed by the construction of phylogenetic trees.


RESULTS
The H3N2 circulating strains matched the corresponding vaccine component only in 1999, the first year when a vaccine recommended specifically for the southern hemisphere was used. Besides, H1N1 circulating strains matched the corresponding vaccine component only in 1998. Regarding to influenza B, only in 1995, the circulating strains showed no match to the B vaccine component.


CONCLUSIONS
The results showed the usefulness of an intensified influenza laboratory surveillance to access the correct vaccine and the importance of having the necessary tools to characterize the circulating strains.
Pontoriero
Andrea Verónica
AV
Departamento Virología, INEI-ANLIS Carlos G. Malbrán, Servicio de Virus Respiratorios, Av. Vélez Sarsfield 563, 1281 Buenos Aires, Argentina. aponto@anlis.gov.ar
Baumeister
Elsa Graciela
EG
Campos
Ana María
AM
Savy
Vilma Lidia
VL
Lin
Yi Pu
YP
Hay
Alan
A
D000818:Animals; D000940:Antigenic Variation; D000956:Antigens, Viral / Q000276:immunology*; D001118:Argentina / Q000453:epidemiology; D016679:Genome, Viral; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D009980:Influenza A virus / Q000235:genetics / Q000276:immunology; D009981:Influenza B virus / Q000145:classification / Q000235:genetics / Q000276:immunology; D007252:Influenza Vaccines / Q000235:genetics / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology; D010802:Phylogeny; D014407:Tumor Cells, Cultured; D014765:Viral Vaccines / Q000276:immunology*
D000956:Antigens, Viral; D007252:Influenza Vaccines; D014765:Viral Vaccines