Neutralizing epitopes specific for influenza B virus Yamagata group strains are in the ‘loop’

Discovery of the Neutralizing Epitope Common to Influenza B Virus Victoria Group Isolates in Japan

“…These residues were suggested to form the additional antigenic sites such as site E and affect site A (17). In contrast, only two immunodominant antigenic sites, site A and site B, have been discussed with regard to influenza B virus (1,9,10). It is noteworthy that the 9B2 epitope did not belong to either of the above antigenic sites.…”

“…Escape mutants were induced by incubating virus with 9B2, by a modification of the method previously described (1,4,10). The nucleotide sequences of the escape mutants were analyzed as described previously (8)(9)(10)(11)(12).…”

Influenza B Virus Victoria Group with a New Glycosylation Site Was Epidemic in Japan in the 2002-2003 Season

“…NET strains, which represented less than 30% of the virus strains in the 1996-1997 season (7) caused the strains not to react to MAb 5H4 in HI tests and in neutralization tests (9). K strains became predominant in a year, and after the 1999-2000 season all of the isolates in our area were found to be K strains (9,11). These phenomena suggest the theory that the new antigenic variants emerge because they have a selective advantage due to the immunity present in the population towards old strains (2).…”

“…Antigenic variants often show only a one-point nucleotide mutation, which results in one amino acid substitution (1,8,11). In this case, NET strains gained an N-linked glycosylation site in the vicinity of the epitope site of 8E6.…”

“…However, B/Victoria strains reemerged in South China in 1994, and in Japan they were epidemic in the 1996-1997 season for the first time after the reemergence. After the 1997-1998 season, B/Yamagata strains were predominant in Kobe City (9,11) (13). Direct sequencing of viral nucleotides was performed as described previously (7)(8)(9).…”