Antigenic variants with amino acid deletions clarify a neutralizing epitope specific for influenza B virus Victoria group strains

Abstract

To study the neutralizing epitopes of influenza B virus Victoria group strains, two monoclonal antibodies (MAbs) were used to select antigenic variants of the virus. MAbs 10B8 and 8E6 were found to react with B/Victoria group strains in three tests, peroxidase-antiperoxidase staining, haemagglutination inhibition and neutralization tests ; no reactivity with B/Yamagata group strains was observed. Analysis of the deduced amino acid sequences of 10B8-induced variants identified a single amino acid deletion at residue 165 or 170, as well as a single amino acid substitution at residues 164 (Asp Tyr), 165 (Asn Ser or Thr) or 203 (Lys Thr or Asn). A single amino acid substitution at residue 241 (Pro Ser) was observed in 8E6-induced variants. Three-dimensional analysis showed that the epitopes for both MAbs were situated in close proximity to each other. Since B/Yamagata group strains are characterized by amino acid deletions at residues 164-166, the epitope for MAb 10B8 is strictly specific for B/ Victoria group strains.Influenza is one of the most important infectious diseases in both industrial and developing countries. Influenza B virus strains cause epidemics in humans as H1 and H3 subtype strains of influenza A virus. Compared with influenza A virus, influenza B virus is characterized by a low rate of antigenic change ; genetic reassortment, insertion and deletion are responsible for its evolution (Lindstrom et al., 1999 ;McCullers et al., 1999). Influenza B virus strains are divided into two large phylogenic trees : one group is represented by B\Victoria\2\87 and the other is represented by B\ Yamagata\16\88 (Kanegae et al., 1990). Virus strains of the B\Victoria group were dominant all over the world in the 1980s, while the B\Yamagata group strains became dominant in the early 1990s. However, in the mid 1990s, B\Victoria group strains re-emerged in South China. Since the 1996-1997 epidemic season in Japan, two distinctly different antigenic groups of influenza B viruses have been isolated from clinical specimens during the same epidemic season (Nakagawa et al., 1999 ;Nerome et al., 1998). We obtained monoclonal antibodies (MAbs) specific for influenza B virus and used them for peroxidase-antiperoxidase (PAP) staining. When MAbs specific for either the nucleoprotein or the matrix protein were used, both the B\Victoria and B\Yamagata group strains were detected equally well. When MAb 10B8, which is specific for the haemagglutinin (HA) molecule, was used for PAP staining, the two strains were clearly distinguishable (Nakagawa et al., 1999). MAb 10B8 not only reacted with all B\Victoria group strains in PAP staining, but also showed strong activity in haemagglutination inhibition (HI) and neutralization (NT) tests. MAb 8E6 reacted with about 70 % of the B\Victoria group strains isolated during the 1996-1997 season in PAP staining and showed HI and NT test reactivity with 45 %. Neither MAb reacted with the B\Yamagata group strains (Nakagawa et al., 2000).In order to study neutralizing epitopes that are specific for ...

Influence of single amino acid substitutions in the hemagglutinin on the antigenic and receptor-binding properties of influenza virus B/Florida/04/2006 of Yamagata-like evolutionary lineage

“…At the same time, the escape mutant 9A3, in addition to the acquired resistance to the homologous mAb lost the ability to interact with the heterologous mAb 8H3. The analogous phenomenon has been described in the literature [17]. The authors showed that from the eight different escape mutants (V1 -V8) of virus B/Osaka/983/97 of Victorian lineage, selected with mAb 10B8, only two (V3 and V8), which have the amino acid substitution Lys→Thr at position 203 (202 according to the Yamagata numbering and 193 according to the H3 numbering), lost their ability to interact with the heterologous mAb 8E6.…”

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

“…Furthermore, with the recent B/Victoria isolates, other amino acid substitutions were observed in the "tip" of the HA molecule, where B/Victoria strain-specific epitope sites exist (8). Whether these sites affect viral antigenicities is now under investigation.…”

“…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.…”

“…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). Briefly, reverse transcriptase PCR products were sequenced with a DYEnamic ET terminator cycle sequencing kit (Amersham Pharmacia, Piscataway, N.J.) and were analyzed with an ABI Prism 310 automatic sequencer (Perkin Elmer, Foster City, Calif.).…”

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

“…Site B and site A (a protruding loop region) of the HA molecule have been reported to be the highly immunodominant regions of influenza A and B viruses (1,17). We developed monoclonal antibodies (MAbs) 10B8 and 10D7, whose epitopes had been conserved at site B of B/Victoria isolates since the mid-1980s until the 1996/1997 season (7,9). However, the 2002/2003 isolates in Kobe, Japan, were divided into three groups according to their reactivities to 10B8 and 10D7.…”