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Human infection from avian-like influenza A (H1N1) viruses in pigs, China.

Yang H, Qiao C, Tang X, Chen Y, Xin X, Chen H - Emerging Infect. Dis. (2012)

Bottom Line: In investigating influenza in an immunodeficient child in China, in December 2010, we found that the influenza virus showed high sequence identity to that of swine.Serologic evidence indicated that viral persistence in pigs was the source of infection.Continued surveillance of pigs and systemic analysis of swine influenza isolates are needed.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Veterinary Biotechnology–Harbin Veterinary Research Institute, Harbin, People’s Republic of China.

ABSTRACT
In investigating influenza in an immunodeficient child in China, in December 2010, we found that the influenza virus showed high sequence identity to that of swine. Serologic evidence indicated that viral persistence in pigs was the source of infection. Continued surveillance of pigs and systemic analysis of swine influenza isolates are needed.

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Related in: MedlinePlus

Multiple alignment of hemagglutinin protein sequences. Epitopes Sa, Sb, Ca1, Ca2, and Cb are indicated. Triangle, Sa; circle, Sb; square, Ca1; hexagon, Ca2; diamond, Cb. Putative glycosylation sites are indicated in blue-lined boxes.
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Figure 2: Multiple alignment of hemagglutinin protein sequences. Epitopes Sa, Sb, Ca1, Ca2, and Cb are indicated. Triangle, Sa; circle, Sb; square, Ca1; hexagon, Ca2; diamond, Cb. Putative glycosylation sites are indicated in blue-lined boxes.

Mentions: The receptor-binding property of the HA protein is a major molecular determinant of host range. The amino acids at sites 190 and 225 of HA are major determinants of the receptor-binding specificity of the A (H1N1) virus, and the mutations E190D and D225E in HA switch the virus receptor-binding specificity from α-2,3–linked sialosides to α-2,6–linked sialosides (6). The Sw/JS/40/11 and JS/1/11 isolates have the amino acids D at site 190 and E at site 225 within the HA protein, which implies that these viruses might preferentially bind to α-2,6–linked sialosides. Potential glycosylation sites (PGSs) also have a major effect on the antigenic and receptor-binding properties of influenza A viruses. Molecular analysis showed that the 2 Jiangsu strains had 5 PGSs in their HA1 proteins, 4 of which were the same as those of the A/Netherlands/386/1986 virus (the cause of the first avian-like SIV infection in a human). Antigenic sites in the H1 HAs, i.e., Sa, Sb, Ca1, Ca2, and Cb, were compared between A/Netherlands/386/1986 and JS/1/11. Amino acid mutations H159N, K238R, and G239E were observed at the Ca2 site; R187G at the Ca1 site; and T202D, N203S, S207T, and A212N at the Sb site. Compared with JS/1/11, the unique mutation D204V, located at the Sb site, which is an antigenic site near the receptor-binding site in influenza virus (7), occurred in the HA1 of Sw/JS/40/11 (Figure 2). No oseltamivir resistance–conferring substitutions (H274Y and N294S) were observed in the NA proteins of the 2 viruses, which suggests that they are sensitive to NA inhibitors (8). The amino acid sequence of the M2 protein of the 2 isolates did not contain the I27T or S31N substitution, characteristic of amantadine resistance in influenza viruses (9,10). The 627K and 701N residues in the PB2 protein contribute to the replication and transmission of avian influenza viruses in mammalian hosts (11–14). Similar to most avian-like A (H1N1) SIVs, both isolates (JS/1/11 and Sw/JS/40/11) had 701N in their PB2 gene.


Human infection from avian-like influenza A (H1N1) viruses in pigs, China.

Yang H, Qiao C, Tang X, Chen Y, Xin X, Chen H - Emerging Infect. Dis. (2012)

Multiple alignment of hemagglutinin protein sequences. Epitopes Sa, Sb, Ca1, Ca2, and Cb are indicated. Triangle, Sa; circle, Sb; square, Ca1; hexagon, Ca2; diamond, Cb. Putative glycosylation sites are indicated in blue-lined boxes.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3376805&req=5

Figure 2: Multiple alignment of hemagglutinin protein sequences. Epitopes Sa, Sb, Ca1, Ca2, and Cb are indicated. Triangle, Sa; circle, Sb; square, Ca1; hexagon, Ca2; diamond, Cb. Putative glycosylation sites are indicated in blue-lined boxes.
Mentions: The receptor-binding property of the HA protein is a major molecular determinant of host range. The amino acids at sites 190 and 225 of HA are major determinants of the receptor-binding specificity of the A (H1N1) virus, and the mutations E190D and D225E in HA switch the virus receptor-binding specificity from α-2,3–linked sialosides to α-2,6–linked sialosides (6). The Sw/JS/40/11 and JS/1/11 isolates have the amino acids D at site 190 and E at site 225 within the HA protein, which implies that these viruses might preferentially bind to α-2,6–linked sialosides. Potential glycosylation sites (PGSs) also have a major effect on the antigenic and receptor-binding properties of influenza A viruses. Molecular analysis showed that the 2 Jiangsu strains had 5 PGSs in their HA1 proteins, 4 of which were the same as those of the A/Netherlands/386/1986 virus (the cause of the first avian-like SIV infection in a human). Antigenic sites in the H1 HAs, i.e., Sa, Sb, Ca1, Ca2, and Cb, were compared between A/Netherlands/386/1986 and JS/1/11. Amino acid mutations H159N, K238R, and G239E were observed at the Ca2 site; R187G at the Ca1 site; and T202D, N203S, S207T, and A212N at the Sb site. Compared with JS/1/11, the unique mutation D204V, located at the Sb site, which is an antigenic site near the receptor-binding site in influenza virus (7), occurred in the HA1 of Sw/JS/40/11 (Figure 2). No oseltamivir resistance–conferring substitutions (H274Y and N294S) were observed in the NA proteins of the 2 viruses, which suggests that they are sensitive to NA inhibitors (8). The amino acid sequence of the M2 protein of the 2 isolates did not contain the I27T or S31N substitution, characteristic of amantadine resistance in influenza viruses (9,10). The 627K and 701N residues in the PB2 protein contribute to the replication and transmission of avian influenza viruses in mammalian hosts (11–14). Similar to most avian-like A (H1N1) SIVs, both isolates (JS/1/11 and Sw/JS/40/11) had 701N in their PB2 gene.

Bottom Line: In investigating influenza in an immunodeficient child in China, in December 2010, we found that the influenza virus showed high sequence identity to that of swine.Serologic evidence indicated that viral persistence in pigs was the source of infection.Continued surveillance of pigs and systemic analysis of swine influenza isolates are needed.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Veterinary Biotechnology–Harbin Veterinary Research Institute, Harbin, People’s Republic of China.

ABSTRACT
In investigating influenza in an immunodeficient child in China, in December 2010, we found that the influenza virus showed high sequence identity to that of swine. Serologic evidence indicated that viral persistence in pigs was the source of infection. Continued surveillance of pigs and systemic analysis of swine influenza isolates are needed.

Show MeSH
Related in: MedlinePlus