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Table 5 Dynamics of HA and NA glycosylation for pH1N1 viruses isolated from MENA region during 2009–2017. In total, glycosylation patterns of 512 HA and 343 NA sequences of pH1N1 virus were analyzed. Numbers between brackets represent the percentage of sequences expressing glycosylation sequon in corresponding year while conserved glycosylation sites are indicated in bold

From: Epidemiological and genetic characterization of pH1N1 and H3N2 influenza viruses circulated in MENA region during 2009–2017

Localization of potential glycosylation sequons in HA and NA of pH1N1 viruses

HA

  

Amino acid position

Year

Number of sequences analyzed

Stem

Head

Stem

2009

132

28

40

104

 

304

 

498

557

2010

68

28

40

104

 

304

 

498

557

2011

36

28

40

104

179 (2%)

304

 

498

557

2012

27

28

40

104

 

304

 

498

557

2013

33

28

40

104

 

304

489* (18%)

498

557

2014

25

28

40

104

 

304

 

498

557

2015

157

28

40

104

179 (85%)

304

 

498

557

2016

60

28

40

104

179 (99%)

304

489* (2%)

498

557

NA

Year

Number of sequences analyzed

Amino acid position

2009

97

  

44 (11%)

50

58

63

68

88

146

235

386

2010

42

 

42 (36%)

 

50

58

63

68

88

146

235

386

2011

36

 

42 (100%)

 

50

58

63

68

88

146

235

386*

2012

29

28 (7%)

42 (100%)

 

50

58

63

68

88

146

235

386

2013

32

 

42 (100%)

 

50

58

63

68

88

146

235

386

2014

25

 

42 (100%)

 

50

58

63

68

88

146

235

386

2015

79

 

42 (100%)

 

50

58

63

68

88

146

235

386

2016

3

 

42 (100%)

 

50

58

63

68

88

146

235

 
  1. HA Glycosylation: glycosylation site, N489, was detected in sequences isolated from Iran. Glycosylation sequons at N28, N104, N498 and N557 were lost from viruses isolate from Iran at different time periods. In 2015, for example, N28 and N557 sequons were missing from 1.5 and 5% of HA sequences, respectively. NA Glycosylation: N386 glycosylation sequon was missing from one sequence in 2011, however, during following years more NA sequences were found to lack 386 glycosylation (31% of sequences in 2012; 80% in 2014; 77% in 2015) before disappearing completely from NA sequences in 2016