A (H1N1) pdm09 HA D222 variants associated with severity and mortality in patients during a second wave in Mexico.
BACKGROUND
Pandemic type A (H1N1) influenza arose in early 2009, probably in Mexico and the United States, and reappeared in North America in September for seven more months. An amino acid substitution in the hemagglutinin (HA), D222G, has been reported in a significant proportion of patients with a severe and fatal outcome. We studied the prevalence of HA222 substitutions in patients in Mexico during the second wave and its association with clinical outcome and pathogenicity in a mouse model.


METHODS
The nucleotide sequences of hemagglutinin (HA) from viruses collected from 77 patients were determined including 50 severe and fatal cases and 27 ambulatory cases. Deep sequencing was done on 5 samples from severe or fatal cases in order to determine the quasispecies proportion. Weight loss and mortality due to infection with cultured influenza viruses were analyzed in a mouse model.


RESULTS
Viruses from 14 out of 50 hospitalized patients (28%) had a non aspartic acid residue at the HA 222 position (nD222), while all 27 ambulatory patients had D222 (p=0.0014). G222 was detected as sole species or in coexistence with N222 and D222 in 12 patients with severe disease including 8 who died. N222 in coexistence with D222 was detected in 1 patient who died and co-occurrence of A222 and V222, together with D222, was detected in another patient who died. The patients with a nD222 residue had higher mortality (71.4%), compared to the group with only D222 (22.2%, p=0.0008). Four of the 14 viruses from hospitalized patients were cultured and intranasally infected into mice. Two viruses with G222 were lethal while a third virus, with G222, caused only mild illness in mice similar to the fourth virus that contained D222.


CONCLUSIONS
We confirm the elevated incidence of HA222 (H1N1)pdm09 variants in severe disease and mortality. Both clinical and mouse infection data support the idea that nD222 mutations contribute to increased severity of disease but additional determinants in disease outcome may be present.
Instituto Nacional de Enfermedades Respiratorias, Mexico City, Mexico.
Joel A
JA
Vazquez-Perez
Pavel
P
Isa
Darwyn
D
Kobasa
Christopher E
CE
Ormsby
Jose E
JE
Ramírez-Gonzalez
Damaris P
DP
Romero-Rodríguez
Charlene
C
Ranadheera
Yan
Y
Li
Nathalie
N
Bastien
Carissa
C
Embury-Hyatt
Elizabeth
E
González-Duran
Gisela
G
Barrera-Badillo
Yuria
Y
Ablanedo-Terrazas
Edgar E
EE
Sevilla-Reyes
Marina
M
Escalera-Zamudio
Ana G
AG
Cobián-Güemes
Irma
I
Lopez
Joanna
J
Ortiz-Alcántara
Celia
C
Alpuche-Aranda
Jose R
JR
Perez-Padilla
Gustavo
G
Reyes-Terán
D000328:Adult; D000818:Animals; D001483:Base Sequence; D001835:Body Weight; D004195:Disease Models, Animal; D005260:Female; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D006651:Histocytochemistry; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D007251:Influenza, Human / Q000453:epidemiology / Q000401:mortality* / Q000473:pathology* / Q000821:virology; D008168:Lung / Q000473:pathology; D008297:Male; D008800:Mexico / Q000453:epidemiology; D051379:Mice; D008875:Middle Aged; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009976:Orthomyxoviridae Infections / Q000473:pathology / Q000821:virology; D012367:RNA, Viral / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012720:Severity of Illness Index; D016019:Survival Analysis; D037521:Virulence Factors / Q000235:genetics*
D019267:Hemagglutinin Glycoproteins, Influenza Virus; D012367:RNA, Viral; D037521:Virulence Factors