ABSTRACT
The activity and circulation of influenza viruses in Argentina was studied during 2012 as part of the Argentinean Surveillance for Influenza and other Respiratory Viruses, in the context of Global Influenza Surveillance. The antigenicity and molecular characteristics of haemagglutinins (HA) of circulating influenza A and B viruses were analysed to assess the emergence of virus variants. Susceptibility to oseltamivir and zanamivir was evaluated by enzymatic assay and results were backed-up by sequencing of the neuraminidase (NA) genes. During the 2012 season, influenza virus circulation in Argentina was detected from weeks 24 to 51. The HA sequences of the studied A(H1N1)pdm09 subtype viruses segregated in a different genetic group compared to those identified during the 2009 pandemic, although they were still closely related antigenically to the vaccine virus A/California/07/2009. The HA sequences of the A(H3N2) viruses analysed fell into the A/Victoria/208/2009 clade, genetic group 3C. A mixed circulation of virus variants belonging to B/Victoria and B/Yamagata lineages was detected, with B/Victoria being dominant. All viruses tested were sensitive to oseltamivir and zanamivir except one. This isolate, an A(H1N1)pdm09 virus possessing the substitution NA-N295S, showed highly reduced inhibition by oseltamivir and reduced inhibition by zanamivir. Virological and epidemiological surveillance remains critical for detection of evolving influenza viruses.
Subject(s)
Antiviral Agents/pharmacology , Drug Resistance, Viral , Influenza A virus/drug effects , Influenza B virus/drug effects , Influenza, Human/epidemiology , Population Surveillance , Argentina/epidemiology , Hemagglutinins/genetics , Hemagglutinins/metabolism , Humans , Influenza A virus/genetics , Influenza A virus/immunology , Influenza A virus/physiology , Influenza B virus/genetics , Influenza B virus/immunology , Influenza B virus/physiology , Influenza, Human/virology , Neuraminidase/genetics , Neuraminidase/metabolism , Viral Proteins/genetics , Viral Proteins/metabolismABSTRACT
BACKGROUND: During pregnancy, immunological and hormonal alterations place women at increased risk for influenza-related severe illnesses including hospitalization and death. Although A(H1N1) pdm09 infection resulted in increased disease severity in pregnant women, the precise mechanisms responsible for this risk have yet to be established. OBJECTIVES: The present study was aimed to investigate the role of host chemokines and cytokine profiles in A(H1N1) pdm09 infection regarding disease severity in pregnant women. STUDY DESIGN: This retrospective survey examined 41 pregnant women with confirmed A(H1N1) pdm09 infection. Of them, 12 died (D), 29 survived (S), and 17 remained uninfected and served as controls (C). Antiviral response was evaluated for IFN-ß expression and gene expression profiles of cytokines (TNF-α, IL-6, IL-12, TGF-ß) and chemokines (IL-8, RANTES, MCP-1, IP-10), and the viral Matrix (M1) gene was quantified and normalized using the housekeeping gene product ß-actin mRNA. RESULTS: Higher IL-8 and TNF-α mRNA expression were found in D and S compared with C, while IL-6 showed higher expression in D. Interestingly, these results were associated with a decrease in the anti-inflammatory response of TGF-ß mRNA and IFN-ß. These alterations would lead to an imbalance in the immune response of those patients. CONCLUSIONS: Pregnancy-related reductions in IFN-ß and TGF-ß expression levels and elevated levels of pro-inflammatory cytokines could explain the increased severity of infection and death of pregnant women. These findings may help improve the understanding of the high susceptibility and disease severity to influenza virus infection during pregnancy.
