Research Article: Molecular features of influenza A (H1N1)pdm09 prevalent in Mexico during winter seasons 2012-2014

Date Published: July 10, 2017

Publisher: Public Library of Science

Author(s): Rocío Arellano-Llamas, Luis Alfaro-Ruiz, Cristian Arriaga Canon, Ivan Imaz Rosshandler, Alfredo Cruz-Lagunas, Joaquín Zúñiga, Rosa Rebollar Vega, Christopher W. Wong, Sebastian Maurer-Stroh, Sandra Romero Córdoba, Edison T. Liu, Alfredo Hidalgo-Miranda, Joel A. Vázquez-Pérez, Juan C. de la Torre.


Since the emergence of the pandemic H1N1pdm09 virus in Mexico and California, biannual increases in the number of cases have been detected in Mexico. As observed in previous seasons, pandemic A/H1N1 09 virus was detected in severe cases during the 2011–2012 winter season and finally, during the 2013–2014 winter season it became the most prevalent influenza virus. Molecular and phylogenetic analyses of the whole viral genome are necessary to determine the antigenic and pathogenic characteristics of influenza viruses that cause severe outcomes of the disease. In this paper, we analyzed the evolution, antigenic and genetic drift of Mexican isolates from 2009, at the beginning of the pandemic, to 2014. We found a clear variation of the virus in Mexico from the 2011–2014 season due to different markers and in accordance with previous reports. In this study, we identified 13 novel substitutions with important biological effects, including virulence, T cell epitope presented by MHC and host specificity shift and some others substitutions might have more than one biological function. The systematic monitoring of mutations on whole genome of influenza A pH1N1 (2009) virus circulating at INER in Mexico City might provide valuable information to predict the emergence of new pathogenic influenza virus

Partial Text

Since the emergence of the pandemic H1N1pdm09 virus in Mexico and California, biannual increases in the number of cases have been detected in Mexico [1, 2]

Clinical and demographic characteristics of the studied individuals are summarized in Table 1. The mean age of the patients was 45.4 ± 20.8 years and 76.4% of these individuals were male. The mean BMI (kg/m2) was 29.2, and 23.5% required mechanical ventilation for 15.2 (mean) days. Patients had 22 days of hospitalization stay, 17.6% of them had co-morbidities such as asthma and chronic obstructive pulmonary disease (COPD), and 5.8% of these patients died. Patients who required mechanical ventilation displayed a Kirby index (PaO2/FiO2) (mean: 104.7). The main signs and symptoms at the start of the illness included fever, myalgia, cough, and headaches, while chest pain, dyspnea, and cyanosis occurred after the third day. Critically ill patients received oseltamivir (150 mg/day) during the period while they were under mechanical ventilation while non-critically ill patients received 150mg/day of oseltamivir for 5 days.

Influenza A viruses cause acute respiratory tract infections and represent a significant public health threat [18]. The outbreak strain of swine-origin influenza A/H1N1 virus infection in 2009 is still circulating during the winter season in many countries, and may cause severe pulmonary illness in susceptible individuals [4, 19]. Therefore continuous analysis of the entire genome of these viruses will provide comprehensive information of its molecular evolution in order to maintain effective prevention measures for public health. It has been extensively demonstrated that pandemic A/H1N1 influenza virus contains a mixture of segments, including HA, NP, PB1, PB2, PA and NS from a triple reassortant virus isolated in north America and segments NA and M from the Eurasian swine influenza virus [20, 21].




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