Corrigendum: Identification of Rare PB2-D701N Mutation from a Patient with Severe Influenza: Contribution of the PB2-D701N Mutation to the Pathogenicity of Human Influenza.

[This corrects the article on p. 575 in vol. 8, PMID: 28421062.].

Identification of Rare PB2-D701N Mutation from a Patient with Severe Influenza: Contribution of the PB2-D701N Mutation to the Pathogenicity of Human Influenza.

Several amino acid changes have been previously implicated in adaptation of avian influenza viruses to human hosts, among them the D701N change in the PB2 polymerase subunit that also is the main determinant of avian virus pathogenesis in animal models. However, previous studies using recombinant viruses did not provide conclusive information of the contribution of this PB2 residue to pathogenicity in human influenza virus strains. We identified this mutation in an A(H1N1)pdm09-like human influenza virus isolated from an infected patient with pneumonia and acute respiratory failure, admitted to the intensive care unit. An exhaustive search has revealed PB2-D701 as a highly conserved position in all available H1N1 human virus sequences in NCBI database, showing a very low prevalence of PB2-D701N change. Presence of PB2-701N amino acid correlates with severe or fatal outcome in those scarce cases with known disease outcome of the infection. In these patients, the residue PB2-701N may contribute to pathogenicity as it was previously reported in humans infected with avian viruses. This study helps to clarify a debate that has arisen regarding the role of PB2-D701N in human influenza virus pathogenicity.

Seasonal Influenza A H1N1pdm09 Virus and Severe Outcomes: A Reason for Broader Vaccination in Non-Elderly, At-Risk People.

BACKGROUND: Recent pandemics of influenza A H1N1pdm09 virus have caused severe illness, especially in young people. Very few studies on influenza A H1N1pdm09 in post-pandemic periods exist, and there is no information on the severity of both seasonal influenza A(H1N1) and A(H3N2) from the same season, adjusting for potential confounders, including vaccine. METHODS AND RESULTS: We performed a retrospective observational study of adults hospitalized during the 2014 season with influenza A(H1N1) or A(H3N2). All patients underwent the same diagnostic and therapeutic protocol in a single hospital, including early Oseltamivir therapy. We included 234 patients: 146 (62.4%) influenza A(H1N1) and 88 (37.6%) A(H3N2). A(H1N1) patients were younger (p<0.01), developed more pneumonia (p<0.01), respiratory complications (p = 0.015), ARDS (p = 0.047), and septic shock (p = 0.049), were more frequently admitted to the ICU (p = 0.022), required IMV (p = 0.049), and were less frequently vaccinated (p = 0.008). After adjusting for age, comorbidities, time from onset of illness, and vaccine status, influenza A(H1N1) (OR, 2.525), coinfection (OR, 2.821), and no vaccination (OR, 3.086) were independent risk factors for severe disease. CONCLUSIONS: Hospitalized patients with influenza A(H1N1) were more than twice as likely to have severe influenza. They were younger and most had not received the vaccine. Our findings suggest that seasonal influenza A(H1N1) maintains some features of pandemic viruses, and recommend wider use of vaccination in younger adult high-risk patients.

Comparison of epidemiology and clinical characteristics of infections by human parechovirus vs. those by enterovirus during the first month of life.

UNLABELLED: Human parechoviruses (HPeV) have been recently recognized as important viral agents in paediatric infections. The aims of this study were to investigate the HPeV infection prevalence in infants <1 month in Spain and, secondly, to analyse the clinical and epidemiological characteristics of the infected patients compared with those infected by enterovirus (EV). Infants <1 month with neurological or systemic symptoms were included in a multicentre prospective study. EV and HPeV detection by RT-PCR and genotyping were performed in cerebrospinal fluids (CSF), sera or throat swabs. Out of the total of 84 infants studied during 2013, 32 were EV positive (38 %) and 9 HPeV positive (11 %). HPeV-3 was identified in eight cases and HPeV-5 in one. Mean age of HPeV-positive patients was 18 days. Diagnoses were fever without source (FWS) (67 %), clinical sepsis (22 %) and encephalitis (11 %). Leukocytes in blood and CSF were normal. Pleocytosis (p = 0.03) and meningitis (p = 0.001) were significantly more frequent in patients with EV infections than with HPeV. CONCLUSIONS: Although HPeV-3 infections were detected less frequently than EV, they still account for approximately 10 % of the cases analysed in infants younger than 1 month. HPeV-3 was mainly associated with FWS and without leukocytosis and pleocytosis in CSF. In these cases, HPeV screening is desirable to identify the aetiologic agent and prevent unnecessary treatment and prolonged hospitalization.