title: Antiviral susceptibility profile of influenza A viruses; keep an eye on immunocompromised patients under prolonged treatment.
abstract: There was an increase in severe and fatal influenza cases in Greece during the 2011-2015 post-pandemic period. To investigate causality, we determined neuraminidase (NA) inhibitor susceptibility and resistance-conferring NA and hemagglutinin (HA) mutations in circulating influenza type A viruses during the pandemic (2009-2010) and post-pandemic periods in Greece. One hundred thirty-four influenza A(H1N1)pdm09 and 95 influenza A(H3N2) viruses submitted to the National Influenza Reference Laboratory of Southern Greece were tested for susceptibility to oseltamivir and zanamivir. Antiviral resistance was assessed by neuraminidase sequence analysis, as well as the fluorescence-based 50 % inhibitory concentration (IC50) method. Five influenza A(H1N1)pdm09 viruses (2.2 %) showed significantly reduced inhibition by oseltamivir (average IC50300.60nM vs. 1.19nM) by Gaussian kernel density plot analysis. These viruses were isolated from immunocompromised patients and harbored the H275Y oseltamivir resistance-conferring NA substitution. All A(H1N1)pdm09 viruses were zanamivir-susceptible, and all A(H3N2) viruses were susceptible to both drugs. Oseltamivir-resistant viruses did not form a distinct cluster by phylogenetic analysis. Permissive mutations were detected in immunogenic and non immunogenic NA regions of both oseltamivir- resistant and susceptible viruses in the post-pandemic seasons. Several amino acid substitutions in the HA1 domain of the HA gene of post-pandemic viruses were identified. This study indicated low resistance to NAIs among tested influenza viruses. Antiviral resistance emerged only in immunocompromised patients under long-term oseltamivir treatment. Sequential sample testing in this vulnerable group of patients is recommended to characterise resistance or reinfection and viral evolution.
authors.affiliation: National Influenza Reference Laboratory of Southern Greece, Hellenic Pasteur Institute, 127, Vas. Sofias Ave., 11521, Athens, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Kossyvakis
authors.affiliation: National Influenza Reference Laboratory of Southern Greece, Hellenic Pasteur Institute, 127, Vas. Sofias Ave., 11521, Athens, Greece.|Johns Hopkins University, AAP, Baltimore, MD, USA.
authors.forename: A-F A
authors.initials: AA
authors.lastname: Mentis
authors.affiliation: European Programme for Public Health Microbiology Training (EUPHEM), European Centre for Disease Prevention and Control, Stockholm, Sweden.|Antimicrobial Resistance and Healthcare-associated Infections Laboratory, National School of Public Health, Athens, Greece.|Hellenic Central Public Health Laboratory, Hellenic Centre for Disease Control and Prevention, Athens, Greece.
authors.forename: K
authors.initials: K
authors.lastname: Tryfinopoulou
authors.affiliation: National Influenza Reference Laboratory of Southern Greece, Hellenic Pasteur Institute, 127, Vas. Sofias Ave., 11521, Athens, Greece.
authors.forename: V
authors.initials: V
authors.lastname: Pogka
authors.affiliation: National Influenza Reference Laboratory of Southern Greece, Hellenic Pasteur Institute, 127, Vas. Sofias Ave., 11521, Athens, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Kalliaropoulos
authors.affiliation: 4th Academic Department of Internal Medicine and Infectious Diseases, Attikon University Hospital, University of Athens Medical School, Athens, Greece.
authors.forename: E
authors.initials: E
authors.lastname: Antalis
authors.affiliation: Department of Epidemiological Surveillance and Intervention, Hellenic Centre for Disease Control and Prevention, Athens, Greece.|Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.|Department of Experimental and Health Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain.
authors.forename: T
authors.initials: T
authors.lastname: Lytras
authors.affiliation: National Institute for Public Health and the Environment, Centre for Infectious Disease Control, Bilthoven, Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Meijer
authors.affiliation: 4th Academic Department of Internal Medicine and Infectious Diseases, Attikon University Hospital, University of Athens Medical School, Athens, Greece.
authors.forename: S
authors.initials: S
authors.lastname: Tsiodras
authors.affiliation: Department of Cytopathology, Attikon University Hospital, University of Athens Medical School, Athens, Greece.
authors.forename: P
authors.initials: P
authors.lastname: Karakitsos
authors.affiliation: National Influenza Reference Laboratory of Southern Greece, Hellenic Pasteur Institute, 127, Vas. Sofias Ave., 11521, Athens, Greece. mentis@pasteur.gr.
authors.forename: A F
authors.initials: AF
authors.lastname: Mentis
mesh_terms: D000368:Aged; D000998:Antiviral Agents / Q000494:pharmacology*; D024882:Drug Resistance, Viral; D005260:Female; D005838:Genotype; D006115:Greece; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D016867:Immunocompromised Host; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D053122:Influenza A Virus, H3N2 Subtype / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D007251:Influenza, Human / Q000821:virology*; D020128:Inhibitory Concentration 50; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D020125:Mutation, Missense; D009439:Neuraminidase / Q000235:genetics; D053139:Oseltamivir / Q000494:pharmacology; D014764:Viral Proteins / Q000235:genetics; D053243:Zanamivir / Q000494:pharmacology
chemical_list: D000998:Antiviral Agents; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D014764:Viral Proteins; D053139:Oseltamivir; C487630:NA protein, influenza A virus; D009439:Neuraminidase; D053243:Zanamivir