Surveillance of antiviral resistance markers in Argentina: detection of E119V neuraminidase mutation in a post-treatment immunocompromised patient

Although vaccines are the best means of protection against influenza, neuraminidase inhibitors are currently the main antiviral treatment available to control severe influenza cases. One of the most frequent substitutions in the neuraminidase (NA) protein of influenza A(H3N2) viruses during or soon after oseltamivir administration is E119V mutation. We describe the emergence of a mixed viral population with the E119E/V mutation in the NA protein sequence in a post-treatment influenza sample collected from an immunocompromised patient in Argentina. This substitution was identified by a real-time reverse transcriptase polymerase chain reaction (RT-PCR) protocol and was confirmed by direct Sanger sequencing of the original sample. In 2014, out of 1140 influenza samples received at the National Influenza Centre, 888 samples (78%) were A(H3N2) strains, 244 (21.3%) were type B strains, and 8 (0.7%) were A(H1N1)pdm09 strains. Out of 888 A(H3N2) samples, 842 were tested for the E119V substitution by quantitative RT-PCR: 841 A(H3N2) samples had the wild-type E119 genotype and in one sample, a mixture of viral E119/ V119 subpopulations was detected. Influenza virus surveillance and antiviral resistance studies can lead to better decisions in health policies and help in medical treatment planning, especially for severe cases and immunocompromised patients.Fil: Pontoriero, Andrea. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; ArgentinaFil: Avaro, Martín. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; ArgentinaFil: Benedetti, Estefania. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; ArgentinaFil: Russo, Mara Laura. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Czech, Andrea. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; ArgentinaFil: Periolo, Natalia. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Campos, Ana. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; ArgentinaFil: Zamora, Ana. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; ArgentinaFil: Baumeister, Elsa. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentin

Epidemiological description, case-fatality rate, and trends of Hantavirus Pulmonary Syndrome: 9 years of surveillance in Argentina

Hantavirus pulmonary syndrome (HPS) is an endemic disease in Argentina, one of the most affected countries in the Americas. Andes virus (ANDV) is the main Orthohantavirus species causing HPS in Argentina. In this study, the geographical distribution, clinical presentation, and epidemiological features of HPS from all endemic regions of Argentina were analyzed. We focused on the clinical and epidemiological data from 533 HPS cases confirmed during the period 2009 to 2017 by the National Reference Laboratory for Hantavirus. A case-fatality rate of 21.4% was registered, and most of the cases presented a severe clinical picture requiring intensive care treatment (84%). Since HPS first detection in 1995 the case-fatality rate showed a general trend towards a decrease. After more than 22 years of experience in HPS diagnosis and surveillance, we discuss some possible factors implicated in this tendency. This clinical and epidemiological analysis gives a global perspective, being useful to detect trends and patterns, to update preventive actions at a national level, and evaluate their impact on public health.Fil: Alonso, Daniel Oscar. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; ArgentinaFil: Iglesias, Ayelén Aluminé. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coelho, Rocío María. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; ArgentinaFil: Periolo, Natalia. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bruno, Agostina. Hospital San Vicente de Paul; ArgentinaFil: Córdoba, Maria Teresa. Hospital San Vicente de Paul; ArgentinaFil: Filomarino, Noemi. Hospital Señor Del Milagro; ArgentinaFil: Quipildor, Marcelo. Hospital San Vicente de Paul; ArgentinaFil: Biondo, Emiliano. Ministerio de Salud de la Provincia de Chubut; ArgentinaFil: Fortunato, Eduardo. Provincia de Buenos Aires. Ministerio de Salud; ArgentinaFil: Bellomo, Carla María. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; ArgentinaFil: Martínez, Valeria Paula. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; Argentin

Características clínicas y evolución a largo plazo de una serie de pacientes con sprue refractario diagnosticados en una sola institución

Background: Refractory sprue (RS) is a rare and severe celiac-like enteropathy not responding to a strict gluten-free diet. Although prognosis is generally poor, little is known about the long-term outcome of patients. Aim: to report baseline characteristics and long-term outcome of a series of patients diagnosed and treated in a single institution. Materials: We report a retrospective cohort of 25 consecutive patients (15 females; mean age 46 yr; range 28-71) diagnosed with RS based on the presence of a non-responsive celiac-like enteropathy. All patients were intensively treated with a gluten-free diet, steroids, nutritional support and immunosupression. Results: Clinical and biological characteristics of patients suggest that, at least, 24 patients had clear evidences of celiac disease. HLA DQ2/DQ8 genes were present in all the 24 patients typed and autoimmune enteropathy was excluded in all. According to the genotyping, 12 patients had a polyclonal lymphocyte population (RS type I) and 13 exhibited monoclonal TCR-γ gene rearrangements (RS type II). Sixteen patients had evidence of ulcerative jejunitis (UJ) (7 in RS type I and 9 in type II). Overall median follow-up time after diagnosis of RS was 29 mo/patient (range 7 to 204) (45 mo for type I and 24 mo for type II). Overall mortality was 48% (12 patients), 6 in each type. Eight patients with UJ (50%), 3 with lymphoma (two T-cell and one B-cell type) and 4 (44%) without ulcers died during follow-up. The causes of death were sepsis in the context of a progressive deterioration but without overt malignancies (n=5), vascular causes (n=3) and severe malnutrition (n=1). Three- and 5-yr survival rate after diagnosis of RS for the overall population was 60% and 56%. There was no differences between type I (67%, 58%) and type II RS patients (54% for both periods). Patients with UJ had lower but non-significant 3- and 5-yr survival rates (56% and 50%, respectively) compared with patients without ulcers (78% and 66%). Survivors had a favorable outcome. While 11 patients persists asymptomatic, two other cases still have mild diarrhea and one low body weight. Conclusions: We confirm that RS is a severe celiac disease-related disorder with very high mortality. Diagnosis of overt lymphoma (12%) in our long-term follow-up was not as frequent as was reported by other groups. A proportion of patients persist in good health for a long time irrespective of the nature of the IEL infiltration or the presence of UJ.Fil: Mauriño, Eduardo. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Niveloni, Sonia Isabel. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Cherñavsky, Alejandra Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Inmunogenética; ArgentinaFil: Sugai, Emilia. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Vázquez, Horacio. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Pedreira, Silvia. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Periolo, Natalia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Inmunogenética; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mazure, Roberto. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Smecuol, Edgardo. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Moreno, Maria L.. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Litwin, Néstor. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Nachman, Fabio. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Kogan, Zulema. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Bai, Julio C.. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; Argentin

Delayed viral clearance despite high number of activated T cells during the acute phase in Argentinean patients with hantavirus pulmonary syndrome

Background: The hallmarks of HPS are increase of vascular permeability and endothelial dysfunction. Although an exacerbated immune response is thought to be implicated in pathogenesis, clear evidence is still elusive. As orthohantaviruses are not cytopathic CD8+ T cells are believed to be the central players involved in pathogenesis. Methods: Serum and blood samples from Argentinean HPS patients were collected from 2014 to 2019. Routine white blood cell analyses, quantification and characterization of T-cell phenotypic profile, viral load, neutralizing antibody response and quantification of inflammatory mediators were performed. Findings: High numbers of activated CD4+ and CD8+ T cells were found in all HPS cases independently of disease severity. We found increased levels of some proinflammatory mediators during the acute phase of illness. Nonetheless, viral RNA remained high, showing a delay in clearance from blood up to late convalescence, when titers of neutralizing antibodies reached a high level. Interpretation: The high activated phenotypic profile of T cells seems to be unable to resolve infection during the acute and early convalescent phases, and it was not associated with the severity of the disease. Thus, at least part of the activated T cells could be induced by the dysregulated inflammatory response in an unspecific manner. Viral clearance seems to have been more related to high titers of neutralizing antibodies than to the T-cell response. Funding: This work was supported mainly by the Administración Nacional de Laboratorios e Institutos de Salud (ANLIS) “Dr. Carlos Malbrán”. Further details of fundings sources is included in the appendix.Fil: Iglesias, Ayelén Aluminé. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; ArgentinaFil: Periolo, Natalia. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bellomo, Carla María. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; ArgentinaFil: Lewis, Lorena Cecilia. Provincia del Chubut. Servicio de Salud Mental. Hospital Zonal de Esquel; ArgentinaFil: Olivera, Camila Paula. Provincia del Chubut. Servicio de Salud Mental. Hospital Zonal de Esquel; ArgentinaFil: Rosario Anselmo, Constanza. Provincia del Chubut. Servicio de Salud Mental. Hospital Zonal de Esquel; ArgentinaFil: García, Marina. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Coelho, Rocío María. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; ArgentinaFil: Alonso, Daniel Oscar. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; ArgentinaFil: Dighero Kemp, Bonnie. National Institute Of Allergy And Infectious Diseases; Estados UnidosFil: Sharma, Heema. National Institute Of Allergy And Infectious Diseases; Estados UnidosFil: Kuhn, Jens H.. National Institute Of Allergy And Infectious Diseases; Estados UnidosFil: Di Paola, Nicholas. Center For Genome Sciences, U.s. Army Medical Research; Estados UnidosFil: Sanchez Lockhart, Mariano. Center For Genome Sciences, U.s. Army Medical Research; Estados UnidosFil: Palacios, Gustavo. Center For Genome Sciences, U.s. Army Medical Research; Estados UnidosFil: Schierloh, Luis Pablo. Universidad Nacional de Entre Ríos. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática; ArgentinaFil: Martinez, Valeria Paula. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentin

Antigenic and genomic characterization of human influenza A and B viruses circulating in Argentina after the introduction of influenza A(H1N1)pdm09

This study was conducted as part of the Argentinean Influenza and other Respiratory Viruses Surveillance Network, in the context of the Global Influenza Surveillance carried out by the World Health Organization (WHO). The objective was to study the activity and the antigenic and genomic characteristics of circulating viruses for three consecutive seasons (2010, 2011 and 2012) in order to investigate the emergence of influenza viral variants. During the study period, influenza virus circulation was detected from January to December. Influenza A and B, and all current subtypes of human influenza viruses, were present each year. Throughout the 2010 post-pandemic season, influenza A(H1N1)pdm09, unexpectedly, almost disappeared. The haemagglutinin (HA) of the A(H1N1)pdm09 viruses studied were segregated in a different genetic group to those identified during the 2009 pandemic, although they were still antigenically closely related to the vaccine strain A/California/07/2009. Influenza A(H3N2) viruses were the predominant strains circulating during the 2011 season, accounting for nearly 76% of influenza viruses identified. That year, all HA sequences of the A(H3N2) viruses tested fell into the A/ Victoria/208/2009 genetic clade, but remained antigenically related to A/Perth/16/2009 (reference vaccine recommended for this three-year period). A(H3N2) viruses isolated in 2012 were antigenically closely related to A/Victoria/361/2011, recommended by the WHO as the H3 component for the 2013 Southern Hemisphere formulation. B viruses belonging to the B/Victoria lineage circulated in 2010. A mixed circulation of viral variants of both B/Victoria and B/Yamagata lineages was detected in 2012, with the former being predominant. A(H1N1)pdm09 viruses remained antigenically closely related to the vaccine virus A/California/7/2009; A(H3N2) viruses continually evolved into new antigenic clusters and both B lineages, B/Victoria/2/87-like and B/ Yamagata/16/88-like viruses, were observed during the study period. The virological surveillance showed that the majority of the circulating strains during the study period were antigenically related to the corresponding Southern Hemisphere vaccine strains except for the 2012 A(H3N2) viruses.Fil: Russo, Mara Laura. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pontoriero, Andrea. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; ArgentinaFil: Benedetti, Estefania. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; ArgentinaFil: Czech, Andrea. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; ArgentinaFil: Avaro, Martin. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; ArgentinaFil: Periolo, Natalia. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Campos, Ana M.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; ArgentinaFil: Savy, Vilma L.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; ArgentinaFil: Baumeister, Elsa. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio E Instituto de Salud "Dr. C. G. Malbran". Departamento Virus; Argentin

Surveillance of antiviral resistance markers in Argentina: detection of E119V neuraminidase mutation in a post-treatment immunocompromised patient

Although vaccines are the best means of protection against influenza, neuraminidase inhibitors are currently the main antiviral treatment available to control severe influenza cases. One of the most frequent substitutions in the neuraminidase (NA) protein of influenza A(H3N2) viruses during or soon after oseltamivir administration is E119V mutation. We describe the emergence of a mixed viral population with the E119E/V mutation in the NA protein sequence in a post-treatment influenza sample collected from an immunocompromised patient in Argentina. This substitution was identified by a real-time reverse transcriptase polymerase chain reaction (RT-PCR) protocol and was confirmed by direct Sanger sequencing of the original sample. In 2014, out of 1140 influenza samples received at the National Influenza Centre, 888 samples (78%) were A(H3N2) strains, 244 (21.3%) were type B strains, and 8 (0.7%) were A(H1N1)pdm09 strains. Out of 888 A(H3N2) samples, 842 were tested for the E119V substitution by quantitative RT-PCR: 841 A(H3N2) samples had the wild-type E119 genotype and in one sample, a mixture of viral E119/ V119 subpopulations was detected. Influenza virus surveillance and antiviral resistance studies can lead to better decisions in health policies and help in medical treatment planning, especially for severe cases and immunocompromised patients

The simultaneous presence of IL-1B and TNFA two-positions risk haplotypes enhances the susceptibility for celiac disease

To assess the joint contribution of interleukin 1 beta (IL-1B) and tumor necrosis factor alpha (TNF?) to the genetic risk of developing celiac disease (CD), we analyzed four biallelic polymorphisms of TNFA and IL-1B genes in 228 patients and 244 healthy controls. The individual contribution of TNFA -308A and IL-1B -511C alleles was weak (OR 1.47 and 1.66, respectively) and was null for TNFA -238 A/G and IL-1B +3953 C/T single nucleotide polymorphisms (SNPs). Due to the potential linkage disequilibrium between TNFA, human leukocyte antigen (HLA) -DQA1 and HLA-DQB1 genes, only individuals carrying DQ2 antigen (DQ2-positive) were considered to perform haplotype analyses. Two-position risk haplotypes were first defined by the combined presence of -511C and +3953T alleles for IL-1B (OR 9.402) or -308A and -238A alleles for TNFA (OR 15.389). The TNFA/IL-1B combined haplotype-stratified association analysis showed that the simultaneous presence of TNFA risk and IL-1B non-risk haplotypes (OR 13.32) but not TNFA non-risk and IL-1B risk haplotypes (OR 0.71) is associated with CD. Interestingly, our data suggest that the coexistence of both risk haplotypes seems to work synergistically (OR 29.59), which enhances the risk of developing CD. © 2008 Elsevier Ltd. All rights reserved

Influenza virus surveillance in Argentina during the 2012 season: antigenic characterization, genetic analysis and antiviral susceptibility

Fil: Benedetti, Estefanía. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Servicio de Virosis Respiratoria; Argentina.Fil: Daniels, Rodney S. The Francis Crick Institute. Mill Hill Laboratory, The Ridgeway, Mill Hill, Londres; Reino Unido.Fil: Pontoriero, Andrea. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Servicio de Virosis Respiratoria; Argentina.Fil: Russo, Mara. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Servicio de Virosis Respiratoria; Argentina.Fil: Avaro, Martín. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Servicio de Virosis Respiratoria; Argentina.Fil: Czech, A. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Servicio de Virosis Respiratoria; Argentina.Fil: Campos, Ana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Servicio de Virosis Respiratoria; Argentina.Fil: Periolo, Natalia. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Servicio de Virosis Respiratoria; Argentina.Fil: Gregory, V. The Francis Crick Institute. Mill Hill Laboratory, The Ridgeway, Mill Hill, Londres; Reino Unido.Fil: McCauley, John W. The Francis Crick Institute. Mill Hill Laboratory, The Ridgeway, Mill Hill, Londres; Reino Unido.Fil: Baumeister, Elsa G. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Servicio de Virosis Respiratoria; Argentina.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