For additional information, please contact Raquel Guiomar (National Institute of Health Dr. Ricardo Jorge / Portuguese NIC) raquel.guiomar@insa.min-saude.pt ; Tel.: (+351) 217519216 Background Respiratory syncytial virus (RSV) is one of the most frequent and important respiratory viral agent that causes respiratory infection complications in younger children and elderly. RSV has an autumn / winter seasonality. Genetic diversity in both of RSV A and B subtypes increased in last years with the spread of new genotypes. This study aims to describe the genetic variability of RSV during 2015/2016 season in Portugal and correlate the circulating genotypes with detected ones in previous seasons. Will also be evaluated the association between genotype, clinical diagnosis and age. Materials and Methods • During 2015/16 winter season, between November/2015 and February/2016, 45 RSV were genetically characterized. • RSV positive respiratory samples were collected in two settings: children under 5 years old diagnosed by 5 hospital laboratories from the Portuguese Laboratory Network for the Diagnosis of Influenza Infection, and all age Influenza-like illness (ILI) patients reported by primary care health services diagnosed by the National Influenza Reference Laboratory. • All samples were irreversibly anonymized. • Demographic and clinical data were collected. • RSV detection was performed by real-time PCR and other biomolecular methods. • RSV genotype was assigned by the nucleotide sequence of the hypervariable C-terminal region of the G protein gene and the phylogenetic analysis was performed in MEGA 6.0. P. Cristóvão 1 , D. Pereira 1 , P. Pechirra 1 , J. Pereira-Vaz 2 , L. Correia 2 , F. Rodrigues 2 , G. Andrade 3 , R. Côrte-Real 4 , Paula Branquinho 4 , M. J. Peres 5 , R. Viseu 5 , M.J. Balseiro 6 , P. Mota 7 , R. Guiomar 1 Molecular characterization of respiratory syncytial virus during 2015-2016 season in Portugal 1 National Influenza and Other Respiratory Viruses Reference Laboratory, Infectious Diseases Department, National Institute of Health Dr. Ricardo Jorge, Lisboa, Portugal 2 Laboratory of Molecular Biology, Clinical Pathology Unit, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal 3 Laboratory of Molecular Biology, Clinical Pathology Unit, Centro Hospitalar do Funchal, Madeira, Portugal 4 Laboratory of Molecular Biology, Clinical Pathology Unit, Centro Hospitalar Lisboa Central, Lisboa, Portugal 5 Immunology and Molecular Biology Laboratory, Allergy and Clinical Immunology Department, Centro Hospitalar de Setúbal, Setúbal, Portugal 6 Pediatrics Department, Centro Hospitalar de Setúbal, Setúbal, Portugal 7 Microbiology Laboratory, Clinical Pathology Department, Hospital Senhora da Oliveira, Guimarães, Portugal Results • From 45 RSV genetically characterized, 31 (69%) were reported by hospitals, patients age ranged from newborn to 4 years old. From these, 25 (81%;25/31) patients were hospitalized, being the bronchiolitis the most frequent diagnosis. • 4 (31%) RSV cases came from primary care health services, patients age ranged from 3 to 83 and all had a clinical diagnosis of ILI. • Were included patients from both genders in equal proportions. • RSV A and B co-circulated during 2015/2016 season. • Were genetically characterized 21 (47%) RSV A and 24 (53%) RSV B. • 90% (19/21) of RSV A clustered in ON1 genotype, the others 2 clustered with NA1 genotype (Fig 1). • All RSV B present a BA-like genotype, 70% (17/24) were similar to BA9 and 30% (7/24) clustered with BA10 genotype (Fig 2). Conclusions • During 2015/2016 season was observed a co-circulation of RSVA and RSVB. In present study ON1genotype was predominant in circulation among RSVA, this was also detected as the major RSVA genotype at the global level. Only two RSVA belonged to NA1 genotype. In Portugal, NA1 was in circulation during 2010- 2012 period. Undetected since 2012, it seems to reappear during 2015/16 season. • All RSVB characterized belonged to BA genotypes, the majority clustered within BA9 genotype. BA10 genotype was also identified in circulation at low frequency. BA9 and BA10 were being found in co-circulation since 2011/12. • No association was found between age, clinical diagnosis and RSVA and B genotypes. • RSV has an important impact in children in high-risk groups highlighting the need off a continuous RSV surveillance each winter. Acknowledgments The authors would like to thank to the GP Sentinel network, Non-sentinel Influenza Network (Emergency and Obstetric Units) that contributed to the clinical and virological components of the National Influenza Surveillance Programme during 2015-2016 season. Figure 1 – Maximum kikelihood phylogenetic tree based on the C-terminal region of G protein coding sequence of detected RSV A. Was used the hasegawa-kishino-yano model, bootstrap values above 50 are shown (500 replicates). RSV A RSV B Figure 2 –Maximum kikelihood phylogenetic tree based on the C-terminal region of G protein coding sequence of detected RSV B. Was used the hasegawa-kishino-yano model, bootstrap values above 50 are shown (500 replicates). ON1 NA1 RSVB/Portugal/H4-5/2015-2016 RSVB/Portugal/H11-6/2015-2016 RSVB/Portugal/H11-11/2015-2016 RSVB/Portugal/H11-5/2015-2016 RSVB/Portugal/H16-7/2015-2016 RSVB/Portugal/H11-7/2015-2016 RSVB/Portugal/H17-5/2015-2016 RSVB/Portugal/H17-9/2015-2016 RSVB/Portugal/H17-2/2015-2016 RSVB/Portugal/H17-8/2015-2016 HM459876 _BA9 DQ227395_BA9 DQ227395_ BA9 RSVB/Portugal/H11-21/2015-2016 RSVB/Portugal/su242/2015-2016 RSVB/Portugal/H11-15/2015-2016 RSVB/Portugal/H11-16/2015-2016 RSVB/Portugal/H11-17/2015-2016 RSVB/Portugal/eva119/2015-2016 RSVB/Portugal/H11-3/2015-2016 FJ490354_ BA10 FJ490355_ BA10 HM459886_BA10 RSVB/Portugal/H11-8/2015-2016 RSVB/Portugal/H11-22/2015-2016 RSVB/Portugal/eva96/2015-2016 RSVB/Portugal/su293/2015-2016 RSVB/Portugal/H11-12/2015-2016 RSVB/Portugal/H11-13/2015-2016 RSVB/Portugal/H17-6/2015-2016 HM459866_BA7 HM459871_BA8 AB175820_BA5 AY927401_BA AY751111_BA6 DQ227389_BA2 DQ227408_BA4 DQ227381_BA3 GU550483_BA KC297490_BA AY333364_BA1 JN119979_SAB4 AF348813_SAB3 AF348821_SAB2 AY488805_URU1 AY660682_SAB1 AF065251CH93_GB2 KC297462_URU2 M73540_GB1 AF065250_GB1 M73542_GB1 AY488803_URU2 M17213 97 96 84 100 98 67 95 78 70 73 92 73 96 99 52 88 66 59 0,01 BA9 BA10 JX885735_ON1 JX885736_ON1 JX885734_ON1 JN257694 ON1A JX885733_ON1 JX885731_ON1 JX885730_ON1 JX885737_ON1 JX912356_ON1 JX885732_ON1 KC559440_ON1 RSVA/Portugal/eva95/2015-2016 JX912357_ON1 RSVA/Portugal/H11-14/2015-2016 RSVA/Portugal/H16-5/2015-2016 KF246638 _ON1C KF246641_ ON1C RSVA/Portugal/eva88/2015-2016 RSVA/Portugal/su201/2015-2016 RSVA/Portugal/gg25/2015-2016 RSVA/Portugal/H4-7/2015-2016 RSVA/Portugal/ms15/2015-2016 RSVA/Portugal/H17-10/2015-2016 RSVA/Portugal/su219/2015-2016 RSVA/Portugal/H16-6/2015-2016 RSVA/Portugal/H16-1/2015-2016 RSVA/Portugal/H16-3/2015-2016 RSVA/Portugal/H16-4/2015-2016 RSVA/Portugal/H16-2/2015-2016 RSVA/Portugal/H4-9/2015-2016 RSVA/Portugal/su235/2015-2016 AB761609_ ON1A JX912355_ON1 RSVA/Portugal/eva61/2015-2016 RSVA/Portugal/su132/2015-2016 RSVA/Portugal/eva80/2015-2016 RSVA/Portugal/H17-1/2015-2016 KC297305_NA1 KC297377_NA1 KC297301_NA1 KC297251_NA1 BJ/22998_NA1 NG01604_NA1 BJ/29240_NA3 KC297248_NA3 AB603443_NA2 AF512538_GA2 Z33422_GA2 BJ/F5166_NA4 BJ/36578_NA4 KC297324_NA4 AF065258_GA2 AF233900_GA2 Al19376-1_GA2 AF233918_GA6 AF233905_GA3 CN2395_GA3 Z33411_GA7 Z33417_GA7 Z33420_GA7 AF233904_GA7 AF348804_GA7 AF348807_SAA1 AF348810_SAA1 AF065254_GA4 AF233916_GA5 AY114150_ GA5 AY524593_GA5 X73352_GA5 Z33493_GA5 AF233917_GA1 X73350_GA1 X73354_GA1 Z33431_GA1 M11486PrototipoRSVA_A2 77 98 73 98 99 87 81 92 99 99 80 69 61 51 60 99 59 94 54 81 54 90 65 62 54 53 76 0,02 19th ESCV, Lisbon, 2016