title: Prospective surveillance and molecular characterization of seasonal influenza in a university cohort in Singapore.
abstract: BACKGROUND
  Southeast Asia is believed to be a potential locus for the emergence of novel influenza strains, and therefore accurate sentinel surveillance in the region is critical. Limited information exists on sentinel surveillance of influenza-like illness (ILI) in young adults in Singapore in a University campus setting. The objective of the present study was to determine the proportion of ILI caused by influenza A and B viruses in a university cohort in Singapore.
  
  
  RESULTS
  We conducted a prospective surveillance study from May through October 2007, at the National University of Singapore (NUS). Basic demographic information and nasopharyngeal swabs were collected from students and staff with ILI. Reverse-transcriptase PCR (RT-PCR) and viral isolation were employed to detect influenza viruses. Sequencing of hemagglutinin (HA) and neuraminidase (NA) genes of some representative isolates was also performed. Overall proportions of influenza A and B virus infections were 47/266 (18%) and 9/266 (3%) respectively. The predominant subtype was A/H3N2 (55%) and the rest were A/H1N1 (45%). The overall sensitivity difference for detection of influenza A viruses using RT-PCR and viral isolation was 53%. Phylogenetic analyses of HA and NA gene sequences of Singapore strains showed identities higher than 98% within both the genes. The strains were more similar to strains included in the WHO vaccine recommendation for the following year (2008). Genetic markers of oseltamivir resistance were not detected in any of the sequenced Singapore isolates.
  
  
  CONCLUSIONS
  HA and NA gene sequences of Singapore strains were similar to vaccine strains for the upcoming influenza season. No drug resistance was found. Sentinel surveillance on university campuses should make use of molecular methods to better detect emerging and re-emerging influenza viral threats.
authors: Department of Medicine, National University of Singapore, Singapore, Singapore.
authors: Ramandeep Kaur
authors: RK
authors: Virk
authors: Department of Medicine, National University of Singapore, Singapore, Singapore.
authors: Paul Anantharajah
authors: PA
authors: Tambyah
authors: Experimental Therapeutics Centre, Agency for Science, Technology and Research, Singapore, Singapore.
authors: Masafumi
authors: M
authors: Inoue
authors: Detection and Diagnostics Laboratory, DSO National Laboratories, Singapore, Singapore.
authors: Elizabeth Ai-Sim
authors: EA
authors: Lim
authors: Detection and Diagnostics Laboratory, DSO National Laboratories, Singapore, Singapore.
authors: Ka-Wei
authors: KW
authors: Chan
authors: University Health Centre, National University of Singapore, Singapore, Singapore.
authors: Catherine
authors: C
authors: Chua
authors: Detection and Diagnostics Laboratory, DSO National Laboratories, Singapore, Singapore ; Department of Epidemiology and Public Health, National University of Singapore, Singapore, Singapore.
authors: Boon-Huan
authors: BH
authors: Tan
mesh_terms: D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D015331:Cohort Studies; D024882:Drug Resistance, Viral / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D014644:Genetic Variation; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D009980:Influenza A virus / Q000302:isolation & purification / Q000502:physiology; D007251:Influenza, Human / Q000188:drug therapy / Q000453:epidemiology* / Q000235:genetics* / Q000821:virology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics; D053139:Oseltamivir / Q000494:pharmacology / Q000627:therapeutic use; D010802:Phylogeny; D011446:Prospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons; D018571:Sentinel Surveillance; D012846:Singapore / Q000453:epidemiology; D014495:Universities; D055815:Young Adult
chemical_list: D004791:Enzyme Inhibitors; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D053139:Oseltamivir; D009439:Neuraminidase