ABSTRACT
@#Influenza is a highly contagious viral illness characterized by fever, cough, headache and myalgia. The influenza virus is a segmented ribonucleic acid (RNA) virus that can infect both humans and animals, and the capacity for reassortment when multiple viruses infect the same cell has led – and will continue to lead – to the development of novel pandemic influenza A viruses. The disease is generally self-limiting, although complications and deaths can occur, particularly in children < two years of age, adults >65 years of age, pregnant women, and immunosuppressed individuals. Specific antiviral therapy is available, including oseltamivir in Singapore, and is recommended for severe disease as well as those with higher likelihood for developing complications from influenza. In addition to hand hygiene and respiratory etiquette, antiviral prophylaxis may reduce the impact and burden of influenza in household and institutional settings. However, the primary means for preventing influenza is via annual vaccination in those above the age of two years. The influenza vaccine, while having variable efficacy depending on antigenic matching with circulating viruses each year, is safe and cost-effective at the population level.
ABSTRACT
To investigate the genetic characteristics of human influenza type B viruses circulating in Chungbuk province, Korea, we tested 510 clinical samples of nasopharyngeal suction from pediatric patients diagnosed with respiratory illness between June 2007 and June 2008. Twelve out of thirty-six isolates were identified as type B influenza virus by RT-PCR and sequencing analysis. Interestingly, genetic characterization of type B viruses isolated in this study revealed that all type B influenza viruses were the Yamagata lineages, a vaccine strains of southern hemisphere during 2007~2008, rather than the Victoria lineage of northern hemisphere during 2007~2008. Furthermore, there were a total of twelve unique mutations (HA: H40Y, D/G230S, V252M and K272R and NA: P3H, P/T/S42Q, N59S) occurred in our type B isolates. These results suggest that relative high prevalence of type B viruses in Korea during 2007~2008 season might be due to the wrong vaccine strains selection. Taken together, the results of this study demonstrate continuous evolutions of human type B viruses by antigenic drift and also highlight the need to closely monitoring of influenza viruses to aid the early detection of potentially pandemic strains as well as underscore the need for new therapeutics.