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Influenza B viruses in the population of province of Vojvodina during the 2012/2013 season: Differentiation of B/Yamagata and B/Victoria lineages by real-time RT-PCR, antigenic and phylogenetic characterization

Radovanov Jelena (Institute of Public Health of Vojvodina, Novi Sad)
Milošević Vesna (Institute of Public Health of Vojvodina, Novi Sad + Medical Faculty, Novi Sad)
Hrnjaković-Cvjetković Ivana (Institute of Public Health of Vojvodina, Novi Sad + Medical Faculty, Novi Sad)
Ristić Mioljub (Institute of Public Health of Vojvodina, Novi Sad + Medical Faculty, Novi Sad)
Đilas Milan (Institute of Public Health of Vojvodina, Novi Sad)
Nikolić Nataša (Institute of Public Health of Vojvodina, Novi Sad)
Patić Aleksandra (Institute of Public Health of Vojvodina, Novi Sad + Medical Faculty, Novi Sad)
Kovačević Gordana (Institute of Public Health of Vojvodina, Novi Sad)
Jovanović-Galović Aleksandra (Institute of Public Health of Vojvodina, Novi Sad)
Petrović Tamaš (Scientific Veterinary Institute Novi Sad, Novi Sad)
Mikić Sandra Stefan (Medical Faculty, Novi Sad + Clinic for Infectious Diseases, Clinical Center of Vojvodina, Novi Sad)

Introduction. At present, two phylogenetically distinct influenza B virus lineages, B/Yamagata and B/ Victoria, co-circulate worldwide and can cause significant morbidity and mortality. Objective. The aim of this study was to determine the prevalences of two influenza B virus lineages in the population of Vojvodina and to identify their antigenic and phylogenetic properties. Methods. A total of 369 and 334 nasopharyngeal, or nasal/throat swab samples, collected during the 2012/2013 and 2013/2014 seasons, respectively, were tested using specific singleplex influenza A, influenza B, influenza B/Yamagata and influenza B/Victoria real-time reverse transcription polymerase chain reaction (RT-PCR) assays. Antigenic and genetic testing were done by hemagglutination inhibition assay and hemagglutinin and neuraminidase gene sequence analysis, respectively. Results. During the 2012/2013 season, influenza B viruses were present in 53.4% (101/189) of influenza positive samples. The B/Yamagata-like viruses (81.2%) significantly predominated over the B/Victoria-like viruses (18.8%). Comparing to B/Victoria-like positive patients, among B/Yamagata-like positive patients, children 5-14 years of age were significantly more represented (5.3% vs. 35.4%, respectively), as well as patients with mild form of illness (15.8% vs. 45.1%, respectively). The results of sequence analysis and antigenic testing showed that tested viruses were not closely related to B/Wisconsin/1/2010, the vaccine virus for 2012/2013. During the 2013/2014 season influenza B viruses were not detected. Conclusion. The results of this study confirmed the health significance of influenza B viruses and indicated that B/Yamagata-like viruses were significantly more prevalent than B/Victoria lineage viruses, during the 2012/2013 season. They also showed a sub-optimal match between the tested viruses and the vaccine virus for season 2012/2013.

Keywords: influenza B, acute respiratory infections, epidemic, real-time RT-PCR

Projekat Ministarstva nauke Republike Srbije, br. TR31084