Iris Hasibra-Hatibi1, Artan Simaku1, Silva Bino1,2
1Institute of Public Health, Tirana, Albania;
2Faculty of Medicine, University of Medicine, Tirana, Albania.
Introduction and objectives: In order to evaluate the epidemiology of influenza A and its surface antigens (haemagglutinin and neuraminidase) diagnosis and virological surveillance of influenza is essential for detecting novel genetic variants causing epidemic potential. This investigation aims to give a rationale for exploring the molecular epidemiology and variant evolution analysis of A/H1N1pdm09 viruses during 2009-2018 influenza season in Albania.
Methods: This work describes the peculiarities of phylogenetic and genetic properties of HA and NA spike proteins of influenza A/H1N1 pdm09 viruses noted in the strains laboratory confirmed and circulating in Albania. For this study period we have analyzed the samples collected from the virological surveillance in Albania and the phylogenetic and genetic analyses conducted at the WHO Collaborative Centers in London and Atlanta.
Results: During the post-pandemic phase (2009-2010) the antigenic characterization analyzes of A/H1N1pdm09 viruses showed good matching properties with the group of reference viruses (including the vaccine virus A/California/7/2009). Phylogenetic analysis of the HA and NA genes in the next seasons indicated positioning of these viruses to the group 6B (2013-2014 influenza season) and later in the season 2015-2016 in the subgroup 6B.1 (introduction of a new potential glycosylation site) which have caused problems in many parts of the world. From the sequence analyses of 2017-2018 season it has been seen an exception on one isolate and two clinical samples. All had HA genes in the 6B.1 subgroup but with additional substitutions, one had the substitution L38Q in HA2 and two shared the substitutions S183P, E235D, N260D in HA1 and V193A in HA2. The NA genes clustered similarly and one had the substitution T16A and two shared the substitution N222D. One of these three findings is chosen from the WHO CC in London as representative to be suitable for making an egg isolate for starting a candidate vaccine virus development.
Conclusion: The results of this investigation confirm the necessity of constant regular antigenic and molecular surveillance of circulating seasonal influenza viruses.
Key words: influenza, molecular surveillance, vaccine virus.