title: Phylogenetic studies of influenza B viruses isolated in southern Africa: 1998-2001.
abstract: Influenza B viruses isolated in southern Africa during the period from 1998 to 2001 were analysed by sequence analysis of the viral haemagglutinin HA1 subunit and the phylogenetic relationships were determined. Influenza B activity varied considerably in South Africa during the 4-year study period with no activity detected in 2000. Phylogenetic analysis revealed that viruses isolated in 1998 from a localised outbreak in Durban belonged to two distinct sub-lineages. Some of the influenza B viruses isolated throughout South Africa in 1999 as well as several viruses obtained from Mozambique in the same year were closely related to the B/Yamanashi/166/98-like viruses. In contrast, the majority of the 1999 isolates, represented by B/Johannesburg/5/99, exhibited considerable drift from the B/Yamanashi/166/98 stain. The viruses isolated during the 2001 season fell into two sub-lineages, one of which had evolved from the B/Johannesburg/5/99-like viruses and the other which had evolved from the group of viruses that included one of the 1998 Durban isolates. These molecular epidemiological studies reveal a diverse and complex pattern of influenza B virus strains circulating in southern Africa.
authors.affiliation: National Institute for Communicable Diseases, Private Bag X4, Sandringham 2131, South Africa. terryb@nicd.ac.za
authors.forename: Terry G
authors.initials: TG
authors.lastname: Besselaar
authors.forename: Lizelle
authors.initials: L
authors.lastname: Botha
authors.forename: Jo M
authors.initials: JM
authors.lastname: McAnerney
authors.forename: Barry D
authors.initials: BD
authors.lastname: Schoub
mesh_terms: D000353:Africa, Southern / Q000453:epidemiology; D000595:Amino Acid Sequence; D004196:Disease Outbreaks; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D009981:Influenza B virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus