Phylogeny of HIV-1 subtype B in Denmark year 2001-2003

Poster number: 10

Audelin, A. M.(1), Skovgaard, O. (1), Petersen, A. B (2). & Jørgensen, L. B. (2)

  1. Department of Life Sciences and Chemistry, Roskilde University Centre, Denmark
  2. Statens Serum Institut, Dept. of Virology, Denmark

A total of 235 POL sequences were collected from untreated HIV-1 patients in the period 2001-2003 as part of a national surveillance programme. In order to study the epidemiology of the Danish HIV-1 subtype B population the sequences were compared in phylogenetic analysis. The aim was to evaluate if the Danish HIV-1 population can be subdivided according to risk group (IVDU, MSM, HET) or geographical locations.

The POL sequences were compared by phylogenetic methods using neighbour-joining, maximum likelihood and maximum parsimony algorithms integrated in the PHYLIP package version 3.6b. In the resulting phylogenetic trees no clear separation was seen in the Danish HIV-1 subtype B population neither in terms of geography or risk group. The epidemic is characterised by multiple introductions of different viral strains from abroad.

In 2002 and 2003, but not in 2001, a minor cluster tendency was seen for the IVDU risk group. The results may be due to a change in behaviour during the change of the millennium, perhaps caused by a governmental prevention program promoting the use of sterile syringe among drug users. The lack of geographical separation of the POL sequences suggests that the epidemic of the HIV-1 subtype B in Denmark is not composed of smaller local epidemics. The majority (86%) of all new HIV-1 infections in Denmark are reported from the capital area. The epidemic is easily spread to the rest of the country due to the small size of Denmark.

The geographical results are in correlation to the epidemical spread reported in other European countries (Op de Coul et al., 2001). However, the risk group results are in contrast to studies of the HIV-1 population in Holland and UK, where the population can be separated according to risk group (Lukashov et. al,1998; Brown et al, 1997).