title: Characteristics and spread to the native population of HIV-1 non-B subtypes in two European countries with high migration rate.
abstract: BACKGROUND
  Non-B subtypes account for at least 50 % of HIV-1 infections diagnosed in Belgium and Luxembourg. They are considered to be acquired through heterosexual contacts and infect primarily individuals of foreign origin. Information on the extent to which non-B subtypes spread to the local population is incomplete.
  
  
  METHODS
  Pol and env gene sequences were collected from 410 non-subtype B infections. Profound subtyping was performed using 5 subtyping tools and sequences of both pol and env. Demographic information, disease markers (viral load, CD4 count) and viral characteristics (co-receptor tropism) were compared between subtypes. Maximum likelihood phylogenetic trees were constructed and examined for clustering.
  
  
  RESULTS
  The majority of non-B infections were diagnosed in patients originating from Africa (55.8 %), individuals born in Western Europe represented 30.5 %. Heterosexual transmission was the most frequently reported transmission route (79.9 %), MSM transmission accounted for 12.2 % and was significantly more frequently reported for Western Europeans (25.7 % versus 4.3 % for individuals originating from other regions; p < 0.001). Subtypes A and C and the circulating recombinant forms CRF01_AE and CRF02_AG were the most represented and were included in the comparative analysis. Native Western Europeans were underrepresented for subtype A (14.5 %) and overrepresented for CRF01_AE (38.6 %). The frequency of MSM transmission was the highest for CRF01_AE (18.2 %) and the lowest for subtype A (0 %). No differences in age, gender, viral load or CD4 count were observed. Prevalence of CXCR4-use differed between subtypes but largely depended on the tropism prediction algorithm applied. Indications for novel intersubtype recombinants were found in 20 patients (6.3 %). Phylogenetic analysis revealed only few and small clusters of local transmission but could document one cluster of CRF02_AG transmission among Belgian MSM.
  
  
  CONCLUSIONS
  The extent to which non-B subtypes spread in the native Belgian-Luxembourg population is higher than expected, with 30.5 % of the non-B infections diagnosed in native Western Europeans. These infections resulted from hetero- as well as homosexual transmission. Introduction of non-B variants in the local high at risk population of MSM may lead to new sub-epidemics and/or increased genetic variability and is an evolution that needs to be closely monitored.
authors.affiliation: Aids Reference Laboratory, Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, De Pintelaan 185-Blok A, B-9000, Ghent, Belgium. kenny.dauwe@ugent.be.
authors.forename: Kenny
authors.initials: K
authors.lastname: Dauwe
authors.affiliation: Aids Reference Laboratory, Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, De Pintelaan 185-Blok A, B-9000, Ghent, Belgium. virginie.mortier@ugent.be.
authors.forename: Virginie
authors.initials: V
authors.lastname: Mortier
authors.affiliation: Aids Reference Laboratory, Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, De Pintelaan 185-Blok A, B-9000, Ghent, Belgium. marlies.schauvliege@ugent.be.
authors.forename: Marlies
authors.initials: M
authors.lastname: Schauvliege
authors.affiliation: Aids Reference laboratory, Department of Clinical Sciences, Institute of Tropical Medicine, Nationalestraat 155, B-2000, Antwerp, Belgium. avdheuvel@itg.be.
authors.forename: Annelies
authors.initials: A
authors.lastname: Van Den Heuvel
authors.affiliation: Aids Reference laboratory, Department of Clinical Sciences, Institute of Tropical Medicine, Nationalestraat 155, B-2000, Antwerp, Belgium. kfransen@itg.be.
authors.forename: Katrien
authors.initials: K
authors.lastname: Fransen
authors.affiliation: Laboratory of Retrovirology, Department of Infection and Immunity, Luxembourg Institute of Health, Val Fleuri 84, L-1526, Luxembourg, Luxembourg. jean-yves.servais@crp-sante.lu.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Servais
authors.affiliation: Laboratory of Retrovirology, Department of Infection and Immunity, Luxembourg Institute of Health, Val Fleuri 84, L-1526, Luxembourg, Luxembourg. danielle.perezbercoff@crp-sante.lu.
authors.forename: Danielle Perez
authors.initials: DP
authors.lastname: Bercoff
authors.affiliation: Laboratory of Retrovirology, Department of Infection and Immunity, Luxembourg Institute of Health, Val Fleuri 84, L-1526, Luxembourg, Luxembourg. carole.devaux@crp-sante.lu.
authors.forename: Carole
authors.initials: C
authors.lastname: Seguin-Devaux
authors.affiliation: Aids Reference Laboratory, Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, De Pintelaan 185-Blok A, B-9000, Ghent, Belgium. chris.verhofstede@ugent.be.
authors.forename: Chris
authors.initials: C
authors.lastname: Verhofstede
mesh_terms: D000328:Adult; D000349:Africa; D001530:Belgium / Q000453:epidemiology; D018791:CD4 Lymphocyte Count; D016000:Cluster Analysis; D005060:Europe; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000635:transmission*; D015497:HIV-1 / Q000235:genetics* / Q000472:pathogenicity; D020010:Heterosexuality; D006801:Humans; D008189:Luxembourg / Q000453:epidemiology; D008297:Male; D010802:Phylogeny; D019718:Receptors, CXCR4; D012189:Retrospective Studies; D014171:Transients and Migrants; D054299:env Gene Products, Human Immunodeficiency Virus / Q000235:genetics; D054302:pol Gene Products, Human Immunodeficiency Virus / Q000235:genetics
chemical_list: D019718:Receptors, CXCR4; D054299:env Gene Products, Human Immunodeficiency Virus; D054302:pol Gene Products, Human Immunodeficiency Virus