ML trees of sequences of HIV-1 isolates from databases (all from Portugal) or obtained by us (from Spain) clustering with the BG recombinant virus 9196_01 in (a) PR-RT and/or the (b) V3 region.

<p>Sequences obtained in this study are in bold type. HXB2 positions delimiting the analyzed segments are in parentheses. Countries of collection of database viruses of subtype G in PR-RT and of subtype B in V3 are indicated with the two-letter ISO code. Only bootstrap values ≥70% are shown.</p

Analysis of the relationship of CRF73_BG with CRF14_BG.

<p>(a) ML tree of concatenated subtype G fragments of X3208 and 9196_01, analyzed with G_Ib and CRF14_BG viruses. Countries of collection of subtype G viruses are indicated with the two-letter ISO code. (b) ML tree of the 5’ <i>env</i> fragment. (c) ML tree of the subtype B 3’ <i>env</i> fragment. HXB2 positions delimiting the analyzed segments in (b) and (c) are in parentheses. CRF73_BG viruses are in bold type. Countries of collection of database viruses of subtype G viruses in (a) and of subtype B viruses in (b) and (c) are indicated with the two-letter ISO code. Only bootstrap values ≥70% are shown.</p

Intersubtype breakpoint locations in HIV-1 BG recombinant viruses analyzed in this study, including all available CRF14_BG viruses sequenced in near full-length genomes, as determined with jpHMM.

<p>Intersubtype breakpoint locations in HIV-1 BG recombinant viruses analyzed in this study, including all available CRF14_BG viruses sequenced in near full-length genomes, as determined with jpHMM.</p

Identification of an HIV-1 BG Intersubtype Recombinant Form (CRF73_BG), Partially Related to CRF14_BG, Which Is Circulating in Portugal and Spain

<div><p>HIV-1 exhibits a characteristically high genetic diversity, with the M group, responsible for the pandemic, being classified into nine subtypes, 72 circulating recombinant forms (CRFs) and numerous unique recombinant forms (URFs). Here we characterize the near full-length genome sequence of an HIV-1 BG intersubtype recombinant virus (X3208) collected in Galicia (Northwest Spain) which exhibits a mosaic structure coincident with that of a previously characterized BG recombinant virus (9601_01), collected in Germany and epidemiologically linked to Portugal, and different from currently defined CRFs. Similar recombination patterns were found in partial genome sequences from three other BG recombinant viruses, one newly derived, from a virus collected in Spain, and two retrieved from databases, collected in France and Portugal, respectively. Breakpoint coincidence and clustering in phylogenetic trees of these epidemiologically-unlinked viruses allow to define a new HIV-1 CRF (CRF73_BG). CRF73_BG shares one breakpoint in the envelope with CRF14_BG, which circulates in Portugal and Spain, and groups with it in a subtype B envelope fragment, but the greatest part of its genome does not appear to derive from CRF14_BG, although both CRFs share as parental strain the subtype G variant circulating in the Iberian Peninsula. Phylogenetic clustering of partial <i>pol</i> and <i>env</i> segments from viruses collected in Portugal and Spain with X3208 and 9691_01 indicates that CRF73_BG is circulating in both countries, with proportions of around 2–3% Portuguese database HIV-1 isolates clustering with CRF73_BG. The fact that an HIV-1 recombinant virus characterized ten years ago as a URF has been shown to represent a CRF suggests that the number of HIV-1 CRFs may be much greater than currently known.</p></div

Analyses of partial genome sequences of BG recombinant viruses related to X3208 and 9196_01.

<p>(a) Bootscan analyses of <i>pol</i> fragments of X3121, from Spain, and 753_G_0_Rennes, from France. (b) ML tree of the integrase subtype B fragment of X3121 and 753_G_0_Rennes, showing clustering with 9196_01 and X3208. HXB2 positions delimiting the analyzed segment are in parentheses. Only bootstrap values ≥70% are shown. (c) Bootscan analysis of the envelope gene of VLGC_PT_BG3, from Portugal. In the bootscanning graphs, the position in the horizontal axis represents the midpoint of the sliding window in the proviral HXB2 genome.</p

Mosaic structure of CRF73_BG.

<p>Breakpoint positions, according to HXB2 genome numeration, are indicated.</p

Bayesian skyline plot of the population growth of the subtype F cluster.

<p>The black line represents the median estimate of the effective number of infections through time (logarithmic scale) and the shaded area represents the 95% HPD credibility interval. The horizontal axis represents calendar years.</p

Distribution of viruses of the subtype F cluster sequenced by us according to city of sample collection.

<p>Distribution of viruses of the subtype F cluster sequenced by us according to city of sample collection.</p

Maximum clade credibility tree of PR-RT sequences of the subtype F Western European cluster and Galician subcluster.

<p>Nodes supported by PP = 1 and PP = 0.95–0.99 are marked with filled and unfilled circles, respectively. Colors of terminal and internal branches represent sampling locations and most probable locations of the corresponding nodes, respectively, according to the legend on the right. For the nodes corresponding to the Galician subcluster and the Western European cluster, the posterior probabilities for the most probable locations and the tMRCAs are indicated above the subtending branches (95% HPD intervals are in parentheses).</p

Maximum likelihood trees of sequences from databases belonging to the Western European subtype F cluster.

<p>The trees correspond to genome segments in (a) p17^gag (HXB2 positions 790–1185), (b) p24^gag (HXB2 positions 1575–2042), (c) reverse transcriptase (HXB2 positions 2637–3278), (d) <i>env</i> V3 region (HXB2 positions 6709–7448), and (e) <i>nef</i> (HXB2 positions 8797–9417). References for the subtype F cluster are near full-length genome sequences obtained by us, with names beginning with X, P or VA, with ‘i’ ending denoting those derived from cultured isolates. Database viruses branching in the subtype F cluster are in bold type. Countries of sample collection of database viruses are indicated with the ISO two-letter codes: BE, Belgium; BR: Brazil; CH, Switzerland; ES, Spain; FR, France; GB, United Kingdom. Cities of sample collection of database viruses of the subtype F cluster, when known, are in parentheses. Only bootstrap values ≥70% are shown.</p