Analysis of a Local HIV-1 Epidemic in Portugal Highlights Established Transmission of Non-B and Non-G Subtypes

Abstract

The existing data support Portugal as the western European country with the highest HIV-1 subtype diversity. However, detailed phylogenetic studies of Portuguese HIV-1 epidemics are still scarce. Thus, our main goal was to analyze the phylodynamics of a local HIV-1 infection in the Portuguese region of Minho. Molecular epidemiological analysis was applied to data from 289 HIV-1-infected individuals followed at the reference hospital of the province of Minho, Portugal, at which isolated viruses had been sequenced between 2000 and 2012. Viruses of the G (29.1%) and B (27.0%) subtypes were the most frequent, followed by recombinant forms (17.6%) and the C (14.5%), F1 (7.3%), and A1 (4.2%) subtypes. Multinomial logistic regression revealed that the odds of being infected with the A1 and F1 subtypes increased over the years compared with those with B, G, or C subtypes or recombinant viruses. As expected, polyphyletic patterns suggesting multiple and old introductions of the B and G subtypes were found. However, transmission clusters of non-B and non-G viruses among native individuals were also found, with the dates of the most recent common ancestor estimated to be in the early 2000s. Our study supports that the HIV-1 subtype diversity in the Portuguese region of Minho is high and has been increasing in a manner that is apparently driven by factors other than immigration and international travel. Infections with A1 and F1 viruses in the region of Minho are becoming established and are mainly found in sexually transmitted clusters, reinforcing the need for more efficacious control measures targeting this infection route.

Molecular epidemiology of HIV-1 infection in Europe: An overview

“…Non-B and CRF clades have mainly been associated with immigrants, heterosexual transmission and male gender. Conversely, there is evidence for regional dispersal among native population of subtype A in Greece and subtype G in Portugal (Carvalho et al, 2015;Esteves et al, 2003;Paraskevis et al, 2007). Notably and unlike any other European country, in Romania the F clade (subsubtype F1) has predominated since the begging of the epidemic in the late-1980s with as little as 5% of characterised HIV-1 strains belonging to non-F1 subtypes (Apetrei et al, 1998;Stanojevic et al, 2012).…”

“…1%, 1997-2001) (Esteves et al, 2003), unlike any other neighbouring or not country in the European continent. Although polyphyletic analyses suggested multiple and old introductions of the B and G clades, as expected, additional non-B and non-G clades have established local epidemics among native individuals, with the dates of the most recent common ancestor estimated to be in the early 2000s (Carvalho et al, 2015). As in Portugal, the introduction of non-B clades in neighbouring Spain, was also documented in the mid to late-1990s, mainly among immigrants (Soriano et al, 1997).…”

Overview of HIV molecular epidemiology among people who inject drugs in Europe and Asia

“…Spain and Portugal experienced an enormous HIV spread among PWID in the 1990s and their epidemics are characterized by substantial viral diversity and distinct molecular properties compared to other European countries (Carvalho et al, 2015). Non-B subtypes were present among HIV+ PWID in the early years of the epidemic in Spain (Lospitao et al, 2005).…”

“…Non-B subtypes were present among HIV+ PWID in the early years of the epidemic in Spain (Lospitao et al, 2005). Non-B subtypes, and especially subtype G (21-24%), were also very prevalent among PWID in Portugal in the late 1990s (Esteves et al, 2003, 2002), while subtype G is still found in around 30% of all diagnoses (Carvalho et al, 2015; Palma et al, 2007). Subtype G and other non-B subtypes were introduced in Portugal following intense migration between Portugal and its former African colonies in the late 1970s and early 1980s, especially because of the Portuguese Colonial War that involved multiple theatres of operation including Angola with a high degree of HIV-1 group M genetic diversity (Bártolo et al, 2009; Carvalho et al, 2015; Vermund and Leigh-Brown, 2012).…”

“…Non-B subtypes, and especially subtype G (21-24%), were also very prevalent among PWID in Portugal in the late 1990s (Esteves et al, 2003, 2002), while subtype G is still found in around 30% of all diagnoses (Carvalho et al, 2015; Palma et al, 2007). Subtype G and other non-B subtypes were introduced in Portugal following intense migration between Portugal and its former African colonies in the late 1970s and early 1980s, especially because of the Portuguese Colonial War that involved multiple theatres of operation including Angola with a high degree of HIV-1 group M genetic diversity (Bártolo et al, 2009; Carvalho et al, 2015; Vermund and Leigh-Brown, 2012). Subtype G, which also circulates among PWID in Spain (Delgado et al, 2002; Pérez-Alvarez et al, 2003), recombined with subtype B, probably in Portugal early in the history of the epidemic, creating CRF14_BG that has been detected in Portugal, at low prevalence in the region of Galicia, Spain, and in some other European settings (Bártolo et al, 2011; Carvalho et al, 2015; Duque et al, 2003; Harris et al, 2005; Thomson et al, 2001).…”