517 
Although most HIV-1 infections in North America and Europe have involved subtype B, this appears to no longer be the case in Greece, study researchers have revealed.
“Our study documented a significant increase of HIV-1 subtype A that surpassed subtype B in the last years in Greece,” lead investigator Dr Dimitrios Paraskevis said.
“Importantly,” he added, “most of the subtype A infections — 91% – fell within a monophyletic cluster suggesting that most of the subtype A infections occur in the territory of Greece.”
Writing in the Journal of Infectious Diseases, Dr Paraskevis and Dr Angelos Hatzakis of Athens University and colleagues, noted that non-B HIV infection in European countries was mainly among heterosexuals, immigrants or intravenous drug users.
In a study of HIV subtypes in 1158 patients in Greece who had become infected between 1998 and 2005, the investigators found that non-B subtypes, particularly subtype A, became increasingly prevalent over time.
In fact, by 2004, subtype A was responsible for 42% of infections, compared to 33% for subtype B.
Further analysis indicated that the subtype A epidemic was the result of a single founder event, with the most recent common ancestor in Greece estimated to have appeared late in 1977.
“The characteristics of the HIV-1 epidemic in Greece raise concern about any future HIV-1 vaccination in Greece,” Dr Paraskevis said. “The viral characteristics – for example, pathogenicity and infectivity – of the HIV-1 subtype A versus B isolates”, now have to be considered.
In an accompanying editorial, Dr Michael M. Thomson and Dr Rafael Najera of Instituto de Salud Carlos III, Madrid, Spain, observed that the research “adds to the findings of other studies indicating a trend toward an increasing genetic complexity of HIV-1 epidemics in Europe”.
