High Frequency of Non-B Subtypes in Newly Diagnosed HIV-1 Infections in Switzerland

Abstract

HIV-1 subtypes were determined in newly diagnosed residents of Switzerland. Blood was anonymously collected from patients with a first confirmed positive HIV-1 test result. Viral DNA from the env V3-V5 region was amplified by nested polymerase chain reaction (PCR) and screened for subtype B by heteroduplex mobility assay. All amplicons not identified as B were sequenced. From November 1996 to February 1998, 206 samples were analyzed. Main transmission risks were unprotected heterosexual (55.7%) or homosexual (27.1%) sexual contact or intravenous drug use (12.9%). Subtype B dominated in patients of Swiss, other European, American, or Asian citizenship; particularly high frequencies were found in homosexuals (97%) and drug users (94%). Non-B subtypes including A, C, D, E, F, G, H, a possible B/F recombinant, and a sequence related to J were present in 28.2% (95% confidence interval [CI], 22.9%-35.0%). Non-B were frequent in African citizens (95%), heterosexually infected individuals (44%), and women (43%). Heterosexually infected Swiss males harbored non-B strains in 18% and females in 33%. The results document a change in the epidemiology of newly diagnosed HIV-1 infections in Switzerland: predominance of heterosexual transmission and a high frequency of non-B subtypes.

Assessment of Recent HIV-1 Infection by a Line Immunoassay for HIV-1/2 Confirmation

“…Like other European countries, Switzerland has a high rate of non-B infections [30] and the proportion of such viruses among newly diagnosed HIV-1 infections has now reached proportions of two-thirds in women and one-third in men (unpublished data from the Swiss genotypic resistance test database). Patients infected with such viruses may produce antibodies of reduced avidity to the subtype B antigens frequently employed in diagnostic tests, thus leading to low-reactivity patterns when tested and subsequent false diagnosis of recent infections.…”

Ambiguous Nucleotide Calls From Population-based Sequencing of HIV-1 are a Marker for Viral Diversity and the Age of Infection

“…Subtype B dominates the Swiss HIV-1 epidemic [10, 11], and we therefore focused on this subtype ( n  = 9,157 sequences). Because antiretroviral therapy strongly distorts viral diversity [12], we included only sequences from patients who were therapy-naïve at the time of sampling and for whom an independent estimate of infection time was available (3,307 sequences, each from a different patient).…”

Characteristics of Patients Recently Infected with HIV-1 Non-B Subtypes in France: a Nested Study within the Mandatory Notification System for New HIV Diagnoses

“…Subtype B predominates in the Americas, Europe, Japan, and Australia, whereas non-B subtypes predominate in Africa and in most Asian countries. Many studies have reported an increasing prevalence of non-B subtypes in Europe since the beginning of the epidemic (2)(3)(4)(5)(6)(7)(8)(9)(10). Whereas there is a common notion that HIV-1 infections with non-B subtypes are mainly associated with migrant populations from the developing world, there is increasing evidence that the epidemiology of non-B viruses in Europe results from both migration and domestic transmissions (11)(12)(13).…”

“…Whereas there is a common notion that HIV-1 infections with non-B subtypes are mainly associated with migrant populations from the developing world, there is increasing evidence that the epidemiology of non-B viruses in Europe results from both migration and domestic transmissions (11)(12)(13). Most of the studies have described the increasing prevalence of non-B variants in Europe among newly diagnosed HIV-1 infections or patients referred for antiretroviral resistance testing (4,(6)(7)(8)(9). However, the duration of infection for each new diagnosis was frequently unknown in these studies.…”