Report may lead to population collection by the back door

Transmitted drug-resistant HIV-1 in primary HIV-1 infection; incidence, evolution and impact on response to antiretroviral therapy

OBJECTIVES

The aim of the study was to determine the incidence and persistence of transmitted drug-resistant HIV-1 in an incident cohort between 2000 and 2004, and to investigate the impact of transmitted drug-resistant HIV-1 on the response to antiretroviral therapy (ART).

METHODS

A prospective, nonrandomized study was carried out on 140 individuals identified with primary HIV-1 infection (PHI). PHI was defined as an HIV-positive antibody test with an HIV antibody-negative result in the prior 6 months (n = 69); positive HIV DNA in the absence of antibody (n = 30); an evolving titre positive HIV antibody test (n = 23), or an incident 'detuned' assay (B clade viruses only) (n = 18). Genotypic resistance testing was performed at baseline, following ART and annually over a 4-year period.

RESULTS

The prevalence of transmitted drug-resistant HIV-1 infection between January 2000 and June 2004 was nine in 140 (6.0%) and the annual incidence was stable. Seven of these nine patients had a single point mutation conferring single-class drug resistance and the other two patients had multiple mutations conferring multiclass drug resistance (MDR). In eight of the nine cases, mutations conferring drug resistance persisted for more than 12 months off therapy. In contrast to transmitted MDR HIV-1, the virological response to initial ART and CD4 decline were comparable in those with wild-type virus, virus with 'polymorphisms' (secondary mutations) and virus with single drug-resistance mutations.

CONCLUSIONS

The incidence of transmitted drug-resistant HIV remained stable and low over a 4-year period. Although MDR remains rare, its presence significantly affects the response to first-line ART, predisposes towards the accumulation of new resistance mutations and is associated with a more rapid CD4 decline.

The global status of resistance to antiretroviral drugs

Since 1989, the emergence of resistant human immunodeficiency virus mutants has been documented for any new antiretroviral agent introduced in the clinical setting; it is a major cause of failure of antiretroviral therapy that may ultimately compromise the antiretroviral's efficacy in the general population. In most cases, resistance is due to poor adherence by the patient and/or to low potency of the therapeutic regimen. Resistance is called "primary" if detected in treatment-naive persons and is called "acquired" when it develops in treatment-experienced persons. This latter population represents potential transmitters of resistant viruses to newly infected persons. Data about the actual prevalence of resistance are derived from studies that differ in design, sample size, geographic area, and definitions. For this reason, a limited number of surveillance programs have been established in the past, both in countries where highly active antiretroviral therapy is widely accessible and in geographic areas where it is being introduced.

HIV: epidemiology and strategies for therapy and vaccination

In the decades since its discovery, the acquired immunodeficiency syndrome AIDS has developed into one of the leading causes of death worldwide, with a dramatic situation in many countries of subsaharan Africa. A large body of knowledge has been acquired regarding the molecular biology and replication properties of the causative agent of AIDS, the human immunodeficiency virus (HIV). However, despite these advances the global spread of HIV and especially its spread in developing countries continues almost unabated. During the last decade, drugs inhibiting HIV replication have been introduced into clinical use and highly active antiretroviral therapy (HAART) using a combination of several drugs has been proven to slow or halt the course of the disease in most patients. However, HAART is currently only available in countries of the developed world and the emergence of resistant variants may rapidly lead to a partial loss of this therapeutic arsenal. Thus, the development of a prophylactic vaccine against HIV must be the ultimate goal to control the global pandemic of AIDS. This minireview summarises the state of the epidemic and discusses current treatment strategies as well as future developments. Finally, strategies towards the development of a vaccine against HIV are presented and recent studies using prime-boost regimens to achieve protection from disease in animal models while not preventing infection with the challenge virus are discussed.