Persistence of human immunodeficiency virus in semen after adding indinavir to combination antiretroviral therapy

Considerations and development of topical microbicides to inhibit the sexual transmission of HIV

The increased incidence of HIV/AIDS disease in women aged 15 - 49 years has identified the urgent need for a female-controlled, efficacious and safe vaginal topical microbicide. To meet this challenge, new topical microbicide candidates consisting of molecules or formulations that modify the genital environment (BufferGel, engineered Lactobacillus, over-the-counter lubricants), surfactants (C31D/Savvy, sodium dodecyl sulfate, sodium lauryl sulfate), polyanionic polymers (PRO 2000, beta-cyclodextrin, Carraguard, CAP, D2S, SPL-7013), proteins (cyanovirin-N, monoclonal antibodies, thromspondin-1 peptides, Pokeweed antiviral protein and others), reverse transcription inhibitors (PMPA [Tenofovir ]), UC-781, SJ-3366, DABO and thiourea) and other molecules (NCp7-specific virucides, chemokine receptor agonists/antagonists, WHI-05 and WHI-07) are currently being investigated for activity, safety and efficacy. This review will assess the development of these molecules in the context of cervicovaginal defences and the clinical failure of nonoxynol-9.

Virologic and immunologic determinants of heterosexual transmission of human immunodeficiency virus type 1 in Africa

More than 80% of the world's HIV-infected adults live in sub-Saharan Africa, where heterosexual transmission is the predominant mode of spread. The virologic and immunologic correlates of female-to-male (FTM) and male-to-female (MTF) transmission are not well understood. A total of 1022 heterosexual couples with discordant HIV-1 serology results (one partner HIV infected, the other HIV uninfected) were enrolled in a prospective study in Lusaka, Zambia and monitored at 3-month intervals. A nested case-control design was used to compare 109 transmitters and 208 nontransmitting controls with respect to plasma HIV-1 RNA (viral load, VL), virus isolation, and CD4(+) cell levels. Median plasma VL was significantly higher in transmitters than nontransmitters (123,507 vs. 51,310 copies/ml, p < 0.001). In stratified multivariate Cox regression analyses, the risk ratio (RR) for FTM transmission was 7.6 (95% CI: 2.3, 25.5) for VL > or = 100,000 copies/ml and 4.1 (95% CI: 1.2, 14.1) for VL between 10,000 and 100,000 copies/ml compared with the reference group of <10,000 copies/ml. Corresponding RRs for MTF transmission were 2.1 and 1.2, respectively, with 95% CI both bounding 1. Only 3 of 41 (7%) female transmitters had VL < 10,000 copies/ml compared with 32 of 93 (34%) of female nontransmitters (p < 0.001). The transmission rate within couples was 7.7/100 person-years and did not differ from FTM (61/862 person-years) and MTF (81/978 person-years) transmission. We conclude that the association between increasing plasma viral load was strong for female to male transmission, but was only weakly predictive of male to female transmission in Zambian heterosexual couples. FTM and MTF transmission rates were similar. These data suggest gender-specific differences in the biology of heterosexual transmission.

Biologic approaches to the prevention of sexual transmission of human immunodeficiency virus

HIV prevention science has made progress, especially in Thailand and some sub-Saharan African countries. New cases of HIV in the United States, however, have not diminished and explosive epidemics in India and the People's Republic of China seem inevitable. Therefore, HIV prevention activities must move forward in parallel. Funding for biologic and behavioral research efforts must be balanced. Behavioral research must inform biologic strategies. In addition, HIV prevention efforts have been distorted by forces that require further consideration. First, the stigmatization associated with a diagnosis of HIV infection led to prevention efforts that virtually ignore the index case. Focusing entirely on the susceptible population puts intense and unrealistic pressure on behavior change and vaccine development. Although development of an HIV vaccine is desirable, there is no evidence that this goal can be achieved in the near future. Blind faith in vaccine technology detracts from pursuit of alternative aspects of prevention science. Vaccine development is but one of several key components to a broad-based prevention strategy. The history of control of infectious diseases has shown the need for targeting index cases. This certainly will prove important in HIV over the next few years. In developed countries, antiretroviral therapy for established HIV infection has become the standard of care. Increased knowledge of the biology of transmission of HIV suggests use of ART to prevent transmission. Such intervention must be accompanied by safer sex behavior in the index cases, and ultimately could lead to some form of monitoring and directly observed therapy. At this time, the latter approach seems unrealistic in developing countries, where the expense of drugs renders them unavailable. But there is every reason to believe that cheaper, more appropriate drugs will be developed before an effective vaccine. Furthermore, targeted use of ART might have disproportionate benefits in some countries. Women are the fastest growing HIV risk group. Several issues, both biologic and social, make this trend a concern. Increases in the number of HIV-infected women will lead to greater vertical transmission. Women possibly have different risk factors for acquisition and transmission than men. Information about the effects of vaginal ecology, specifically, the role of bacterial vaginosis, in the acquisition of HIV is essential because bacterial vaginosis can be reversed, at least transiently. To allow women to take an active role in HIV prevention methods, development of a topical microbicide is vital and may prove easier than a vaccine. Finally, HIV prevention efforts require knowledgeable, central leadership. All prevention efforts should be developed and implemented in parallel, to gain a synergistic result. Few vaccine experts are enthusiastic about microbicides, and HIV caregivers only rarely focus on the public health considerations of their patients. Stopping the spread of HIV requires a coordinated, concerted efforts using "all the tools in the toolbox."

Therapeutic targeting of human immunodeficiency virus type-1 latency: current clinical realities and future scientific possibilities

Factors affecting HIV-1 latency present formidable obstacles for therapeutic intervention. As these obstacles have become a clinical reality, even with the use of potent anti-retroviral regimens, the need for novel therapeutic strategies specifically targeting HIV-1 latency is evident. However, therapeutic targeting of HIV-1 latency requires an understanding of the mechanisms regulating viral quiescence and activation. These mechanisms have been partially delineated using chronically infected cell models and, clearly, HIV-1 activation from latency involves several key viral and cellular components. Among these distinctive therapeutic targets, cellular factors involved in HIV-1 transcription especially warrant further consideration for rational drug design. Exploring the scientific possibilities of new therapies targeting HIV-1 latency may hold new promise of eventual HIV-1 eradication.

Semen and serum pharmacokinetics of zidovudine and zidovudine-glucuronide in men with HIV-1 infection

STUDY OBJECTIVE

To characterize the concentration-time profiles of zidovudine and zidovudine-glucuronide in semen and serum of men infected with the human immunodeficiency-1 virus (HIV-1).

DESIGN

Open-label observational study.

SETTING

University-affiliated teaching hospital and research center.

PATIENTS

Four asymptomatic HIV-1-infected men.

INTERVENTIONS

Zidovudine administration was followed by an 8-hour intensive pharmacokinetic study on day 1. Over the next 8 days, a dose administration and timed single-sample strategy was employed to determine serum and semen concentration time profiles simultaneously.

MEASUREMENTS AND MAIN RESULTS

Zidovudine and zidovudine-glucuronide concentrations were uniformly higher in semen than in serum except at 1 hour after the dose. The median area under the curve ratio (semen AUC0-48:serum AUC0-infinity) was 3.31 for zidovudine and 15.04 for zidovudine-glucuronide.

CONCLUSION

Zidovudine and zidovudine-glucuronide reach high levels in seminal plasma relative to serum. The virologic, pharmacodynamic, and public health implications of distribution to this compartment require further study.

Incidence and impact of resistance against approved antiretroviral drugs

More than 15 antiretroviral drugs are now available for clinical use, and have led to significant reductions in morbidity and mortality for HIV infected individuals. Nevertheless, antiviral drug resistance emerges to all these drugs, which limits their benefit. This review addresses the biological basis of antiretroviral drug resistance, and the prevalence of specific drug resistance associated mutations in patients treated with the three currently available classes of agents, namely nucleoside analogue reverse transcriptase inhibitors, non nucleoside reverse transcriptase inhibitors and protease inhibitors. In addition, data on prevalence of HIV drug resistance in untreated individuals published to date are summarised, and the implications of potential transmission of drug resistant HIV is discussed.

Effect of highly active antiretroviral therapy on cervicovaginal HIV-1 RNA

OBJECTIVES

To determine the frequency of cervicovaginal lavage and plasma HIV-1 RNA levels that are below detectable levels (< 400 copies/ml) among women on highly active antiretroviral therapy (HAART), non-HAART and on no therapy. To compare the effect of initiating HAART on the timing of HIV-1 RNA suppression in the blood plasma and genital tract among antiretroviral-naïve women.

METHODS

Data were obtained from 205 HIV-infected women with paired plasma and cervicovaginal lavage viral load measurements. Seven antiretroviral-naïve women starting HAART had viral load measurements performed daily for one week, at 2 weeks and at 1 month after initiating therapy. Viral load quantification was carried out by nucleic acid sequence-based amplification assay. The lower limit of detection was 400 copies/ml.

RESULTS

Plasma and cervicovaginal HIV-1 RNA was detectable in 71 and 26% of the women, respectively. Among women with plasma viral loads less than 400, 400-9999, and 10,000 copies/ml or over, genital tract HIV-1 RNA was detected in 3, 17 and 48%, respectively (P < 0.001). Fifty-one per cent of the women with CD4 cell counts of less than 200/mm3 had detectable cervicovaginal viral loads compared with 18% among women with CD4 cell counts of 200/mm3 or over (P < 0.001). Cervicovaginal HIV-1 RNA was less than 400 copies/ml in 85% of those on HAART, 69% of those on non-HAART and 69% of those on no therapy (P < 0.045). In seven antiretroviral-naïve women initiating HAART, cervicovaginal HIV-1 RNA decreased by 0.7-2.1 log10 within 1-14 days of starting therapy.

CONCLUSION

The cervicovaginal HIV-1 RNA level was positively correlated with plasma HIV-1 RNA and negatively with the CD4 cell count. The use of HAART was significantly associated with below-detectable levels of HIV-1 RNA in both plasma and the genital tract. HIV-1 RNA suppression in the genital tract may occur rapidly after initiating therapy.

Human immunodeficiency virus type 1 cloning vectors for antiretroviral resistance testing

Better detection of minority human immunodeficiency virus type 1 (HIV-1) populations containing gene mutations may improve the usefulness of antiretroviral resistance testing for clinical management. Molecular cloning of HIV-1 PCR products which might improve minority detection can be slow and difficult, and commercially available recombinant virus assays test drug susceptibility of virus pools. We describe novel plasmids and simple methods for rapid cloning of HIV-1 PCR products from patient specimens and their application to generate infectious recombinant virus clones for virus phenotyping and genotyping. Eight plasmids with differing deletions of sequences encoding HIV-1 protease, reverse transcriptase, or Gag p7/p1 and Gag p1/p6 cleavage sites were constructed for cloning HIV-1 PCR products. A simple HIV-1 sequence-specific uracil deglycosylase-mediated cloning method with the vectors and primers designed here was more rapid than standard ligase-mediated cloning. Pooled and molecularly cloned infectious recombinant viruses were generated with these vectors. Replicative viral fitness and drug susceptibility phenotypes of cloned infectious viruses containing patient specimen-derived sequences were measured. Clonal resistance genotyping analyses were also performed from virus isolates, plasma HIV-1 RNA, and infected cell DNA. Sequencing of a limited number of molecular clones detected minorities of resistant virus not identified in the pooled population PCR product sequence and linkage of minority mutations.