Immunogenicity of a novel DNA vaccine cassette expressing multiple human immunodeficiency virus (HIV-1) accessory genes

Intervening in the HIV/AIDS Crisis: The Role of Black Psychologists

Over the prior 2 decades, HIV and AIDS have ravaged the Black community. This article summarizes the epidemiologic, social, and psychological impact of HIV/AIDS on individuals and affected subpopulations in the Black community. An overview is then provided of prevailing research on psychological and mental health issues in HIV/AIDS-related prevention and care that highlights key issues of concern to Black psychologists and areas in which Black psychologists are well positioned to make important contributions to the field. In conclusion, specific suggestions for Black psychologists to become more involved in work on HIV/AIDS are provided.

HIV Prevention Research for African Americans: Current and Future Directions

African Americans experience HIV and AIDS at a rate 10 times greater than the U.S. White population. Although there have been advances in HIV risk-reduction strategies, these efforts have not been as successful in decreasing HIV infection in the African American population. This article reviews the research base of HIV prevention interventions to identify research that will lead to the development of more effective prevention strategies for African Americans. Major limitations found in the research include the exclusion of African Americans in studies, particularly those at higher risk, and the lack of using culturally based theory to guide research. Recommendations for improving research are offered. They include conducting research that focuses on structural interventions rather than individuals, controlling for diversity within the African American population, defining culture when using it in research, and developing a cadre of African American researchers involved in prevention intervention studies.

Process evaluation of the Intervention with Microfinance for AIDS and Gender Equity (IMAGE) in rural South Africa

The Intervention with Microfinance for AIDS and Gender Equity (IMAGE) combines microfinance, gender/HIV training and community mobilization (CM) in South Africa. A trial found reduced intimate partner violence among clients but less evidence for impact on sexual behaviour among clients' households or communities. This process evaluation examined how feasible IMAGE was to deliver and how accessible and acceptable it was to intended beneficiaries during a trial and subsequent scale-up. Data came from attendance registers, financial records, observations, structured questionnaires (378) and focus group discussions and interviews (128) with clients and staff. Gender/HIV training and CM were managed initially by an academic unit ('linked' model) and later by the microfinance institution (MFI) ('parallel' model). Microfinance and gender/HIV training were feasible to deliver and accessible and acceptable to most clients. Though participation in CM was high for some clients, others experienced barriers to collective action, a finding which may help explain lack of intervention effects among household/community members. Delivery was feasible in the short term but both models were considered unsustainable in the longer term. A linked model involving a MFI and a non-academic partner agency may be more sustainable and is being tried. Feasible models for delivering microfinance and health promotion require further investigation.

Families, children, migration and AIDS

Migration is very often a family affair, and often involves children, directly or indirectly. It may give rise to better quality of life for an entire family, or to bitter disappointment, and may also increase vulnerability to HIV and AIDS. This review, carried out for the Joint Learning Initiative on Children and AIDS, links the literature on "migration", on "HIV and AIDS" and on "families". Three themes are sketched: (1) As both HIV prevalence and circular migration increase, former migrant workers affected by AIDS may return to their families for care and support, especially at the end of life, often under crisis conditions. Families thus lose promising members, as well as sources of support. However, very little is known about the children of such migrants. (2) Following patterns of migration established for far different reasons, children may have to relocate to different places, sometimes over long distances, if their AIDS-affected parents can no longer care for them. They face the same adaptation challenges as other children who move, but complicated by loss of parent(s), AIDS stigma, and often poverty. (3) The issue of migrant families living with HIV has been studied to some extent, but mainly in developed countries with a long history of migration, and with little attention paid to the children in such families. Difficulties include involuntary separation from family members, isolation and lack of support, disclosure and planning for children's care should the parent(s) die and differences in treatment access within the same family. Numerous research and policy gaps are defined regarding the three themes, and a call is made for thinking about migration, families and AIDS to go beyond description to include resilience theory, and to go beyond prevention to include care.

Comparison of immunogenicity, protective efficacy of single and cocktail DNA vaccine of Brugia malayi abundant larval transcript (ALT-2) and thioredoxin peroxidase (TPX) in mice

Although DNA vaccines have several advantages over conventional vaccines, antibody production and protection are often not adequate, particularly in single plasmid vaccine formulation. In the present study we evaluated the efficacy of a cocktail vaccine based on plasmids encoding larval (L3) stage-specific Brugia malayi abundant larval transcript (BmALT-2) and antioxidant detoxification enzyme B. malayi thioredoxin peroxidase (BmTPX) to induce antibodies, protective efficacy and cell-mediated immune response in mice. Mice immunized with cocktail DNA vaccines containing the pVAX ALT-2+TPX developed higher titers of anti-BmALT-2+TPX (1:5000) antibodies, compared to the mice immunized with single DNA vaccine of pVAX ALT-2 or pVAX TPX (1:2000). Correlating with this, the mice administered with cocktail vaccine induced up to 78% of cytotoxicity against B. malayi mf. This cytotoxicity was high compared to 34% induced by the pVAX-ALT2 or 37% by pVAX-TPX. Moreover, cocktail vaccination of mice resulted in significantly higher level of cellular proliferative response associated with raised levels of IFN-gamma that skewed towards Th1 type of response compared to vaccination using either of the components. Taken together, these data suggest that the combination of two or more antigens maybe an effective vaccine development strategy to improve protection and immunogenicity against human lymphatic filariasis.

HIV infection, sexual risk behavior, and substance use among Latino gay and bisexual men and transgender persons

OBJECTIVES

We examined HIV prevalence and the socioeconomic correlates of HIV infection, sexual risk behaviors, and substance use among Latino gay and bisexual men and transgender persons in Chicago and San Francisco.

METHODS

Data were collected from a sample of 643 individuals (Chicago: n=320; San Francisco: n=323) through respondent-driven sampling and computer-assisted self-administered interviews.

RESULTS

HIV prevalence in San Francisco (0.325; 95% confidence interval [CI]=0.260, 0.393) was higher than in Chicago (0.112; 95% CI=0.079, 0.163). In San Francisco, HIV prevalence was higher among US-born residents than among those born outside the country; in Chicago, the opposite was true. Heavy use of alcohol was prevalent, especially in Chicago (0.368; 95% CI=0.309, 0.432; San Francisco: 0.154; 95% CI=0.116, 0.192). Drug use and more education were positively correlated and greater age was negatively correlated with unprotected anal intercourse.

CONCLUSIONS

Heavy alcohol drinking and use of drugs remain a significant public health problem in this population. Drug use was more closely linked to HIV sexual risk behaviors than was heavy drinking.

Can variation in HIV/STD-related risk be explained by individual SES? Findings from female sex workers in a rural Chinese county

Low socioeconomic status (SES) has been linked to HIV and sexually transmitted disease (STD) at a macro level because the majority of new cases of HIV infection in the world have been reported in underdeveloped or developing countries. However, empirical data on the relationship between individual SES and HIV/STD related risk have been mixed. Employing quantitative data from 454 female sex workers (FSWs), this study was designed to examine the profile of the study sample in terms of their individual SES, HIV/STD-related sexual risk across work locations with different social, cultural, and economic conditions; and to examine the relationship between work location and HIV-related risk behaviors, controlling for individual SES. We have shown in the current study that both SES and HIV/STD-related risk behaviors significantly differed by work location. However, the difference in individual SES was not sufficient to explain the difference of HIV/STD-related risk across the work locations. The findings underscore the need for effective prevention intervention efforts targeting FSWs in rural areas. Based on the findings, we also suggest that HIV/STD intervention efforts among FSWs should take the social and cultural contextual factors of their working environment (and sexual risks) into consideration.

Therapeutic vaccination reduces HIV sequence variability

With HIV persisting lifelong in infected persons, therapeutic vaccination is a novel alternative concept to control virus replication. Even though CD8 and CD4 cell responses to such immunizations have been demonstrated, their effects on virus replication are still unclear. In view of this fact, we studied the impact of a therapeutic vaccination with HIV nef delivered by a recombinant modified vaccinia Ankara vector on viral diversity. We investigated HIV sequences derived from chronically infected persons before and after therapeutic vaccination. Before immunization the mean +/- se pairwise variability of patient-derived Nef protein sequences was 0.1527 +/- 0.0041. After vaccination the respective value was 0.1249 +/- 0.0042, resulting in a significant (P<0.0001) difference between the two time points. The genes vif and 5'gag tested in parallel and nef sequences in control persons yielded a constant amino acid sequence variation. The data presented suggest that Nef immunization induced a selective pressure, limiting HIV sequence variability. To our knowledge this is the first report directly linking therapeutic HIV vaccination to decreasing diversity in patient-derived virus isolates.

Sensitive oligonucleotide ligation assay for low-level detection of nevirapine resistance mutations in human immunodeficiency virus type 1 quasispecies

This study has adapted the oligonucleotide ligation assay (OLA) to probe for low-level nevirapine (NVP) resistance mutations K103N and Y181C in the human immunodeficiency virus type 1 (HIV-1) population of infected mother-infant pairs from Uganda. When NVP is used to prevent perinatal transmission, NVP-resistant HIV-1 clones may be rapidly selected due to a low barrier for mutation and a relatively high level of fitness (compared to that of other drug-resistant HIV-1 clones). Monitoring for even a low frequency of NVP resistance mutations may help predict the success of subsequent treatment or warrant the use of another regimen to prevent transmission in a subsequent pregnancy. The standard OLA was optimized by using nonstandard bases in oligonucleotides to allow promiscuous base pairing and accommodate significant HIV-1 heterogeneity. Radiolabeled as opposed to fluorescently tagged oligonucleotides increased the sensitivity, whereas alteration of the template, oligonucleotides, salt, and thermostable DNA ligase concentrations increased the specificity for the detection of minority codons. This modified OLA is now capable of detecting mutants with the K103N or the Y181C mutation present in an HIV-1 population at a frequency of approximately 0.4% and is at least 10- to 30-fold more sensitive than the original protocol. A cohort of 19 Ugandan mothers who received NVP treatment perinatally were sampled 6 weeks postdelivery. Ten of 19 HIV-1 DNA samples extracted from peripheral blood mononuclear cells had a detectable K103N (0.5 to 44%) or Y181C (0.8 to 92.5%) mutation, but only one plasma HIV-1 RNA sample had a viral population with the Y181C mutation. These findings suggest that OLA is a robust, sensitive, and specific method for the detection of low-frequency drug resistance mutations in an intrapatient HIV-1 population.

Using theory to understand how interventions work: Project RESPECT, condom use, and the Integrative Model

The Integrative Model of Behavioral Prediction (IM) provides guidelines for the development of successful HIV/STD interventions, yet few HIV prevention programs have identified which components of the IM have been associated with successful behavioral outcomes. Using structural equation modeling, this study examines in detail how components of the IM assessed prior to, and immediately after, the delivery of an intervention are associated with reported condom use 3 months later among participants in Project RESPECT, a multisite randomized controlled trial testing HIV/STD risk reduction strategies among clients attending public health clinics for sexually transmitted diseases. Overall, the IM predicted condom use at 3 months; there were, however, variations in the relative contribution of differing IM components as a function of gender and type of sexual partner as well as the type of intervention the participant had received.

Trends in primary and secondary syphilis among men who have sex with men in the United States

OBJECTIVES

We assessed the epidemiology of primary and secondary syphilis in the United States and estimated the percentages of cases occurring among men who have sex with men (MSM).

METHODS

We reviewed US syphilis surveillance data from 1990 through 2003. We estimated the number of cases occurring among MSM by modeling changes in the ratio of syphilis cases among men to cases among women.

RESULTS

During 1990 through 2000, the rate of primary and secondary syphilis decreased 90% overall, declining 90% among men and 89% among women. The overall rate increased 19% between 2000 and 2003, reflecting a 62% increase among men and a 53% decrease among women. In 2003, an estimated 62% of reported cases occurred among MSM.

CONCLUSIONS

Increasing syphilis cases among MSM account for most of the recent overall increase in rates and may be a harbinger of increasing rates of HIV infection among MSM. National efforts are under way to improve monitoring of syphilis trends, better understand factors associated with the observed increases, and improve efforts to prevent syphilis transmission.

Induction of human immunodeficiency virus type-1-specific immunity with a novel gene transport unit (GTU)-MultiHIV DNA vaccine

A multiHIV fusion gene expressing an antigenic fusion protein composed of regulatory HIV-1 proteins Rev, Nef, and Tat, as well as Gag p17/p24 and a stretch of 11 cytotoxic T lymphocyte (CTL) epitope clusters from Pol and Env, was cloned into a novel DNA vector named the Gene Transport Unit (GTU). A mouse H-2(d)-restricted HIV-1 gp120 epitope (RGPGRAFVTI) was cloned into the fusion gene as well. In addition to the HIV- 1 genes the GTU codes for a nuclear anchoring protein (bovine papilloma virus E2), ensuring the long maintenance of the vector and a high expression level of the selected immunogens. BALB/c mice were immunized with the GTU-MultiHIV DNA construct by different routes and regimens of immunization to assess the immunogenicity of the DNA vaccine in vivo. Mice developed strong CD8(+) CTL responses to HIV-1 Env and Gag measured by an ELISPOT-IFN-gamma assay and chromium release assay. In addition, T cell responses to regulatory proteins Rev, Nef, and Tat were induced. Antibody responses were detected to each of the HIV antigens encoded by the DNA construct. Minimal doses of the GTU-MultiHIV DNA delivered by gene gun were potent in inducing significant HIV-specific CTL responses. The equivalent doses of the conventional plasmid expressing MultiHIV DNA delivered by gene gun failed to do so. An ideal DNA vaccine should yield high expression of the viral antigens for a prolonged period of time, and expression of the multiple viral antigens is probably required for the induction of a broad and protective immune response. The GTU-MultiHIV DNA vaccine described is a good vaccine candidate that meets the above criteria.

Formaldehyde-treated, heat-inactivated virions with increased human immunodeficiency virus type 1 env can be used to induce high-titer neutralizing antibody responses

The lack of success of subunit human immunodeficiency virus (HIV) type 1 vaccines to date suggests that multiple components or a complex virion structure may be required. We hypothesized that the failure of current vaccine strategies to induce protective antibodies is linked to the inability of native envelope structures to readily elicit these types of antibodies. We have previously reported on the ability of a formaldehyde-treated, heat-inactivated vaccine to induce modest antibody responses in animal vaccine models. We investigated here whether immunization for HIV with an envelope-modified, formaldehyde-stabilized, heat-inactivated virion vaccine could produce higher-titer and/or broader neutralizing antibody responses. Thus, a clade B vaccine which contains a single point mutation in gp41 (Y706C) that results in increased incorporation of oligomeric Env into virions was constructed. This vaccine was capable of inducing high-titer antibodies that could neutralize heterologous viruses, including those of clades A and C. These results further support the development of HIV vaccines with modifications in native Env structures for the induction of neutralizing antibody responses.

Genetic immunization with multiple HIV-1 genes provides protection against HIV-1/MuLV pseudovirus challenge in vivo

Superinfection by HIV-1 of a cell line containing the complete murine leukemia virus (MuLV) genome was shown to give rise to pseudotyped HIV-1/MuLV. Such superinfection was successful with certain strains of HIV-1 subtypes A-D. Primary spleen cells and cells of the peritoneal cavity of immunocompetent mice of the C57Bl/6 strain were infectable with the pseudotype HIV-1/MuLV and secreted HIV-1 in vitro and in vivo. In contrast, the murine cell lines, NIH 3T3, myeloma cell line Sp2/0, and two murine hybridoma cell lines were relatively resistant to infection and produced no or little HIV. After primary murine spleen cells had been infected with pseudotyped HIV-1 and transferred to C57Bl/6 mice, replication-competent HIV-1 was obtained from the peritoneal cavity for at least 10-14 days. High amounts (> 10(5) vRNA copies/ml) of HIV-1 vRNA could be measured in the peritoneal fluid. Presence of HIV-1 proviral DNA was detectable in cells from the peritoneal cavity for up to 24 days after infected cell transfer. Active reverse transcriptase representing both HIV-1 and C-type murine retroviruses was detected in the peritoneal washes. The HIV-infected spleen cells injected into the peritoneal cavity elicited HIV-1-specific cellular immune responses to p24gag, gp160Env, Nef, Tat and Rev. Mice immunized with HIV-1 DNA, but not with HIV-1 protein, cleared their HIV-1-infected cells within 10-14 days after challenge with HIV-1/MuLV-infected syngeneic spleen cells. This novel model system of primarily cellular reactivity to HIV-1-infected cells in vivo may become useful for assaying experimental HIV-1 immunization schedules.

Nonstructural HIV proteins as targets for prophylactic or therapeutic vaccines

By the end of 2004, more than 20 HIV-1 vaccine candidates will have entered clinical testing in at least 30 trials worldwide. Almost half of these vaccines include nonstructural HIV-1 gene products. This represents an important innovation in the HIV vaccine field, because until 9 years ago not even preclinical testing in small animal models had been carried out with such immunogens. This review briefly discusses the experimental evidence that provides the rationale for the use of nonstructural HIV-1 gene products as vaccine antigens, and summarizes the current status and the future development of these novel vaccines.

Topical delivery of imiquimod to a mouse model as a novel adjuvant for human immunodeficiency virus (HIV) DNA

We evaluated the compound imiquimod as a possible adjuvant for DNA immunization against human immunodeficiency virus (HIV). We found that gene-gun epidermal delivery of the DNA in combination with imiquimod resulted in the strongest HIV specific immune responses. The effect of imiquimod was further compared to that of recombinant granulocyte macrophage-colony stimulating factor (GM-CSF), a known DNA vaccine adjuvant. Both adjuvants were able to enhance the immune responses induced by the HIV-1 genes alone. The delivery of an adjuvant as a topical cream rather than through injections has a clear clinical benefit. We show for the first time that imiquimod can act as an adjuvant for DNA vaccination.

Competitive fitness of nevirapine-resistant human immunodeficiency virus type 1 mutants

Determining the fitness of drug-resistant human immunodeficiency virus type 1 (HIV-1) strains is necessary for the development of population-based studies of resistance patterns. For this purpose, we have developed a reproducible, systematic assay to determine the competitive fitness of HIV-1 drug-resistant mutants. To demonstrate the applicability of this assay, we tested the fitness of the five most common nevirapine-resistant mutants (103N, 106A, 181C, 188C, and 190A), with mutations in HIV-1 reverse transcriptase (RT), singly and in combination (for a total of 31 variants) in a defined HIV-1 background. For these experiments, the 27 RT variants that produced viable virus were cocultured with wild-type virus without nevirapine. The ratios of the viral species were determined over time by utilization of a quantitative real-time RT-PCR-based assay. These experiments revealed that all of the viable variants were less fit than the wild type and demonstrated that the order of relative fitness of the single mutants tested was as follows: 103N > 181C > 190A > 188C > 106A. This order correlated with the commonality of these mutants as a result of nevirapine monotherapy. These investigations also revealed that, on average, the double mutants were less fit than the single mutants and the triple mutants were less fit than the double mutants. However, the fitness of the single and double mutants was often not predictive of the fitness of the derivative triple mutants, suggesting the presence of complex interactions between the closely aligned residues that confer nevirapine resistance. This complexity was also evident from the observation that all three of the replication-competent quadruple mutants were fitter than most of the triple mutants, and in some cases, even the double mutants. Our data suggest that, in many cases, viral fitness is the determining factor in the evolution of nevirapine-resistant mutants in vivo, that interactions between the residues that confer nevirapine resistance are complex, and that these interactions substantially affect reverse transcriptase structure and/or function.

HIV Prevention Research: Are We Meeting the Needs of African American Men Who Have Sex With Men?

Two decades of HIV prevention efforts with men who have sex with men (MSM) have not eliminated the risk of new HIV infections in this vulnerable population. Indeed, current incidence rates in African American MSM are similar to those usually only seen in developing countries. A review of the existing literature suggests that the prevention research agenda for Black MSM could benefit from reframing conceptualization of risk as a function of individual properties to a broad consideration of social and interpersonal determinants. Studies that investigate dyadic and social-level influences on African American MSM's relationships are needed. This includes research explicating the diversity existing within the categorizations of Black MSM with respect to perceived identity (gay, bisexual, "men on the down low," "homo thugz"), constructions of masculinity, sexual scripts, sources of social support, and perceived norms and expectations. Recommendations are proposed for a research agenda focusing on linkages between interpersonal and social-structural determinants of HIV risk.

Interruption of nonnucleoside reverse transcriptase inhibitor (NNRTI) therapy for 2 months has no effect on levels of human immunodeficiency virus type 1 in plasma of patients harboring viruses with mutations associated with resistance to NNRTIs

A 2-month interruption of only nonnucleoside reverse transcriptase inhibitors (NNRTIs) for patients carrying mutations associated with resistance to NNRTIs was followed by no change in either viral load or CD4 cell counts. These data suggest that these compounds have lost all of their in vivo antiviral activity in such cases.

Greater reversal of CD4+ cell abnormalities and viral load reduction after initiation of antiretroviral therapy with zidovudine, lamivudine, and nelfinavir before complete HIV type 1 seroconversion

In a prospective open-label study, 41 male subjects received nelfinavir, zidovudine, and lamivudine stratified as either: early stage (ES; negative/indeterminate Western blot; n = 19) or late stage (LS; positive Western blot; n = 22) primary HIV-1 infection. Despite higher median baseline HIV-1 RNA levels and lower CD4(+) cell numbers in the ES subjects, a significantly greater decline in viral load (-3.46 vs. -2.83 log(10) copies/ml; p = 0.023) and increase in CD4(+) cell number (+85 vs. +41 cells/month increase, p = 0.01) were observed over the first 3 months of therapy such that both groups had comparable results at 1 year. The proportion with HIV-1 RNA < 50 copies/mL at 1 year was similar (9 of 19 ES subjects and 11 of 22 LS subjects by intention-to-treat analysis). Memory CD4(+) cell numbers, and activated CD4(+) percentages, were also significantly improved in ES subjects. Despite poorer prognostic markers at baseline ES subjects achieved responses similar to those of LS subjects after 1 year of treatment.

Comparing sexual behavioral patterns between two bathhouses: implications for HIV prevention intervention policy

There is a glaring lack of data to inform culturally appropriate HIV prevention interventions targeting environments such as bathhouses where men who have sex with men (MSM) practice sexual risk behaviors. This study compares sexual behavioral patterns across two bathhouse sites in order to identify important themes to address when tailoring HIV prevention interventions to bathhouse environments. We analyzed semi-structured interviews with workers and patrons at two bathhouses to explore similarities and differences. A coding scheme was established and data were organized according to conceptual themes. We found that differences between the two sites emerged in six key areas: bathhouse clientele, attraction to particular sites, sexual practices and condom use, communication about sex and HIV status, bathhouse rules, and substance use. Implications for HIV prevention intervention policy are discussed.

Inclusion of Vpr accessory gene in a plasmid vaccine cocktail markedly reduces Nef vaccine effectiveness in vivo resulting in CD4 cell loss and increased viral loads in rhesus macaques

We compared the immunogenicity of plasmid vaccines containing multiple human immunodeficiency virus (HIV) antigens and found that covaccination with plasmids expressing HIV-1 14 kDa vpr gene product profoundly reduces antigen-specific CD8-mediated cytotoxic T-cell activity (CTL). Interestingly, Th1 type responses against codelivered antigens (pGag-Pol, pNef, etc.) encoded by the plasmid vaccines were suppressed. This suggested that vpr might compromise CD8 T-cell immunity in vivo during infection. A pilot primate vaccine study was designed to test the hypothesis to compare the following groups: unvaccinated controls, animals vaccinated without simean immunodeficiency virus (SIV)-Nef antigen plasmid, and animals covaccinated with the identical plasmid antigen and a plasmid construct encoding SIV Vpr/Vpx. Animals were subsequently challenged intrarectally with pathogenic SIVmac251 after the final vaccination of a multiple immunization protocol. Control animals were all infected and exhibited high viral loads and rapid CD4+ T-cell loss. In contrast, the Nef plasmid-vaccinated animals were also infected but exhibited preservation of CD4+ T-cells and a multilog reduction in viral load compared with controls. Animals covaccinated multiple times with the Nef vaccine and pVpr/Vpx plasmid suffered rapid and profound loss of CD4+ T-cells. These results have important implications for the design of multicomponent and particle vaccines for HIV-1 as well as for our understanding of HIV/SIV pathogenesis in vivo.

A mutation in the 3' region of the human immunodeficiency virus type 1 reverse transcriptase (Y318F) associated with nonnucleoside reverse transcriptase inhibitor resistance

The Y318F substitution in the 3' region of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) has been linked to nonnucleoside RT inhibitor (NNRTI) resistance in vitro. A systematic search of a large phenotypic-genotypic database (Virco) linked the Y318F substitution with a >10-fold decrease in NNRTI susceptibility in >85% of clinically derived isolates. There was a significant association between Y318F and use of delavirdine (P = 10(-11)) and nevirapine (P = 10(-6)) but not efavirenz (P = 0.3). Site-directed HIV-1 Y318F mutants in an HXB2 background displayed 42-fold-decreased susceptibility to delavirdine but <3-fold-decreased susceptibility to nevirapine or efavirenz. Combinations of Y318F with K103N, Y181C, or both resulted in decreased efavirenz susceptibility of 43-, 3.3-, and 84-fold, respectively, as well as >100- and >60-fold decreases in delavirdine and nevirapine susceptibility, respectively. These results indicate the importance of the Y318F substitution in HIV-1 drug resistance.

Issues for improving multiplasmid DNA vaccines for HIV-1

Since the first reports of plasmid vaccines, there have been substantial changes made to the design of plasmid backbones, as well as to the antibiotic resistance markers chosen for clinical vectors compared with first generation vectors. These changes aid manufacturing, production and scale up and at the same time aid conceptual safety by limiting the ability of the vaccines to transfer useful genetic selection genes to other bacterial infectious agents. In contrast, there has been little change to the original promoters or polyadenlyation tracts in the last decade. We have learned that these first generation plasmid vaccines for HIV-1 appear very well tolerated in humans. However, while safe and immunogenic, improving the immune potency of DNA vaccines is a critical goal for this technology. The combination of antigens used should be carefully examined for possible immune interference. Such interference may only become apparent when each component of the vaccine is tested individually. This interference also suggests one mechanism of immune pathogenesis possibly by HIV-1. Optimization of the immune response can come through manipulation of the transfection efficiency, expression or through the use of various T cell and B cell plasmid adjuvants. It is likely that the combination of such advancements will significantly improve the clinical phenotype of this important vaccine modality.

Genotypic testing for human immunodeficiency virus type 1 drug resistance

There are 16 approved human immunodeficiency virus type 1 (HIV-1) drugs belonging to three mechanistic classes: protease inhibitors, nucleoside and nucleotide reverse transcriptase (RT) inhibitors, and nonnucleoside RT inhibitors. HIV-1 resistance to these drugs is caused by mutations in the protease and RT enzymes, the molecular targets of these drugs. Drug resistance mutations arise most often in treated individuals, resulting from selective drug pressure in the presence of incompletely suppressed virus replication. HIV-1 isolates with drug resistance mutations, however, may also be transmitted to newly infected individuals. Three expert panels have recommended that HIV-1 protease and RT susceptibility testing should be used to help select HIV drug therapy. Although genotypic testing is more complex than typical antimicrobial susceptibility tests, there is a rich literature supporting the prognostic value of HIV-1 protease and RT mutations. This review describes the genetic mechanisms of HIV-1 drug resistance and summarizes published data linking individual RT and protease mutations to in vitro and in vivo resistance to the currently available HIV drugs.

Next generation DNA vaccines for HIV-1

We studied the effects of first generation HIV-1 plasmid vaccines in 167 individuals. The vaccines were very well tolerated and induced helper T cell responses in most vaccine recipients. However, the CTL responses were below a 20% response rate. Improvement in vaccine potency is an important goal of this technology and a central focus of our laboratory. To improve on these response rates, we used RNA optimized constructs pGag and pEnv). These vaccines express 20-100 fold better than first generation vectors. However, our studies support that additional enhancements are needed to further boost the immune response. We report that we can significantly enhance the induced CD8 effector cell response by including engineered B7 costimulatory molecules. We observed that B7.2 was more effective at driving cellular immune responses than B7.1 as a plasmid vaccine. We developed gene swaps and deletions between these two molecules. This manipulation resulted in a dramatically enhanced cellular immune response as measured by CTL, or ICC or Elispot. We have also explored the use of cytokines as plasmid vaccine adjuvants. We observed that IL-12 and IL-15 were effective as plasmid vaccine adjuvants. Interestingly, IL-15 appeared to allow T cell expansion in the absence of significant T cell help. Improvement of the immune response induced by plasmid vaccines can be engineered in multiple ways. Our studies show that both costimulation as well as cytokine signals can be harnessed for more potent vaccine development. These results have important implications for the design of vaccines for prophylaxis and therapy.

Different degree of immune recovery using antiretroviral regimens with protease inhibitors or non-nucleosides

BACKGROUND

Protease inhibitors (PI) produce significant immune recovery in most HIV-infected persons, although toxicity and high pill burden often limit this benefit. Combinations including non-nucleoside reverse transcriptase inhibitors (NNRTI) result in similar virological success, but data on immune reconstitution are scarce.

METHODS

Baseline plasma viraemia and CD4 cell counts were recorded from 100 patients who began two nucleoside analogue reverse transcriptase inhibitors plus either one PI or one NNRTI in a case-control study [indinavir (82%) and nevirapine (80%), respectively, were most frequently prescribed]. Only patients with baseline CD4 cell counts < 500 x 10(6) cells/l, good treatment adherence and plasma HIV RNA < 50 copies/ml sustained for 1 year were recruited.

RESULTS

A rapid CD4 cell gain occurred within 12 weeks on therapy (average 41.8 x 10(6) cells/l per month), irrespective of treatment. In contrast, a trend towards a better CD4 cell gain was noticed between 12 and 48 weeks with a PI (mean CD4 cell increases per month: 15.2 x 10(6) cells/l using PI and 10.4 x 10(6) cells/l using NNRTI). During this period, the difference between therapy with a PI and a NNRTI reached statistical significance for subjects with baseline CD4 counts < 300 x 10(6) cells/l (17.1 x 10(6) and 6.4 x 10(6) cells/l, respectively; P < 0.05).

CONCLUSION

A rapid CD4 cell increase occurred shortly after beginning antiretroviral therapy using either PI or NNRTI. Late increases in CD4 cell counts, mostly owing to newly produced cells rather than redistribution, are more pronounced in therapy using a PI, especially in subjects with lower initial CD4 cell counts.

The basis for HIV immunotherapeutic vaccines

The drug treatments introduced in recent years for HIV infection have enabled a marked reduction in morbidity and prolongation of life. These treatments, however, are often associated with acute and chronic toxicities, the development of resistant virus can limit their effectiveness, and they are too expensive and difficult to administer in most third world settings. A successful HIV immunotherapeutic vaccine has the potential to overcome these problems, and would be a valuable advance. The most promising approaches have induced the type of immune response found to correlate with reduced activity of HIV in man, especially cytotoxic T-cell responses, or have led to reduced HIV or SIV viral load and increased CD4 counts in non-human primates or man. The agents that have led to one or both of these effects have been selected for review, and include inactivated envelope depleted virus, recombinant envelope glycoprotein, DNA vaccines utilising HIV peptides or gene products, viral vectors, such as canarypox or attenuated vaccinia, with HIV core proteins. There are other approaches, such as alloimmunity, for which no candidate products yet exist, but which conceptually appear promising. Currently, however, only a few phase III studies of HIV therapeutic vaccines have been completed in man, and there has been a modest therapeutic effect. Further development of both existing and new candidates remains one of the key priorities in our fight against HIV.

Rational development of prophylactic HIV vaccines based on structural and regulatory proteins

The severity of the AIDS epidemic clearly emphasises the urgent need to expedite HIV vaccine candidates into clinical trials. Prophylactic HIV vaccine candidates have been evaluated in non-human primates. Based on specific proof of principle studies the first phase III clinical studies have recently begun in humans. However, a truly effective HIV vaccine is not yet at hand and many problems related to specific properties of the virus remain to be overcome. Previously proven empirical approaches have largely failed and now rational thinking based on an understanding of immunity to lentiviral infections is needed. This review addresses the scientific problems and complications facing the development of an HIV vaccine as well as the possible strategies currently available to overcome these problems. Recent attention has focussed on identifying the immune correlates and mechanisms of protection from either HIV infection or protection from disease progression. Based on these observations, the logic and rational behind the development of multiple component vaccine strategies are highlighted.

Interactions of single and combined human immunodeficiency virus type 1 (HIV-1) DNA vaccines

DNA immunization permits evaluation of possible antagonistic or synergistic effects between the encoded components. The protein expression capacity in vitro was related to the immunogenicity in vivo of plasmids encoding the HIV-1 regulatory genes tat rev, and nef. Neither Tat nor Rev expression was influenced by co-expression in vitro of all three proteins, while Nef expression was slightly inhibited. With the combination of genes, the T-cellular responses of mice against Rev and Nef were inhibited compared with those when single gene immunization was used. No interference was detected for the Tat T-cell response. Thus, co-immunization with certain genes may result in inhibition of specific immune responses.

Clinical and laboratory guidelines for the use of HIV-1 drug resistance testing as part of treatment management: recommendations for the European setting. The EuroGUidelines Group for HIV resistance

Viral drug susceptibility is associated with virologic response to new treatments. Standardized drug resistance tests are now available, and data from some clinical trials suggest that the use of drug resistance testing may be associated with improved virologic outcome. However, drug resistance testing is complex in terms of performance, interpretation and clinical application. HIV-1 drug resistance testing is used across Europe in patient management, but not in a consistent manner. This is due to differences in the national approaches to treatment, treatment management and reimbursement, as well as availability of tests. National guidelines only exist in some countries. In addition, the laboratory quality assurance and quality control standards are not applied uniformly. The EuroGuidelines Group was established to formulate clinical as well as laboratory guidelines for the use of HIV-1 drug resistance testing that are specific for the European setting. The group is comprised of academic clinicians and virologists, scientist from the industry and representatives of the patient community. The panel of experts will review these guidelines and update them on a yearly basis as new scientific evidence becomes available.