Therapeutic vaccination in primary HIV infection, the Quest trial

Cognitive factors and willingness to participate in an HIV vaccine trial among HIV-positive injection drug users

There are gaps in our knowledge of the role cognitive factors play in determining people's willingness to participate (WTP) in therapeutic HIV vaccine trials. Using a cross-sectional study of HIV-positive injection drug users (IDU), we determined the role of three cognitive factors: HIV treatment optimism, self-efficacy beliefs, and knowledge of vaccine trial concepts in relation to WTP in a hypothetical phase 3 therapeutic HIV vaccine trial. WTP was 54%. Participants tended to be low in HIV treatment optimism (mean = 3.9/10), high in self-efficacy (mean = 79.8/100), and low in knowledge (mean = 4.1/10). Items pertaining to HIV treatment optimism and knowledge of HIV vaccine trial concepts were generally unrelated to WTP. An increase in self-efficacy had a statistically significant positive association with WTP (OR = 1.61, 95% CI = 1.04-2.46, p < 0.05). Furthermore, most of these HIV-positive participants had high levels of self-efficacy, so we are most confident about this relationship at such levels. These findings indicate that interventions focused on increasing self-efficacy could enhance WTP among HIV-positive IDU.

Early induction of leukemia inhibitor factor (LIF) in acute HIV-1 infection

BACKGROUND

Leukemia inhibitor factor (LIF) is thought to play a substantial role in protecting CD4 T cells in lymphoid tissues (LT) from infection by HIV-1.

OBJECTIVE

To investigate whether primary HIV-1 infected subjects with sustained virological control (< 1000 HIV-1 RNA copies/ml plasma) post-cessation antiretroviral therapy (ART) had a higher initial LIF response during primary HIV-1 infection (PHI) as compared with those individuals who did not achieve a similar control (> 9000 HIV-1 RNA copies/ml plasma) of HIV-1 replication.

MATERIAL AND METHODS

Consecutively obtained HIV plasma samples were collected from primary HIV-1 infected subjects. A group of acutely Epstein-Barr virus-infected subjects and a group of HIV-1-seronegative healthy individuals served as controls. All samples were tested by ELISA for LIF and sgp130, the soluble form of LIF's signalling receptor.

RESULTS

LIF and sgp130 plasma levels were significantly increased in primary HIV-1-infected subjects as compared with HIV-1-seronegative controls. Peak plasma levels of LIF occurred during the first week of PHI whereas sgp130 peaked between 2 and 4 weeks after the onset of PHI. Furthermore a positive correlation was found between viral load and plasma levels of LIF during PHI. Both LIF and sgp130 plasma concentrations were significantly lower during the viral rebound phase after treatment interruption as compared with the PHI phase.

CONCLUSIONS

LIF induction occurred in the initial stages of viral dissemination during PHI. It may be a part of the virally induced generalized pro-inflammatory response. LIF levels at PHI did not predict low levels of HIV viraemia after discontinuation of ART. LIF was not increased following ART interruption in this early treated population.

Therapeutic vaccination against HIV: current progress and future possibilities

Although effective in reducing mortality, current antiretroviral therapy for HIV infection involves complex and expensive drug regimens that are toxic and difficult to take. Eradication of HIV reservoirs is not possible with existing therapies. The concept of therapeutic vaccination has been investigated to increase the potency and breadth of anti-HIV immune responses in order to delay or reduce antiretroviral therapy use. A variety of approaches targeted to both cell- and antibody-mediated immunity have been developed, including whole inactivated HIV-1, protein subunits and synthetic peptides, DNA vaccines and a number of viral vectors expressing HIV-1. These investigations have occurred in the absence of a clear understanding of disease pathogenesis or the correlates of protective immunity. At this time, there is no licensed therapeutic vaccine for any viral disease, including HIV; however, this review will consider recent progress in the field and summarize the challenges faced in the development of a therapeutic HIV vaccine.

The potential role of the HIV-1 immunogen (Remune) as a therapeutic vaccine in the treatment of HIV infection

Immune-based therapies, such as therapeutic vaccination, that might preserve, restore, enhance and induce new HIV-specific immunologic responses are currently being explored. HIV-specific immunotherapy with Remune (The Immune Response Corp.) offers the opportunity to boost immune responses against HIV-1. The clinical trial program in a wide range of subjects has established the efficacy of Remune in stimulating an appropriate immune response in HIV-positive individuals. Furthermore, a recent unblinded study conducted in Europe has documented a significant effect of Remune on viral load. Evidence regarding clinical end points is more difficult to collect. The same studies have revealed no serious safety issues in a total of more than 2000 Remune-treated patients. It is therefore reasonable to suggest that the risk-benefit ratio of Remune could be positive.

Frequent detection of acute primary HIV infection in men in Malawi

BACKGROUND

Acute (antibody-negative) HIV infection is associated with high transmission potential but is rarely recognized.

DESIGN

Cross-sectional study.

METHODS

We examined the prevalence and predictors of acute HIV infection among 1361 consecutive male outpatients attending sexually transmitted disease (STD; n = 929) and dermatology (n = 432) clinics in Lilongwe, Malawi. Serum specimens negative for HIV antibodies were screened by HIV RNA PCR using a highly specific pooling/resolution testing algorithm.

RESULTS

Five-hundred and fifty-three men (40.6%) were HIV antibody positive and 24 (1.8%) had acute HIV infection; 23 of 24 acutely infected men were from the STD clinic, where they represented 4.5% of all HIV antibody-negative men and 5.0% of all HIV infections. HIV RNA levels for acutely infected men were significantly higher [median (interquartile range), 6.10 (5.19-6.54) log10 HIV RNA copies/ml] than for 58 HIV antibody-positive men [4.42 (3.91-4.95) log10 copies/ml; P < 0.0001]. The factor most strongly associated with acute HIV infection was STD clinic attendance: (odds ratio, 15.2; 95% confidence interval, 2.04-113.0). In multivariate analysis considering only STD patients, factors associated with acute HIV infection included inguinal adenopathy, genital ulceration and age 24-26 years, the age stratum associated with peak incidence of HIV infection among Malawian men.

CONCLUSIONS

Traditional HIV antibody tests alone are not sufficient to exclude HIV infection among men with acute STD in Malawi due to a surprising proportion of acute HIV infections in this population. Alternative screening methods are required for diagnosis of acute HIV infection; such screening could be important for research and for prevention of the sexual transmission of HIV in select populations.

Therapeutic vaccines against infectious diseases

Therapeutic vaccines against chronic infectious diseases aim at eliciting broad humoral and cellular immune responses against multiple target antigens. Importantly, the development of such vaccines will help to establish surrogate markers of protection in humans and thus will augment the subsequent development of efficient prophylactic vaccines. A combination of synthetic small-molecule drugs and immunotherapeutics is likely to represent a powerful means of controlling chronic infections in the future. Challenges faced in developing therapeutic vaccines include the following: first, overcoming the potential impairment of immune responses due to established infection; second, optimizing schedules of vaccine administration in combination with standard of care chemotherapy; and third, defining what biological and immunological read-outs should be used to infer vaccine efficacy.