Genetic Diversity and Protective Efficacy of the RTS,S/AS01 Malaria Vaccine

BACKGROUND

The RTS,S/AS01 vaccine targets the circumsporozoite protein of Plasmodium falciparum and has partial protective efficacy against clinical and severe malaria disease in infants and children. We investigated whether the vaccine efficacy was specific to certain parasite genotypes at the circumsporozoite protein locus.

METHODS

We used polymerase chain reaction-based next-generation sequencing of DNA extracted from samples from 4985 participants to survey circumsporozoite protein polymorphisms. We evaluated the effect that polymorphic positions and haplotypic regions within the circumsporozoite protein had on vaccine efficacy against first episodes of clinical malaria within 1 year after vaccination.

RESULTS

In the per-protocol group of 4577 RTS,S/AS01-vaccinated participants and 2335 control-vaccinated participants who were 5 to 17 months of age, the 1-year cumulative vaccine efficacy was 50.3% (95% confidence interval [CI], 34.6 to 62.3) against clinical malaria in which parasites matched the vaccine in the entire circumsporozoite protein C-terminal (139 infections), as compared with 33.4% (95% CI, 29.3 to 37.2) against mismatched malaria (1951 infections) (P=0.04 for differential vaccine efficacy). The vaccine efficacy based on the hazard ratio was 62.7% (95% CI, 51.6 to 71.3) against matched infections versus 54.2% (95% CI, 49.9 to 58.1) against mismatched infections (P=0.06). In the group of infants 6 to 12 weeks of age, there was no evidence of differential allele-specific vaccine efficacy.

CONCLUSIONS

These results suggest that among children 5 to 17 months of age, the RTS,S vaccine has greater activity against malaria parasites with the matched circumsporozoite protein allele than against mismatched malaria. The overall vaccine efficacy in this age category will depend on the proportion of matched alleles in the local parasite population; in this trial, less than 10% of parasites had matched alleles. (Funded by the National Institutes of Health and others.).

Interest in multipurpose prevention of HIV and pregnancy: perspectives of women, men, health professionals and community stakeholders in two vaginal gel studies in southern Africa

OBJECTIVE

The pipeline of vaginal microbicides for HIV prevention has expanded to include products for multipurpose prevention, but the interests of potential users and those advising on use have not been sufficiently investigated. Rather, assumptions about interest in multipurpose prevention technologies (MPTs) are inferred from what is known about acceptability and use of microbicides or contraceptives.

DESIGN AND SETTING

This paper presents data on concerns and preferences for multipurpose prevention of HIV and pregnancy. Data were collected in two microbicide gel studies in Malawi and Zimbabwe. Participants were women using candidate vaginal products, their male partners, health professionals and community stakeholders.

METHODS

An individual interview was conducted with participants. Interviews were audio-recorded, transcribed, coded for content and analysed for key themes.

RESULTS

Participants indicated strong interest in a vaginal HIV prevention product that could also prevent pregnancy. Reasons for this interest were convenience, problems with adverse effects with current contraceptive methods, concerns about long-term effects of contraceptives, and concerns about the health burdens of HIV infection during pregnancy. The main disadvantage of an MPT was recognition that while interest in preventing HIV is constant, contraceptive needs change over time.

CONCLUSION

The study population indicated support for an MPT to prevent HIV and pregnancy. This support may be further strengthened if the product is also available for prevention of only HIV. Women and men will be more willing to use an MPT if they can be reassured that its use will have no long-term effect on fertility.

Utilization of family members to provide hospital care in Malawi: the role of Hospital Guardians

AIM

Like most of sub-Saharan Africa, Malawi suffers from a paucity of human resources in the health sector. With an average of one physician for every 50,000 persons, and a health care professional to in-patient population ratio of 1:277, patient care suffers. At Kamuzu Central Hospital (KCH) of Lilongwe, Malawi, family members, termed Hospital Guardians, are utilized to provide basic care for patients. The aim of our study is to characterize this population and explore their role in the health care system of KCH.

METHODS

Seventy three semi-qualitative surveys and nineteen in-depth interviews were conducted with hospital administrators, Guardians, nurses, and physicians from these wards. The results were analyzed using descriptive analysis and emergent coding.

RESULTS

It was found that Hospital Guardians were primarily female family members of patients and have a low literacy rate. They performed a wide range of daily tasks in patient care from wound care to advocacy. Despite their essential role in the health care system, the Guardians were provided with little support from the hospital. There was often conflict between the Guardians and hospital personnel due to overcrowding with more than one Guardian per patient; a lack of understanding of hospital rules and regulations; and a lack of respect for the Guardian role by hospital staff.

CONCLUSIONS

Until their role can be reduced by additional trained health care professionals, patient care could be improved by institutional support including a clarification of the role of the Hospital Guardians. Recommendations include a one-patient one-guardian policy; Guardian education; and enhancing Guardian resources.

Acceptance of repeat population-based voluntary counselling and testing for HIV in rural Malawi

OBJECTIVE

To examine the acceptance of repeat population-based voluntary counselling and testing (VCT) for HIV in rural Malawi.

METHODS

Behavioural and biomarker data were collected in 2004 and 2006 from approximately 3000 adult respondents. In 2004, oral swab specimens were collected and analysed using ELISA and confirmatory Western blot tests, while finger-prick rapid testing was done in 2006. We used cross-tabulations with chi(2) tests and significance tests of proportions to determine the statistical significance of differences in acceptance of VCT by year, individual characteristics and HIV risk.

RESULTS

First, over 90% of respondents in each round accepted the HIV test, despite variations in testing protocols. Second, the percentage of individuals who obtained their test results significantly increased from 67% in 2004, when the results were provided in randomly selected locations several weeks after the specimens were collected, to 98% in 2006 when they were made available immediately within the home. Third, whereas there were significant variations in the sociodemographic and behavioural profiles of those who were successfully contacted for a second HIV test, this was not the case for those who accepted repeat VCT. This suggests that variations in the success of repeat testing might come from contacting the individuals rather than from accepting the test or knowing the results.

CONCLUSIONS

Repeat HIV testing at home by trained healthcare workers from outside the local area, and with either saliva or blood, is almost universally acceptable in rural Malawi and, thus, likely to be acceptable in similar contexts.

Sertoli cell differentiation is induced both cell-autonomously and through prostaglandin signaling during mammalian sex determination

We have raised an antibody specifically recognizing endogenous mouse SRY protein and used it to investigate the molecular and cellular mode of action of SRY in testis determination. We find that expression of SRY protein closely mirrors the expression of Sry mRNA in mouse genital ridges and is detectable for 6 to 8 h after the mRNA ceases to be detectable. The subset of somatic cells that expresses SRY begins to express SOX9 almost immediately. Since these SOX9-positive cells go on to develop as Sertoli cells, it appears that SRY expression marks the pre-Sertoli cell lineage and leads to up-regulation of Sox9 expression cell-autonomously. However, a small proportion of SOX9-positive cells did not appear to express SRY, possibly reflecting the additional involvement of paracrine signaling in activating Sox9 transcription in these cells. We confirmed by ex vivo cell mixing experiments that SRY is able to engage receptor-mediated signaling to up-regulate Sox9 expression. Finally, we showed by employing specific inhibitors that the causative signaling molecule is prostaglandin D2 (PGD2) and that PGD2 can induce Sox9 transcription in cultured XX gonads. Our data indicate a mechanism whereby Sry uses both a cell-autonomous mechanism and a PGD2-mediated signaling mechanism to stimulate expression of Sox9 and induce the differentiation of Sertoli cells in vivo.

An estrogen receptor (ER)alpha deoxyribonucleic acid-binding domain knock-in mutation provides evidence for nonclassical ER pathway signaling in vivo

We created a nonclassical estrogen receptor (ER) knock-in mouse model by introducing a mutation that selectively eliminates classical ER signaling through estrogen response elements, while preserving the nonclassical ER pathway. Heterozygous nonclassical ER knock-in (NERKI) females are infertile. Their ovaries contain no corpora lutea, reflecting a defect in ovulation, and the stromal cells contain lipid droplets, suggesting altered steroidogenesis. The uteri are enlarged with evidence of cystic endometrial hyperplasia, and the mammary glands are hypoplastic. These phenotypic features indicate differential ER effects on growth and development in various estrogen-responsive tissues. These findings suggest that nonclassical ER signaling pathways play an important physiological role in the development and function of the reproductive system.

Adenovirus-directed expression of dominant negative estrogen receptor induces apoptosis in breast cancer cells and regression of tumors in nude mice

BACKGROUND

Estrogen receptors (ER) are expressed in about two thirds of human breast cancer, and are an important pharmacological target for treatment of these tumors. Dominant negative forms of the ER have been suggested as an alternative method to disrupt ER function. In this study, we examined the effect of dominant negative ER mutants (ER1-536 and L540Q) on ER-positive breast cancer cells in vitro and in vivo.

MATERIALS AND METHODS

ER-positive T47D breast cancer cells were infected with adenoviral vectors expressing ER1-536 and L540Q to examine the effects of the mutants on gene expression and cell growth. Adenoviral vectors containing the wild type ER (AdwtER) and beta-galactosidase gene (AdGal) were used as controls.

RESULTS

Ad1-536 or AdL540Q infection inhibited T47D cell growth and induced apoptosis, increasing Bax protein and phosphorylation of p38 mitogen-activated-protein kinase (MAPK). Consistent with the apoptotic effects in vitro, pre-infection of T47D cells with Ad1-536 or AdL540Q inhibited tumor formation when these cells were introduced into nude mice. In addition, injection of Ad1-536 and AdL540Q into pre-established T47D tumors induced tumor regression. Apoptosis, in conjunction with the activation of caspase-3 and phosphorylation of p38 MAPK, was detected in the shrinking tumors. Overexpression of wild-type ER by AdwtER infection also produced antiproliferative and apoptotic effects, but to a lesser extent than the ER1-536 and L540Q mutants.

CONCLUSIONS

These results indicate that dominant negative ER mutants have the potential to induce apoptosis of T47D cells and regression of tumors. The delivery of dominant negative ERs by adenoviral vectors may provide a useful tool for targeted therapy of ER-positive breast cancer.

Adenovirus-mediated targeted expression of toxic genes to adrenocorticotropin-producing pituitary tumors using the proopiomelanocortin promoter

Management of Cushing's disease remains challenging, despite advances in its diagnosis and treatment. Here, we describe a strategy for targeting the expression of toxic genes to ACTH-producing tumor cells using adenoviral vectors. The POMC promoter was used to express either a marker gene (beta-galactosidase) or a toxic gene [herpes simplex virus thymidine kinase (TK)]. In ACTH-producing AtT20 cells, infection with recombinant adenoviruses containing the POMC promoter (AdPOMCGal; AdPOMCTK) led to high-level gene expression. Stereotactic injection of AdPOMCGal into the rat pituitary resulted in localized expression of the beta-galactosidase transgene in corticotrope cells. Cytotoxicity studies were performed using the TK-containing vectors and treatment with ganciclovir. AdPOMCTK caused greater than 95% cytotoxicity of AtT20 cells at a viral dose (multiplicity of infection, 5 plaque-forming units/cell) that induced minimal toxicity using control viruses. No cellular toxicity was seen using a nonpituitary cell line (T47D breast tumor cells). AtT20 cells transplanted into nude mice induced features of Cushing's syndrome and were used as an in vivo model of ACTH-producing tumors. Injection of the AdPOMCTK virus caused significant regression of the transplanted AtT20 tumors. These studies suggest that the POMC promoter may provide a useful gene therapy strategy for the adjunctive treatment of pituitary tumors causing ACTH-dependent Cushing's syndrome.

A dominant negative CREB (cAMP response element-binding protein) isoform inhibits thyrocyte growth, thyroid-specific gene expression, differentiation, and function

cAMP mediates the effects of TSH by regulating thyroid follicular cell proliferation, differentiation, and function. To assess the functional importance of the cAMP response element binding protein (CREB) in thyroid follicular cell regulation in vivo, we targeted the expression of a dominant negative (DN) CREB isoform to the thyroid glands of transgenic mice using a tissue-specific promoter. Transgenic mice exhibited severe growth retardation and primary hypothyroidism. Serum levels of TSH were elevated 8-fold above normal levels, and T4 and T3 levels were low. Histologically, the mutant thyroid glands were characterized by poorly developed follicles that were heterogeneous in size with diminished colloid. Ciliated thyroid epithelial cells were observed in the transgenic thyroid glands, suggesting a failure of follicular cell differentiation. Consistent with this hypothesis, the DN CREB transgene inhibited the expression of an array of genes including thyroglobulin, thyroperoxidase, and the TSH receptor in semiquantitative RT-PCR experiments. Altered expression of the thyroid transcription factors Pax-8, TTF-1, and TTF-2 was also observed. These results demonstrate a critical role for CREB in thyroid growth, differentiation, and function in vivo.

A study of deafness in West Africa

Some 800 profoundly deaf children from 4 Yoruba states in Nigeria were assessed and examined in an attempt to identify the causes of deafness in this part of West Africa. It was found that measles, meningitis and rubella were the three major preventible diseases causing deafness. Genetic abnormalities, in contradistinction to other tropical countries, do not seem to be very important and chronic ear infections show different manifestations in this area to the situation reported in East Africa. The overwhelming problems that face the deaf and any possible extension of services for the deaf are detailed. In view of these it seems that the most cost-effective way of helping the deaf in Nigeria is by immunizing the population against those infectious diseases that cause the disability. This policy would accord with the recent initiatives by the United Nations: the International Year of the Child (I.Y.C.) and the International Year of the Disabled Person (I.Y.D.P.) as well as The Expanded Programme of Immunization (E.P.I.) of the World Health Organization.