Impact of human immunodeficiency virus infection in pregnant women on variant-specific immunity to malaria

Malaria and HIV coinfection in sub-Saharan Africa: prevalence, impact, and treatment strategies

Malaria and HIV, two of the world's most deadly diseases, are widespread, but their distribution overlaps greatly in sub-Saharan Africa. Consequently, malaria and HIV coinfection (MHC) is common in the region. In this paper, pertinent publications on the prevalence, impact, and treatment strategies of MHC obtained by searching major electronic databases (PubMed, PubMed Central, Google Scholar, ScienceDirect, and Scopus) were reviewed, and it was found that the prevalence of MHC in SSA was 0.7%-47.5% overall. Prevalence was 0.7%-47.5% in nonpregnant adults, 1.2%-27.8% in children, and 0.94%-37% in pregnant women. MHC was associated with an increased frequency of clinical parasitemia and severe malaria, increased parasite and viral load, and impaired immunity to malaria in nonpregnant adults, children, and pregnant women, increased in placental malaria and related outcomes in pregnant women, and impaired antimalarial drug efficacy in nonpregnant adults and pregnant women. Although a few cases of adverse events have been reported in coinfected patients receiving antimalarial and antiretroviral drugs concurrently, available data are very limited and have not prompted major revision in treatment guidelines for both diseases. Artemisinin-based combination therapy and cotrimoxazole are currently the recommended drugs for treatment and prevention of malaria in HIV-infected children and adults. However, concurrent administration of cotrimoxazole and sulfadoxine-pyrimethamine in HIV-infected pregnant women is not recommended, because of high risk of sulfonamide toxicity. Further research is needed to enhance our understanding of the impact of malaria on HIV, drug-drug interactions in patients receiving antimalarials and antiretroviral drugs concomitantly, and the development of newer, safer, and more cost-effective drugs and vaccines to prevent malaria in HIV-infected pregnant women.

Decrease in Numbers of Naive and Resting B Cells in HIV-Infected Kenyan Adults Leads to a Proportional Increase in Total and Plasmodium falciparum-Specific Atypical Memory B Cells

Human immunodeficiency virus type 1 (HIV-1) infection is associated with B cell activation and exhaustion, and hypergammaglobulinemia. How these changes influence B cell responses to coinfections such as malaria is poorly understood. To address this, we compared B cell phenotypes and Abs specific for the Plasmodium falciparum vaccine candidate apical membrane Ag-1 (AMA1) in HIV-infected and uninfected adults living in Kenya. Surprisingly, HIV-1 infection was not associated with a difference in serum AMA1-specific Ab levels. HIV-infected individuals had a higher proportion of total atypical and total activated memory B cells (MBCs). Using an AMA1 tetramer to detect AMA1-specific B cells, HIV-infected individuals were also shown to have a higher proportion of AMA1-specific atypical MBCs. However, this proportional increase resulted in large part from a loss in the number of naive and resting MBCs rather than an increase in the number of atypical and activated cells. The loss of resting MBCs and naive B cells was mirrored in a population of cells specific for an Ag to which these individuals were unlikely to have been chronically exposed. Together, the data show that changes in P. falciparum Ag-specific B cell subsets in HIV-infected individuals mirror those in the overall B cell population, and suggest that the increased proportion of atypical MBC phenotypes found in HIV-1-infected individuals results from the loss of naive and resting MBCs.

Risk factors for preterm birth among HIV-infected pregnant Ugandan women randomized to lopinavir/ritonavir- or efavirenz-based antiretroviral therapy

BACKGROUND

Protease inhibitor-based antiretroviral therapy (ART) has been associated with preterm birth in some studies. We examined risk factors for preterm birth among women randomized to lopinavir/ritonavir (LPV/r)- or efavirenz (EFV)-based ART.

METHODS

This was a planned secondary analysis of the PROMOTE-Pregnant Women and Infants Study, an open-label, randomized controlled trial comparing the risk of placental malaria among HIV-infected, ART-naive pregnant Ugandan women assigned to initiate LPV/r- or EFV-based ART at 12-28 weeks gestation. Gestational age was determined based on last menstrual period and ultrasound biometry. All women received bednets and trimethoprim-sulfamethoxazole. Stillbirths, spontaneous abortions, and multiple gestations were excluded from the primary analysis. Potential risk factors for preterm birth (<37 weeks gestation) were evaluated by univariate and multivariate logistic regression.

RESULTS

Three hundred fifty-six women were included in this analysis. At enrollment, median gestational age was 21 weeks and median CD4 cell count was 368 cells per cubic millimeter. 14.7% of deliveries in the EFV arm and 16.2% in the LPV/r arm were preterm. Preterm birth was associated with gestational weight gain below 0.1 kg/week versus 0.1 kg/week or more [odds ratio (OR) = 2.49; 95% confidence interval (CI): 1.38 to 4.47; P = 0.003]. Neither ART regimen of LPV/r versus EFV (OR = 1.12; 95% CI: 0.63 to 2.00; P = 0.69) nor placental malaria (OR = 0.74; 95% CI: 0.38 to 1.44; P = 0.37) was associated with preterm birth.

CONCLUSIONS

LPV/r was not associated with an increased risk of preterm birth compared with EFV. However, interventions are needed to address modifiable risk factors for preterm birth, such as nutritional status (ClinicalTrials.gov, NCT00993031).

Intermittent preventive treatment of malaria in pregnant women and infants: making best use of the available evidence

INTRODUCTION

Malaria continues to represent a huge global health burden on the most vulnerable populations. The Intermittent Preventive Treatment (IPT) strategy has been shown to be an efficacious intervention in preventing most of the deleterious effects of malaria in pregnant women and infants. Yet, the effectiveness of the IPT strategy may be impaired by the increasing resistance to sulfadoxine-pyrimethamine (SP), and the scarcity of alternative antimalarial drugs.

AREAS COVERED

This review examines all the available information on IPT, in an aim to provide the scientific community with a framework to understand the benefits and limitations of this malaria control strategy. It includes the understanding of the historical background of the IPT strategy, the drug's mechanisms of actions, updated information on current available evidence, the implications of drug resistance and choice of alternative drugs, and a comprehensive discussion on the perspectives of IPT for malaria control in pregnant women and infants.

EXPERT OPINION

IPT in pregnancy and infants is a cost-effective strategy that can contribute significantly to the control of malaria in endemic areas. Monitoring its effectiveness will allow tracking of progress, evaluation of the adequacy of currently used drugs and will highlight the eventual need for new therapies or alternative interventions.

HIV and malaria interactions: where do we stand?

Reversing the spread of HIV infection and the incidence of malaria constitute two of the Millenium Development Goals. However, despite recent achievements, both diseases still entail global heath problems. Furthermore, their overlapping geographical distribution raises concerns and challenges for potential immunological, clinical and therapeutic interactions. It has been reported that HIV infection increases malaria susceptibility and reduces the efficacy of antimalarial drugs. On the other hand, the effect of malaria on HIV-infected individuals has also been explored, with the parasitic infection increasing the risk of HIV disease progression and mother-to-child transmission of HIV. The spread of malaria and parasite resistance to antimalarials could also be accelerated by HIV-associated immunosuppresion. Current knowledge of the epidemiological, clinical, immunological and therapeutic interactions of the two diseases is reviewed in this article. We focus on the latest available data, pointing out key future research areas and challenges of the field.

Prevalence and correlates of insecticide-treated bednet use among HIV-1-infected adults in Kenya

HIV-1-infected adults are at increased risk for malaria. Insecticide-treated bednets protect individuals from malaria. Little is known about correlates of ownership and use of bednets among HIV-1-infected individuals. We conducted a cross-sectional survey of 388 HIV-1-infected adults recruited from three sites in Kenya (Kilifi, Kisii, and Kisumu) to determine factors associated with ownership and use of optimal bednets. We defined an optimal bednet as an untorn, insecticide-treated bednet. Of 388 participants, 134(34.5%) reported owning an optimal bednet. Of those that owned optimal bednets, most (76.9%) reported using it daily. In a multivariate model, higher socioeconomic status as defined as postsecondary education [OR = 2.8 (95% CI: 1.3-6.4), p = 0.01] and living in a permanent home [OR = 1.7(1.03-2.9), p = 0.04] were significantly associated with optimal bednet ownership. Among individuals who owned bednets, employed individuals were less likely [OR = 0.2(0.04-0.8), p = 0.01] and participants from Kilifi were more likely to use bednets [OR = 2.9 (95% CI 1.04-8.1), p = 0.04] in univariate analysis. Participants from Kilifi had the least education, lowest income, and lowest rate of employment. Our findings suggest that lower socioeconomic status is a barrier to ownership of an optimal bednet. However, consistent use is high once individuals are in possession of an optimal bednet. Increasing access to optimal bednets will lead to high uptake and use.

Reduction of antimalarial antibodies by HIV infection is associated with increased risk of Plasmodium falciparum cord blood infection

BACKGROUND

Plasmodium falciparum infection in pregnancy can lead to congenital malaria, which has detrimental health consequences for infants. Human immunodeficiency virus (HIV) might increase cord blood P. falciparum infection by decreasing maternal antimalarial-specific antibodies.

METHODS

HIV-negative (n=133) and HIV-positive (n=55) Mozambican pregnant women were assessed at delivery for maternal and cord P. falciparum infection by quantitative polymerase chain reaction (qPCR) and P. falciparum-specific antibodies by enzyme-linked immunosorbent assay and flow cytometry.

RESULTS

Prevalence of qPCR-detected cord blood infection was 8.0%. Risk of cord infection was increased in presence of HIV (adjusted odds ratio [AOR], 3.80; P=.04) and placental malaria (AOR, 22.08; P=.002) after adjusting for clinical variables. The odds of having a high immunoglobulin G response to chondrotin sulphate A-binding infected erythrocytes, parasite lysate, and erythrocyte-binding antigen-175 were reduced among HIV-positive women (P < .001, .048, and .056, respectively) and among women with cord P. falciparum infection (P = .009, .04, and .046, respectively). In multivariate analysis including maternal HIV status, placental malaria, and antibody responses, HIV was no longer associated with cord blood infection (P = .11).

CONCLUSIONS

HIV-associated impairment of antibody responses in pregnant women may contribute to a higher transmission of P. falciparum to their infants.

Parity and placental infection affect antibody responses against Plasmodium falciparum during pregnancy

Women are at higher risk of Plasmodium falciparum infection when pregnant. The decreasing risk of malaria with subsequent pregnancies is attributed to parity-dependent acquisition of antibodies against placental parasites expressing variant surface antigens, VAR2CSA, that mediate placental sequestration through adhesion to chondroitin sulfate A (CSA). However, modulation of immunity during pregnancy may also contribute to increase the risk of malaria. We compared antibody responses among 30 Mozambican primigravidae and 60 multigravidae at delivery, 40 men, and 40 children. IgG levels were measured against the surface antigens of erythrocytes infected with P. falciparum isolated from 12 pregnant women (4 placental and 8 peripheral blood isolates) and 26 nonpregnant hosts. We also measured IgG levels against merozoite recombinant antigens and total IgG. Placental P. falciparum infection was associated with increased levels of total IgG as well as IgG levels against merozoite antigens and parasite isolates from pregnant and nonpregnant hosts. We therefore stratified comparisons of antibody levels by placental infection. Compared to multigravidae, uninfected primigravidae had lower total IgG as well as lower levels of IgGs against peripheral blood isolates from both pregnant and nonpregnant hosts. These differences were not explained by use of bed nets, season at delivery, neighborhood of residence, or age. Compared to men, infected primigravidae had higher levels of IgGs against isolates from pregnant women and CSA-binding lines but not against other isolates, supporting the concept of a pregnancy-specific development of immunity to these parasite variants. Results of this study show that parity and placental infection can modulate immune responses during pregnancy against malaria parasites.

The relationship of Plasmodium falciparum humeral immunity with HIV-1 immunosuppression and treatment efficacy in Zambia

Background

HIV-1 infection affects malaria humeral immunity during pregnancy, but data for non-pregnant adults are lacking. This study reports the impact of HIV-1 infection and other variables on the level of malaria humeral immunity in adults with clinical malaria and whether humeral immune suppression was a risk factor for treatment failure.

Methods

Sera of 224 HIV-1 infected and 115 uninfected adults were compared for IgG to merozoite antigens AMA-1 and MSP2 (3D7 and FC27 types) determined by ELISA, and for IgG to the Variant Surface Antigens (VSA) of three different parasite line E8B, A4 and HCD6 determined by flow cytometry.

Results

Compared to HIV-1 uninfected adults, AMA-1 IgG was lower in HIV-1 infected (P = 0.02) and associated with low CD4 count AMA-1 IgG (P = 0.003). Low IgG to all three merozoite antigens was associated with less anemia (P = 0.03). High parasite load was associated with low MSP2 IgG 3D7 and FC27 types (P = 0.02 and P = 0.08). Antibody levels to VSA did not differ between HIV-1 infected and uninfected adults. However, low VSA IgGs were associated with high parasite load (P ≤ 0.002 for each parasite line) and with treatment failure (P ≤ 0.04 for each parasite line).

Conclusion

HIV-1 affects humeral responses to AMA-1, but seems to marginally or not affect humeral responses to other merozoite antigens and VSAs. The latter were important for controlling parasite density and predict treatment outcome.

The Impact of HIV and Malaria Coinfection: What Is Known and Suggested Venues for Further Study

HIV and malaria have similar global distributions. Annually, 500 million are infected and 1 million die because of malaria. 33 million have HIV and 2 million die from it each year. Minor effects of one infection on the disease course or outcome for the other would significantly impact public health because of the sheer number of people at risk for coinfection. While early population-based studies showed no difference in outcomes between HIV-positive and HIV-negative individuals with malaria, more recent work suggests that those with HIV have more frequent episodes of symptomatic malaria and that malaria increases HIV plasma viral load and decreases CD4+ T cells. HIV and malaria each interact with the host's immune system, resulting in a complex activation of immune cells, and subsequent dysregulated production of cytokines and antibodies. Further investigation of these interactions is needed to better define effects of coinfection.