[Show abstract][Hide abstract] ABSTRACT: Asymptomatic and symptomatic malaria during pregnancy has consequences for both mother and her offspring. Unfortunately, there is insufficient information on the safety and efficacy of most antimalarials in pregnancy. Indeed, clinical trials assessing antimalarial treatments systematically exclude pregnancy for fear of teratogenicity and embryotoxicity. The little available information originates from South East Asia while in sub-Saharan Africa such information is still limited and needs to be provided.
A Phase 3, non-inferiority, multicentre, randomized, open-label clinical trial on safety and efficacy of 4 ACT when administered during pregnancy was carried out in 4 African countries: Burkina Faso, Ghana, Malawi and Zambia. This is a four arm trial using a balanced incomplete block design. Pregnant women diagnosed with malaria are randomised to receive either amodiaquine-artesunate (AQ-AS), dihydroartemisinin-piperaquine (DHA-PQ), artemether-lumefantrine (AL), or mefloquine-artesunate (MQAS). They are actively followed up until day 63 post-treatment and then monthly until 4-6 weeks post-delivery. The offspring is visited at the time of the first birthday. The primary endpoint is treatment failure (PCR adjusted) at day 63 and safety profiles. Secondary endpoints included PCR unadjusted treatment failure up to day 63, gametocyte carriage, Hb changes, placenta malaria, mean birth weight and low birth weight. The primary statistical analysis will use the combined data from all 4 centres, with adjustment for any centre effects, using an additive model for the response rates. This will allow the assessment of all 6 possible pair-wise treatment comparisons using all available data.
The strength of this trial is the involvement of several African countries, increasing the generalisability of the results. In addition, it assesses most ACTs currently available, determining their relative '-value-' compared to others. The balanced incomplete block design was chosen because using all 4-arms in each site would have increased complexity in terms of implementation. Excluding HIV-positive pregnant women on antiretroviral drugs may be seen as a limitation because of the possible interactions between antiretroviral and antimalarial treatments. Nevertheless, the results of this trial will provide the evidence base for the formulation of malaria treatment policy for pregnant women in sub-Saharan Africa.Trial registration: NCT00852423.
Reproductive Health 01/2015; 12(5). DOI:10.1186/1742-4755-12-5 · 1.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: : UNAIDS has set a goal of achieving the elimination of mother-to-child transmission (eMTCT) of HIV by 2015 and keeping HIV-positive (HIV+) mothers alive. In pursuit of this goal, in 2011, the Malawi Ministry of Health (MoH) adopted the Option B+ strategy, which entails lifelong antiretroviral treatment for all HIV+ mothers, irrespective of severity of HIV infection. Poor mother-child pair retention is one of the major challenges against achieving this goal. To improve retention of mother-infant pairs in the eMTCT continuum of care, the Promoting Retention among Infants and Mothers Effectively (PRIME) study is evaluating the effectiveness of 3 models of health care delivery namely, mother-infant pair clinics, which deliver integrated HIV and non-HIV services, mother-infant pair clinics plus electronic text message (SMS) reminders for mother-infant pairs who miss scheduled eMTCT follow-up clinics, and current standard of care. The primary outcome is "the proportion of HIV+ mothers and/or HIV-exposed infants (HEI) retained in eMTCT care at 12 months postpartum and received recommended HIV and non-HIV services during preceding scheduled visits." This 3-arm cluster randomized intervention study is being implemented in 30 primary health facilities (10 facilities per arm) in Mangochi and Salima districts, Malawi. At each clinic, a total of 41 HIV+ mothers attending maternal and child health services are being recruited and followed up for 18 months postpartum. This article describes the study methodology and interventions, successes and challenges experienced during the first 12 months of study implementation and relevance of study results to Malawi and other countries adopting the Option B+ strategy.
[Show abstract][Hide abstract] ABSTRACT: Sulfadoxine-resistant Plasmodium falciparum undermines malaria prevention with sulfadoxine/pyrimethamine. Parasites with a highly resistant mutant dihydropteroate synthase (dhps) haplotype have recently emerged in eastern Africa; they negated preventive benefits of sulfadoxine/pyrimethamine, and might exacerbate placental malaria. We explored emerging lineages of dhps mutant haplotypes in Malawi, the Democratic Republic of the Congo, and Tanzania by using analyses of genetic microsatellites flanking the dhps locus. In Malawi, a triple-mutant dhps SGEG (mutant amino acids are underlined) haplotype emerged in 2010 that was closely related to pre-existing double-mutant SGEA haplotypes, suggesting local origination in Malawi. When we compared mutant strains with parasites from the Democratic Republic of the Congo and Tanzania by multiple independent analyses, we found that SGEG parasites were partitioned into separate lineages by country. These findings support a model of local origination of SGEG
dhps haplotypes, rather than geographic diffusion, and have implications for investigations of emergence and effects of parasite drug resistance.
[Show abstract][Hide abstract] ABSTRACT: The Malawi Longitudinal Study of Families and Health (MLSFH) is one of very few long-standing, publicly available longitudinal cohort studies in a sub-Saharan African (SSA) context. It provides a rare record of more than a decade of demographic, socioeconomic and health conditions in one of the world's poorest countries. The MLSFH was initially established in 1998 to study social network influences on fertility behaviours and HIV risk perceptions, and over time the focus of the study expanded to include health, sexual behaviours, intergenerational relations and family/household dynamics. The currently available data include MLSFH rounds collected in 1998, 2001, 2004, 2006, 2008, 2010 and 2012 for up to 4 000 individuals, providing information about socioeconomic and demographic characteristics, sexual behaviours, marriage, household/family structure, risk perceptions, social networks and social capital, intergenerational relations, HIV/AIDS and other dimensions of health. The MLSFH public use data can be requested on the project website: http://www.malawi.pop.upenn.edu/.
International Journal of Epidemiology 03/2014; 44(2). DOI:10.1093/ije/dyu049 · 9.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Compared to HIV-negative women, HIV-infected women have increased risk of low birth weight (LBW) and preterm delivery (PTD). We assessed whether severity of maternal HIV-1 disease was associated with LBW or PTD.
Secondary analysis of The Malaria and HIV in Pregnancy prospective cohort, which enrolled HIV-positive, pregnant Malawian women from 2000-2004. Included participants (n=809) were normotensive, antiretroviral treatment naïve women who delivered a live, singleton infant. Binomial regression models were used to assess the unadjusted and adjusted prevalence ratios (PRs) and 95% confidence intervals (CI) of the effect of severity of HIV-1 disease, defined by viral load and CD4-positive T-cell counts, on prevalence of LBW and PTD.
In unadjusted analyses, among those with malaria (n=198), there was no association between severity of HIV-1 infection and LBW, while among women without malaria (n=611), we observed a harmful association between both increasing peripheral viral load and LBW (PR: 1.44 per one-log10 increase, 95% CI: 1.12, 1.86) and placental viral load and LBW (PR: 1.24 per one-log10 increase, 95% CI: 1.00, 1.53). We observed a similar association between increasing placental viral load and PTD (PR: 1.33 per one-log10 increase, 95% CI: 1.04, 1.69). These associations persisted in multivariate models adjusted for residence, maternal education, primigravid status, and maternal anemia.
In malaria-negative women, maternal HIV-1 disease severity was significantly associated with increased prevalence of LBW and PTD. Such an association was not found in the malaria-infected women.
[Show abstract][Hide abstract] ABSTRACT: Approximately 20% of all HIV-1 mother-to-child transmission (MTCT) occurs in utero (IU). In a chronic HIV-infection, HIV-1 exists as a complex swarm of genetic variants, and following IU MTCT, viral genomic diversity is restricted through a mechanism that remains to be described. The 5' U3R region of the HIV-1 long terminal repeat (LTR) contains multiple transcription factor (TF) binding sites and regulates viral transcription. In this study, we tested the hypothesis that sequence polymorphisms in the U3R region of LTR are associated with IU MTCT. To this end, we used single template amplification to isolate 517 U3R sequences from maternal, placental, and infant plasma derived from seventeen HIV-infected Malawian women; eight whose infants remained HIV-uninfected (NT) and nine whose infants became HIV-infected IU. U3R sequences show pairwise diversities ranging from 0.6 - 2.3%; U3R sequences from one participant contained two, three, or four putative NF-κB binding sites. Phylogenetic reconstructions indicated that U3R sequences from eight of nine IU participants were consistent with placental compartmentalization of HIV-1 while only one of eight NT cases was consistent with such compartmentalization. Specific TF sequence polymorphisms were not significantly associated with IU MTCT. To determine if replication efficiency of the U3R sequences was associated with IU MTCT, we cloned 90 U3R sequences and assayed promoter activity in multiple cell lines. Although we observed significant, yet highly variable promoter activity and TAT-induction of promoter activity, in the cell lines tested, there was no association between measured promoter activity and MTCT status. Thus, we were unable to detect a promoter genotype or phenotype associated with IU MTCT.
AIDS research and human retroviruses 07/2013; 30(1). DOI:10.1089/AID.2013.0026 · 2.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Breastfeeding is a leading cause of infant HIV-1 infection in the developing world, yet only a minority of infants exposed to HIV-1 via breastfeeding become infected. As a genetic bottleneck severely restricts the number of postnatally-transmitted variants, genetic or phenotypic properties of the virus Envelope (Env) could be important for the establishment of infant infection. We examined the efficiency of virologic functions required for initiation of infection in the gastrointestinal tract and the neutralization sensitivity of HIV-1 Env variants isolated from milk of three postnatally-transmitting mothers (n=13 viruses), five clinically-matched nontransmitting mothers (n=16 viruses), and seven postnatally-infected infants (n = 7 postnatally-transmitted/founder (T/F) viruses).
There was no difference in the efficiency of epithelial cell interactions between Env virus variants from the breast milk of transmitting and nontransmitting mothers. Moreover, there was similar efficiency of DC-mediated trans-infection, CCR5-usage, target cell fusion, and infectivity between HIV-1 Env-pseudoviruses from nontransmitting mothers and postnatal T/F viruses. Milk Env-pseudoviruses were generally sensitive to neutralization by autologous maternal plasma and resistant to breast milk neutralization. Infant T/F Env-pseudoviruses were equally sensitive to neutralization by broadly-neutralizing monoclonal and polyclonal antibodies as compared to nontransmitted breast milk Env variants.
Postnatally-T/F Env variants do not appear to possess a superior ability to interact with and cross a mucosal barrier or an exceptional resistance to neutralization that define their capability to initiate infection across the infant gastrointestinal tract in the setting of preexisting maternal antibodies.
[Show abstract][Hide abstract] ABSTRACT: Background:
Health systems have experienced unprecedented stress in recent years, and as yet no consensus has emerged as to how to deal with the multiple burden of disease in the context of HIV and AIDS and other competing health priorities. Priority setting is essential, yet this is a complex, multifaceted process. Drawing on a study conducted in five African countries, this paper explores different stakeholders' perceptions of health priorities, how priorities are defined in practice, the process of resource allocation for HIV and Health and how different stakeholders perceive this.
A sub-analysis was conducted of selected data from a wider qualitative study that explored the interactions between health systems and HIV and AIDS responses in five sub-Saharan countries (Burkina Faso, the Democratic Republic of Congo, Ghana, Madagascar and Malawi). Key background documents were analysed and semi-structured interviews (n = 258) and focus group discussions (n = 45) were held with representatives of communities, health personnel, decision makers, civil society representatives and development partners at both national and district level.
Health priorities were expressed either in terms of specific health problems and diseases or gaps in service delivery requiring a strengthening of the overall health system. In all five countries study respondents (with the exception of community members in Ghana) identified malaria and HIV as the two top health priorities. Community representatives were more likely to report concerns about accessibility of services and quality of care. National level respondents often referred to wider systemic challenges in relation to achieving the Millennium Development Goals (MDGs). Indeed, actual priority setting was heavily influenced by international agendas (e.g. MDGs) and by the ways in which development partners were supporting national strategic planning processes. At the same time, multi-stakeholder processes were increasingly used to identify priorities and inform sector-wide planning, whereby health service statistics were used to rank the burden of disease. However, many respondents remarked that health system challenges are not captured by such statistics.In all countries funding for health was reported to fall short of requirements and a need for further priority setting to match actual resource availability was identified. Pooled health sector funds have been established to some extent, but development partners' lack of flexibility in the allocation of funds according to country-generated priorities was identified as a major constraint.
Although we found consensus on health priorities across all levels in the study countries, current funding falls short of addressing these identified areas. The nature of external funding, as well as programme-specific investment, was found to distort priority setting. There are signs that existing interventions have had limited effects beyond meeting the needs of disease-specific programmes. A need for more comprehensive health system strengthening (HSS) was identified, which requires a strong vision as to what the term means, coupled with a clear strategy and commitment from national and international decision makers in order to achieve stated goals. Prospective studies and action research, accompanied by pilot programmes, are recommended as deliberate strategies for HSS.
BMC Public Health 12/2012; 12(1):1071. DOI:10.1186/1471-2458-12-1071 · 2.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Human immunodeficiency virus (HIV) is common in pregnant women in many malaria-endemic regions and may increase risk of placental parasitemia. Placental malaria is more common in primigravidae than multigravidae, but the relationship between HIV and malaria across gravidities is not well characterized. We recruited pregnant Malawian women during the second trimester and followed them until delivery. Parasitemia was assessed at enrollment, follow-up visits, and delivery, when placental blood was sampled. There was no difference in risk of parasitemia between HIV-positive and HIV-negative primigravidae. Among multigravidae, HIV-infected women had greater than twice the risk of parasitemia as HIV-uninfected women throughout follow-up. Human immunodeficiency virus was also associated with more frequent peripheral parasitemia in multigravidae but not primigravidae. Both HIV and primigravid status were independently associated with higher peripheral and placental parasite densities. Although risk of parasitemia is lower in multigravidae than primigravidae, the HIV effect on risk of malaria is more pronounced in multigravidae.
The American journal of tropical medicine and hygiene 10/2012; 87(6). DOI:10.4269/ajtmh.2012.12-0392 · 2.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Plasmodium falciparum and human immunodeficiency virus (HIV) are both risk factors for low birth weight (LBW) and maternal anemia, and they may interact to increase risk of adverse pregnancy outcomes. In 2005 and 2006, we followed 831 pregnant women attending antenatal care clinics in southern Malawi through delivery. HIV was associated with increased risk of LBW (adjusted prevalence ratio [PR(adj)] = 3.08, 95% confidence interval [CI] = 1.40, 6.79). Having greater than or equal to three episodes of peripheral parasitemia was also associated with increased risk of LBW (PR(adj) = 2.68, 95% CI = 1.06, 6.79). Among multigravidae, dual infection resulted in 9.59 (95% CI = 2.51, 36.6) times the risk of LBW compared with uninfected multigravidae. HIV infection and placental parasitemia were each associated with increased risk of anemia. Thus, HIV infection and parasitemia are important independent risk factors for adverse pregnancy outcomes. Among multigravidae, HIV infection and placental parasitemia may interact to produce an impact greater than the sum of their independent effects.
The American journal of tropical medicine and hygiene 07/2012; 87(1):29-34. DOI:10.4269/ajtmh.2012.11-0380 · 2.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In Southern Malawi, the fishing industry is highly gendered, with men carrying out the fishing and women processing, drying and selling the fish. Research has shown that individuals living in fishing communities in low-income countries are particularly vulnerable to HIV infection. One of the key drivers of HIV in fishing communities is transactional sex. In the fishing industry this takes the form of "fish-for-sex" networks where female fish traders exchange sex with fishermen for access to or more favourable prices of fish. By controlling the means of production, the power dynamics in these exchanges favour men and can make it more difficult for women to negotiate safe sex.
Qualitative methods were used to collect data on gendered drivers of transactional sex in the fishing community and how different groups perceive HIV risk in these transactions. Observation, focus group discussions and semi-structured interviews were undertaken with members of the fishing communities, including men and women directly and indirectly involved in fishing.
In fishing communities transactional sex was prevalent across a spectrum ranging from gift giving within relationships, to sex for fish exchanges, to sex worker encounters. Power differences between couples in transactional sexual encounters shape individual's abilities to negotiate condom use (with women being at a particularly disadvantaged negotiating position). The context and motivations for transactional sex varied and was mediated by economic need and social position both of men and women. Female fish traders new to the industry and boat crew members who travelled for work and experienced difficult living conditions often engaged in transactional sex.
Transactional sex is common in Malawian fishing communities, with women particularly vulnerable in negotiations because of existing gendered power structures. Although knowledge and understanding of the HIV risk associated with transactional sex was common, this did not appear to result in the adoption of risk reduction strategies. This suggests that specially targeted strategies to increase women's economic empowerment and tackle the structural drivers of women's HIV risk could be important in fishing communities.
Journal of the International AIDS Society 06/2012; 15 Suppl 1(Suppl 1):1-9. DOI:10.7448/IAS.15.3.17364 · 5.09 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Antenatal intermittent preventive therapy with 2 doses of sulfadoxine-pyrimethamine (IPTp-SP) is the mainstay of efforts in sub-Saharan Africa to prevent pregnancy-associated malaria (PAM). Recent studies report that drug resistance may cause IPTp-SP to exacerbate PAM morbidity, raising fears that current policies will cause harm as resistance spreads.
We conducted a serial, cross-sectional analysis of the relationships between IPTp-SP receipt, SP-resistant Plasmodium falciparum, and PAM morbidity in delivering women during a period of 9 years at a single site in Malawi. PAM morbidity was assessed by parasite densities, placental histology, and birth outcomes.
The prevalence of parasites with highly SP-resistant haplotypes increased from 17% to 100% (P < .001), and the proportion of women receiving full IPTp (≥2 doses) increased from 25% to 82% (P < .001). Women who received full IPTp with SP had lower peripheral (P = .018) and placental (P < .001) parasite densities than women who received suboptimal IPTp (<2 doses). This effect was not significantly modified by the presence of highly SP-resistant haplotypes. After adjustment for covariates, the receipt of SP in the presence of SP-resistant P. falciparum did not exacerbate any parasitologic, histologic, or clinical measures of PAM morbidity.
In this longitudinal study of malaria at delivery, the receipt of SP as IPTp did not potentiate PAM morbidity despite the increasing prevalence and fixation of SP-resistant P. falciparum haplotypes. Even when there is substantial resistance, SP may be used in modified IPTp regimens as a component of comprehensive antenatal care.
[Show abstract][Hide abstract] ABSTRACT: To determine whether there is an association between cytokine and chemokine levels in plasma isolated from the placenta and HIV-1 mother-to-child transmission (MTCT).
We designed a case-control study of HIV-infected, pregnant women enrolled in the Malaria and HIV in Pregnancy cohort. Participants were recruited in Blantyre, Malawi, from 2000 to 2004. Patients were women whose children were HIV-1 DNA-positive at birth (in-utero MTCT) or HIV-1 DNA-negative at birth and HIV-1 DNA-positive at 6 weeks postpartum (intrapartum MTCT); controls were women whose children were HIV-1 DNA-negative both at birth and 6 weeks postpartum.
After delivery, blood was isolated from an incision on the basal plate of the placenta. We used a Bio-Plex human cytokine assay (Bio-Rad, Hercules, California USA) to simultaneously quantify 27 cytokines, chemokines and growth factors in placental plasma. HIV-1 RNA copies were quantified with the Roche Amplicor kit.
Levels of interleukin (IL) 4, IL-5, IL-6, IL-7, IL-9, eotaxin, IL-1Ra and interferon gamma-induced protein 10 (IP-10) were significantly elevated in placental plasma isolated from cases of in-utero HIV-1 MTCT. In contrast, only granulocyte colony-stimulating factor was elevated in placental plasma isolated from cases of intrapartum MTCT. After adjusting for maternal age, gestational age and peripheral CD4(+) T-cell count, every log(10) increase in placental IP-10 was associated with a three-fold increase in the prevalence of in-utero HIV-1 MTCT.
Elevated cytokine and chemokine levels in placental plasma were associated with in-utero and not intrapartum MTCT. IP-10, which is both a T-cell chemokine and potentiator of HIV-replication, was robustly and independently associated with prevalent, in-utero MTCT.
AIDS (London, England) 02/2012; 26(6):685-94. DOI:10.1097/QAD.0b013e3283519b00 · 5.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sulfadoxine-pyrimethamine (SP) has been widely deployed in Africa for malaria control and molecular evidence of parasite drug-resistance is prevalent. However, the temporal effects on the selection of Plasmodium falciparum are not well understood. We conducted a retrospective serial cross-sectional study between 1997 and 2006 to investigate changes in drug-resistant malaria among pregnant women delivering at a single hospital in Blantyre, Malawi. P. falciparum parasites were genotyped for parasite clone multiplicity and drug-resistance mutations, and the strength of selection upon mutant genotypes was quantified. Five mutations in the dihydrofolate reductase and dihydropteroate synthase genes began at moderate frequencies and achieved fixation by 2005; the frequency of the highly-SP-resistant "quintuple mutant" haplotype increased from 19% to 100%. The selective advantage of alleles and haplotypes were quantified with selection coefficients: Selection was positive on all mutant alleles and haplotypes associated with SP resistance, and the relative fitness of the quintuple mutant haplotype was 0.139 (95% C.I. 0.067-0.211), indicating a substantial positive selective advantage. Mutations that confer higher levels of resistance to SP did not emerge. SP-resistant haplotypes were rapidly selected for and fixed in P. falciparum populations infecting pregnant women while SP was widely deployed in Malawi. These results underscore the pressing need for new preventive measures for pregnancy-associated malaria and provide a real-world model of the selection landscape malaria parasites.
Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 11/2011; 12(2):282-90. DOI:10.1016/j.meegid.2011.11.006 · 3.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although HIV testing and counseling (HTC) uptake has increased dramatically in Africa, facility-based services are unlikely to ever meet ongoing need to the full. A major constraint in scaling up community and home-based HTC services is the unacceptability of receiving HTC from a provider known personally to prospective clients. We investigated the potential of supervised oral HIV self-testing from this perspective.
Adult members of 60 households and 72 members of community peer groups in urban Blantyre, Malawi, were selected using population-weighted random cluster sampling. Participants were offered self-testing plus confirmatory HTC (parallel testing with two rapid finger-prick blood tests), standard HTC alone, or no testing. 283 (95.6%) of 298 selected adults participated, including 136 (48.0%) men. 175 (61.8%) had previously tested (19 known HIV positive), although only 64 (21.5%) within the last year. HIV prevalence was 18.5%. Among 260 (91.9%) who opted to self-test after brief demonstration and illustrated instructions, accuracy was 99.2% (two false negatives). Although 98.5% rated the test "not hard at all to do," 10.0% made minor procedural errors, and 10.0% required extra help. Most participants indicated willingness to accept self-test kits, but not HTC, from a neighbor (acceptability 94.5% versus 46.8%, p = 0.001).
Oral supervised self-testing was highly acceptable and accurate, although minor errors and need for supervisory support were common. This novel option has potential for high uptake at local community level if it can be supervised and safely linked to counseling and care.
PLoS Medicine 10/2011; 8(10):e1001102. DOI:10.1371/journal.pmed.1001102 · 14.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: HIV infection increases the burden of disease of malaria in pregnancy, in part by impairing the development of immunity. We measured total IgG and phagocytic antibodies against variant surface antigens of placental-type CS2 parasites in 187 secundigravidae (65% HIV infected). In women with placental malaria infection, phagocytic antibodies to CS2(VSA) were decreased in the presence of HIV (p = 0.011) and correlated positively with infant birth weight (coef = 3.57, p = 0.025), whereas total IgG to CS2(VSA) did not. Phagocytic antibodies to CS2(VSA) are valuable tools to study acquired immunity to malaria in the context of HIV co-infection. Secundigravidae may be an informative group for identification of correlates of immunity.
PLoS ONE 07/2011; 6(7):e22491. DOI:10.1371/journal.pone.0022491 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: HIV infections are initiated by a limited number of variants that diverge into a diverse quasispecies swarm. During in utero mother-to-child transmission (IU MTCT), transmitted viral variants must pass through multiple unique environments, and our
previously published data suggest a nonstochastic model of transmission. As an alternative to a stochastic model of viral
transmission, we hypothesize that viral selection in the placental environment influences the character of the viral quasispecies
when HIV-1 is transmitted in utero. To test this hypothesis, we used single-template amplification to isolate HIV-1 envelope gene (env) sequences from both peripheral plasma and the placentas of eight nontransmitting (NT) and nine IU-transmitting participants.
Statistically significant compartmentalization between peripheral and placental HIV-1 env was detected in one of the eight NT cases and six of the nine IU MTCT cases. In addition, viral sequences isolated from IU
MTCT placental tissue showed variation in env V1 loop lengths compared to matched maternal sequences, while NT placental env sequences did not. Finally, comparison of env sequences from NT and IU MTCT participants indicated statistically significant differences in Kyte-Doolittle hydropathy in
the signal peptide, C2, V3, and C3 regions. Our working hypothesis is that the hydropathy differences in Env associated with
IU MTCT alter viral cellular tropism or affinity, allowing HIV-1 to efficiently infect placentally localized cells.
Journal of Virology 07/2011; 85(14):7142-52. DOI:10.1128/JVI.01955-10 · 4.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Subtype C human immunodeficiency virus type 1 (HIV-1C) continues to cause the majority of new cases of mother-to-child transmission (MTCT), and yet there are limited data on HIV-1C transmission. We amplified env from plasma RNA for 19 HIV-1C MTCT pairs, 10 transmitting in utero (IU) and 9 transmitting intrapartum (IP). There was a strong genetic bottleneck between all mother-infant pairs, with a majority of transmission events involving the transmission of a single virus. env genes of viruses transmitted to infants IP, but not IU, encoded Env proteins that were shorter and had fewer putative N-linked glycosylation sites in the V1-V5 region than matched maternal sequences. Viruses pseudotyped with env clones representative of each maternal and infant population were tested for neutralization sensitivity. The 50% inhibitory concentration of autologous serum was similar against both transmitted (infant) and nontransmitted (maternal) viruses in a paired analysis. Mother and infant Env proteins were also similar in sensitivity to soluble CD4, to a panel of monoclonal antibodies, and to heterologous HIV-1C sera. In addition, there was no difference in the breadth or potency of neutralizing antibodies between sera from 50 nontransmitting and 23 IU and 23 IP transmitting HIV-1C-infected women against four Env proteins from heterologous viruses. Thus, while a strong genetic bottleneck was detected during MCTC, with viruses of shorter and fewer glycosylation sites in env present in IP transmission, our data do not support this bottleneck being driven by selective resistance to antibodies.
Journal of Virology 05/2011; 85(16):8253-62. DOI:10.1128/JVI.00197-11 · 4.44 Impact Factor