Breast-feeding and Transmission of HIV-1

Commensal bacteria inhibit viral infections via a tryptophan metabolite

There is growing appreciation that commensal bacteria impact the outcome of viral infections, though the specific bacteria and their underlying mechanisms remain poorly understood. Studying a simian-human immunodeficiency virus (SHIV)-challenged cohort of pediatric nonhuman primates, we bioinformatically associated Lactobacillus gasseri and the bacterial family Lachnospiraceae with enhanced resistance to infection. We experimentally validated these findings by demonstrating two different Lachnospiraceae isolates, Clostridium immunis and Ruminococcus gnavus, inhibited HIV replication in vitro and ex vivo. Given the link between tryptophan catabolism and HIV disease severity, we found that an isogenic mutant of C. immunis that lacks the aromatic amino acid aminotransferase (ArAT) gene, which is key to metabolizing tryptophan into 3-indolelactic acid (ILA), no longer inhibits HIV infection. Intriguingly, we confirmed that a second commensal bacterium also inhibited HIV in an ArAT-dependent manner, thus establishing the generalizability of this finding. In addition, we found that purified ILA inhibited HIV infection by agonizing the aryl hydrocarbon receptor (AhR). Given that the AhR has been implicated in the control of multiple viral infections, we demonstrated that C. immunis also inhibited human cytomegalovirus (HCMV) infection in an ArAT-dependent manner. Importantly, metagenomic analysis of individuals at-risk for HIV revealed that those who ultimately acquired HIV had a lower fecal abundance of the bacterial ArAT gene compared to individuals who did not, which indicates our findings translate to humans. Taken together, our results provide mechanistic insights into how commensal bacteria decrease susceptibility to viral infections. Moreover, we have defined a microbiota-driven antiviral pathway that offers the potential for novel therapeutic strategies targeting a broad spectrum of viral pathogens.

Immunization of laboratory animal workers: occupational health and safety aspects

Occupational immunization is an integral part of institutional occupational safety and health (OSH) programs. Laboratory animal workers (LAWs) are personnel working with various small and large vertebrate animals. LAWs are at the risk of contracting a myriad of zoonotic infections as they are occupationally exposed to animals and their biological products. Immunizing employees against such zoonotic pathogens is the best way to prevent disease transmission. This review provides information on various zoonotic diseases, vaccines available to protect against such infections, and vaccination schedules. Certain sections of institutional occupational immunization programs such as risk evaluation, immunizing special categories of personnel and exemption from immunization among others are also described. Additionally, the authors have discussed various probable modes of impact through which occupational immunization of laboratory animal workers fulfills different United Nations Sustainable Development Goals.

A Quality Improvement Initiative to Increase the Milk Donation to the Human Milk Bank Post-Coronavirus Disease-19 Pandemic

Background and Objective: Donor human milk (DHM) from the human milk bank (HMB) is the next best alterative in circumstances when mother's own milk is not available. There was a steep decline in the volume of DHM collected during the coronavirus disease-19 (COVID-19) pandemic due to various factors, while DHM demand increased. Hence, a quality improvement (QI) study was conducted to increase the volume of milk donation to HMB from postpandemic baseline of 300-400 to 1,000 mL/day over 8 weeks. Materials and Methods: Fish bone analysis was used to identify the potential barriers, and four Plan-Do-Study-Act (PDSA) cycles were conducted from January 2021 to March 2021 to address the key barriers. In the first PDSA cycle, training of health care providers was done. Sessions for educating mothers in the second PDSA cycle and individualized one-to-one counseling of mothers by a mother support group were done in the third PDSA cycle. The availability of breast pump was increased in the fourth PDSA cycle. Sustainability of the interventions was studied for 6 months and data were analyzed. Results: The average DHM collected per day at the end of each PDSA cycle was 900, 1,500, 1,000, and 1,100 mL. Although the sustenance phase was affected by the second COVID-19 wave, prompt identification of the issues and timely interventions prevented the donated volume from dropping to preintervention levels. Conclusion: QI initiatives customized for local settings can result in significant improvement in voluntary milk donation in HMB, which can result in more availability of DHM to premature babies.

Breastfeeding vs. breast milk transmission during COVID-19 pandemic, which is more important?

The catastrophic coronavirus disease 2019 (COVID-19) pandemic has raised many health questions, and whether breast milk from SARS-CoV-2 infected mothers may be a vector for SARS-CoV-2 transmission has become a hot topic of concern worldwide. Currently, there are extremely limited and conflicting data on the risk of infection in infants through breastfeeding. For this reason, we investigated almost all current clinical studies and systematically analyzed the presence of SARS-CoV-2 and antibodies in the breast milk of mothers infected with SARS-CoV-2, their effects on newborns, and the mechanisms involved. A total of 82 studies were included in this review, of which 66 examined the presence of SARS-CoV-2 in breast milk samples from mothers diagnosed with COVID-19, 29 reported results of antibody detection of SARS-CoV-2 in breast milk, and 13 reported both nucleic acid and antibody test results. Seventeen studies indicated the presence of detectable SARS-CoV-2 nucleic acid in breast milk samples, and only two studies monitored viral activity, both of which reported that infectious viruses could not be cultured from RNA-positive breast milk samples. All 29 studies indicated the presence of at least one of the three antibodies, IgA, IgG and IgM, in breast milk. Five studies indicated the presence of at least one antibody in the serum of breastfed newborns. No COVID-19-related deaths were reported in all 1,346 newborns. Our study suggests that direct breastfeeding does not pose an additional risk of infection to newborns and that breast milk is a beneficial source of anti-SARS-CoV-2 antibodies that provide passive immune protection to infants. In addition, direct breastfeeding would provide maternal benefits. Our review supports the recommendation to encourage direct breastfeeding under appropriate infection control guidelines. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/#myprospero, identifier: 458043.

Current Advances in Structure-Function Relationships and Dose-Dependent Effects of Human Milk Oligosaccharides

HMOs (human milk oligosaccharides) are the third most important nutrient in breast milk. As complex glycans, HMOs play an important role in regulating neonatal intestinal immunity, resisting viral and bacterial infections, displaying anti-inflammatory characteristics, and promoting brain development. Although there have been some previous reports of HMOs, a detailed literature review summarizing the structure-activity relationships and dose-dependent effects of HMOs is lacking. Hence, after introducing the structures and synthetic pathways of HMOs, this review summarizes and categorizes identified structure-function relationships of HMOs. Differential mechanisms of different structural HMOs utilization by microorganisms are summarized. This review also emphasizes the recent advances in the interactions between different health benefits and the variance of dosage effect based on in vitro cell tests, animal experiments, and human intervention studies. The potential relationships between the chemical structure, the dosage selection, and the physiological properties of HMOs as functional foods are vital for further understanding of HMOs and their future applications.

Mother-to-Child Transmission of HIV Through Breastfeeding Improving Awareness and Education: A Short Narrative Review

Despite critical progress registered in the reduction of mother to child transmission (MTCT) of HIV worldwide, transmission through breastfeeding still contributes to almost 50% of pediatric HIV infections recorded every year. In this short narrative review, after development of an extensive background on HIV and breastfeeding, some directions are suggested to address the key bottlenecks. Specifically, reinforcing the prevention of MTCT through breastfeeding (BF) in order to move towards elimination of MTCT prior to 2030 may require, among others strategies: tracking all women of child bearing age through HIV testing, improving testing and retesting of women during pregnancy and breastfeeding, strengthening adherence on antiretroviral therapy (ART) among pregnant and lactating women, ensuring continuum and retention in care of mother and baby-pairs up to 24 months, switching ART in non-viral suppressed mothers after improvement of adherence counseling. In addition, due to the burden of seroconversion during pregnancy or thereafter through BF, pre-exposure prophylaxis (PreP) for most at risk women should be implemented urgently. The opportunity to extend the infant prophylaxis to the whole lactating period should be assessed to address residual transmission amongst viral suppressed mothers.

Postpartum Mother-To-Child Transmission of HIV in a Breastfeeding Infant

This article is an examination of MTCT of HIV through breastfeeding in a mother who seroconverted postnatally.

SARS-CoV-2 genome and antibodies in breastmilk: a systematic review and meta-analysis

OBJECTIVE

To systematically review and meta-analyse the rate of SARS-CoV-2 genome identification and the presence of SARS-CoV-2 antibodies in breastmilk of mothers with COVID-19.

DESIGN

A systematic review of studies published between January 2019 and October 2020 without study design or language restrictions.

SETTING

Data sourced from Ovid Embase Classic+Embase, PubMed, Web of Science, Scopus, relevant bibliographies and the John Hopkins University COVID-19 database.

PATIENTS

Mothers with confirmed COVID-19 and breastmilk tested for SARS-CoV-2 by RT-PCR or for anti-SARS-CoV-2 antibodies.

MAIN OUTCOME MEASURES

Presence of SARS-CoV-2 genome and antibodies in breastmilk.

RESULTS

We included 50 articles. Twelve out of 183 women from 48 studies were positive for SARS-CoV-2 genome in their breastmilk (pooled proportion 5% (95% CI 2% to 15%; I²=48%)). Six infants (50%) of these 12 mothers tested positive for SARS-CoV-2, with one requiring respiratory support. Sixty-one out of 89 women from 10 studies had anti-SARS-CoV-2 antibody in their breastmilk (pooled proportion 83% (95% CI 32% to 98%; I²=88%)). The predominant antibody detected was IgA.

CONCLUSIONS

SARS-CoV-2 genome presence in breastmilk is uncommon and is associated with mild symptoms in infants. Anti-SARS-CoV-2 antibodies may be a more common finding. Considering the low proportion of SARS-CoV-2 genome detected in breastmilk and its lower virulence, mothers with COVID-19 should be supported to breastfeed.

HIV in pregnancy: Mother-to-child transmission, pharmacotherapy, and toxicity

An estimated 1.3 million pregnant women were living with HIV in 2018. HIV infection is associated with adverse pregnancy outcomes and all HIV-positive pregnant women, regardless of their clinical stage, should receive a combination of antiretroviral drugs to suppress maternal viral load and prevent vertical fetal infection. Although antiretroviral treatment in pregnant women has undoubtedly minimized mother-to-child transmission of HIV, several uncertainties remain. For example, while pregnancy is accompanied by changes in pharmacokinetic parameters, relevant data from clinical studies are lacking. Similarly, long-term adverse effects of exposure to antiretrovirals on fetuses have not been studied in detail. Here, we review current knowledge on HIV effects on the placenta and developing fetus, recommended antiretroviral regimens, and pharmacokinetic considerations with particular focus on placental transport. We also discuss recent advances in antiretroviral research and potential effects of antiretroviral treatment on placental/fetal development and programming.

Correlates of infant feeding practices among HIV-positive mothers and controls in northeast Nigeria

BACKGROUND

Despite the global decline in pediatric HIV infections, infants in sub-Saharan Africa still acquire HIV infection through inappropriate feeding.

OBJECTIVE

The aim of the study was to compare knowledge and predictors of infant feeding behavior between mothers living with HIV and controls of unknown HIV status in Gombe, northeast Nigeria.

METHOD

A cross-section of clinic-based samples of 84 HIV-positive mothers and 170 controls of unknown status were interviewed using validated questionnaires. Knowledge scores and self-reported infant feeding practices were analyzed. Multivariate logistic regression models were employed to determine predictors for infant feeding practices.

RESULTS

Transmission risk perception (95.2% vs. 65.3%) (p<0.05) and adequate knowledge of infant feeding (77.4% vs. 51.2%) (p<0.05) were higher among HIV-positive mothers. Compared to mothers of unknown status (56.5%), a higher proportion of HIV-positive mothers (84.5%) reported breastfeeding the infant exclusively for 6 months (p<0.05). In contrast, mixed feeding was more prevalent among controls (19.4% vs. 4.8%) (p<0.05). Further, over a third (39.3%) of HIV-positive mothers and 27.6% of controls weaned their infants at ≥12 months (p>0.05). Antenatal attendance, hospital delivery, knowledge and positive attitude predicted infant feeding practices in both groups. The predictive roles of education and parity were limited to HIV-positive mothers, while the effects of maternal age and infant death were restricted to controls.

CONCLUSION

Risk perception, knowledge, and exclusive breastfeeding rates were higher among mothers living with HIV. Antenatal care, hospital delivery, knowledge, and attitude predicted infant feeding practices in both groups. Girl child education, antenatal care, hospital delivery, and sustained promotion of exclusive breastfeeding with antiretroviral therapy are key to HIV-free infant survival.

A 6-Country Collaborative Quality Improvement Initiative to Improve Nutrition and Decrease Mother-to-Child Transmission of HIV in Mother-Infant Pairs

Despite advances in coverage and quality of prevention of mother-to-child transmission (PMTCT) programs, infant protection from postnatal HIV infection remains an issue in high HIV-burdened countries. We designed a quality improvement (QI) intervention—the Partnership for HIV-Free Survival (PHFS)—to improve infant survival. PHFS convened leaders in 6 sub-Saharan African nations to discover together the best strategies for implementing and scaling up existing PMTCT protocols to ensure optimal health of mother–baby pairs and HIV-free infant survival. We used 3 core technical components—rapid adaptive design, collaborative learning, and scale-up/sustainability designs—to test strategies for accelerating effective PMTCT programming in complex, resource-poor settings. Learning generated included the need for increased ownership and codesign of improvement initiatives with Ministries of Health, better integration of initiatives into existing programs, and the need to sustain QI capability throughout the system. PHFS can serve as a design prototype for future global networks aiming to accelerate improvement, learning, and results.

Attributes of HIV infection over decades (1982-2018): A systematic review and meta-analysis

Understanding the risk factors for HIV infection is the foundation of successful preventive strategies, which must bundle sociocultural, behavioural and biomedical interventions to halt disease transmission. We aimed in this study to provide a pooled estimation of HIV risk factors and trace changes across decades in order to drive consensus and accurate assessment of disease transmission risk. We comprehensively searched PubMed, ISI Web of Knowledge, Medline, EMBASE, ScienceDirect, Ovid, EBSCO, Google Scholar and the Egyptian Universities Library Consortium from October to December 2018. Two independent reviewers extracted data from eligible studies. Funnel plots were inspected to identify publication bias. Heterogeneity across studies was checked using the Q and I² statistics. The results were reported based on the pooled odds ratio (pOR) with 95% CI using a random-effects model. Meta-analysis of HIV risk factors revealed a superior role for risky sexual practices (unprotected vaginal/anal sex), injecting drug use (IDU), sharing needles, sexually transmitted infections (STIs), child sexual abuse and vertical transmissions. Trends across decades (1982-1999 and 2000-2018, respectively) showed rising evidence for prostitution [pOR (95% CI)= 2.3 (1.12-4.68) versus 2.69 (1.67-4.32)] and men who have sex with men (MSM) [pOR (95% CI)= 2.28 (1.64-3.17) versus 3.67 (1.88-7.17)], while transmission through IDU [pOR (95% CI)= 3.42 (2.28-5.12) versus 2.16 (1.74-2.70)], alcoholism [pOR (95% CI)= 2.35 (0.73-7.59) versus 1.71(1.08-2.72)], and sharing syringes [pOR (95% CI)= 6.10 (2.57-14.5) versus 2.70 (2.01-6.35)] showed notable decline. Harm reduction programs and condom use have been recognized as chief HIV prevention strategies, while male circumcision contributed a partial role. Collectively, sexual risk factors continue to be a key driver of the global HIV epidemic. Persistent and emerging risk factors identified in our analysis should constitute the forefront targets of HIV prevention programmes to accelerate efforts towards HIV elimination.

Women living with HIV in high-income settings and breastfeeding

Guidelines in high-income settings recommend breastfeeding avoidance amongst women living with HIV (WLWH). Increasingly, WLWH in high-income settings, who are well-treated with fully suppressed viral loads, are choosing to breastfeed their infants, even with these recommendations. The purpose of this article is to review existing research and guidance on infant feeding amongst WLWH in high-income countries and to identify gaps in this evidence that require further investigation. Current evidence on the risk of HIV transmission through breastfeeding in the context of antiretroviral therapy (ART), the significance of cell-associated virus, transmission risk factors, retention in care and adherence postpartum, infant prophylaxis and antiretroviral exposure, and monitoring of the breastfeeding WLWH are summarized. A latent HIV reservoir is persistently present in breast milk, even in the context of ART. Thus, suppressive maternal ART significantly reduces, but does not eliminate, the risk of postnatal transmission of HIV. There are currently limited data to guide the optimal frequency of virologic monitoring and the clinical actions to take in case of maternal detectable viral load whilst breastfeeding. Moreover, retention in care and adherence to ART in the postpartum period may be difficult and more research is needed to understand what clinical and psychosocial support would benefit these mothers so that successful engagement in care can be achieved. The long-term effects of antiretroviral drug exposure in the infants also need further exploration. Thus, there is a need for collecting enhanced surveillance data on WLWH who breastfeed and their infants to augment clinical guidance in high-income settings.

Maternal Humoral Immune Responses Do Not Predict Postnatal HIV-1 Transmission Risk in Antiretroviral-Treated Mothers from the IMPAACT PROMISE Study

To design immune interventions that can synergize with antiretroviral therapy (ART) to reduce the rate of HIV mother-to-child transmission (MTCT), it is essential to characterize maternal immune responses in the setting of ART during pregnancy and breastfeeding and define their effect on MTCT. Prior studies reported an association between breast milk envelope (Env)-specific antibodies and antibody-dependent cell cytotoxicity (ADCC) activity with reduced postnatal transmission. In this study, we investigated whether these immune correlates were similarly associated with protection in a matched case-control study of mother-infant pairs receiving maternal ART or infant nevirapine prophylaxis during breastfeeding in the International Maternal-Pediatric-Adolescent AIDS Clinical Trials Network Promoting Maternal-Infant Survival Everywhere (PROMISE) trial, assessing postnatal transmission risk in 19 transmitting and 57 nontransmitting mothers using conditional logistic regression models adjusted for maternal plasma viral load. The odds ratios of postnatal MTCT for a 1-unit increase in an immune correlate were 3.61 (95% confidence interval [CI], 0.56, 23.14) for breast milk Env-specific secretory IgA (sIgA), 2.32 (95% CI, 0.43, 12.56) for breast milk and 2.16 (95% CI, 0.51, 9.14) for plasma Env-specific IgA, and 4.57 (95% CI, 0.68, 30.48) for breast milk and 0.96 (95% CI, 0.25, 3.67) for plasma ADCC activity, with all CIs spanning 1.0. Interestingly, although mucosal IgA responses are poor in untreated HIV-infected women, there was a strong correlation between the magnitudes of breast milk and plasma Env-specific IgA in this cohort. In this analysis of the small number of postnatal virus transmissions in the landmark PROMISE study, no single antibody response was associated with breast milk transmission risk.IMPORTANCE Each year, >150,000 infants become newly infected with HIV-1 through MTCT despite ART, with up to 42% of infections occurring during breastfeeding. Several factors contribute to continued pediatric infections, including ART nonadherence, the emergence of drug-resistant HIV strains, acute infection during breastfeeding, and poor access to ART in resource-limited areas. A better understanding of the maternal humoral immune responses that provide protection against postnatal transmission in the setting of ART is critical to guide the design of maternal vaccine strategies to further eliminate postnatal HIV transmission. In this study, we found that in women treated with antiretrovirals during pregnancy, there was a positive correlation between plasma viral load and breast milk and plasma IgA responses; however, conclusions regarding odds of MTCT risk were limited by the small sample size. These findings will inform future studies to investigate maternal immune interventions that can synergize with ART to eliminate MTCT during breastfeeding.

Effect of bovine leukemia virus on bovine mammary epithelial cells

Bovine leukemia virus (BLV) is a retrovirus that infects cattle and is associated with an increase in secondary infections. The objective of this study was to analyze the effect of BLV infection on cell viability, apoptosis and morphology of a bovine mammary epithelial cell line (MAC-T), as well as Toll like receptors (TLR) and cytokine mRNA expression. Our findings show that BLV infection causes late syncytium formation, a decrease in cell viability, downregulation of the anti-apoptotic gene Bcl-2, and an increase in TLR9 mRNA expression. Moreover, we analyzed how this stably infected cell line respond to the exposure to Staphylococcus aureus (S. aureus), a pathogen known to cause chronic mastitis. In the presence of S. aureus, MAC-T BLV cells had decreased viability and decreased Bcl-2 and TLR2 mRNA expression. The results suggest that mammary epithelial cells infected with BLV have altered the apoptotic and immune pathways, probably affecting their response to bacteria and favoring the development of mastitis.

Determinants of Infant Feeding Practices Among HIV-Infected Mothers in Urban Kano, Nigeria

BACKGROUND

Despite advances in prevention of mother-to-child HIV transmission, infants in Africa remain at risk of HIV acquisition from inappropriate feeding practices.

RESEARCH AIMS

To assess maternal knowledge and predictors of appropriate infant feeding practices among HIV-infected mothers attending a tertiary facility in Kano, Nigeria.

METHOD

A cross section of 203 HIV-positive mothers were interviewed using structured, pretested survey questionnaires. Knowledge scores and infant feeding practices were analyzed. Multivariate logistic regression was employed to ascertain independent correlates of infant feeding practices in the study sample.

RESULTS

Over a third (37.4%) of the participants were aware of the risk of HIV transmission through breastfeeding. The proportion of participants with good, fair, and poor knowledge of recommended feeding options for HIV-exposed infants was 4.4%, 73.4%, and 22.2%, respectively. About three in four participants (73.9%) breastfed their index infants exclusively for the first six months. Approximately 7.4% of respondents practiced mixed feeding (breastfeeding plus infant formula). Counseling on infant feeding (Adjusted Odds Ratio [AOR] = 2.16, 95% Confidence Interval [CI] = [1.58, 4.15]) and hospital delivery (AOR = 3.02, 95% CI = [2.67, 7.84]) predicted appropriate infant feeding practice.

CONCLUSION

Appropriate infant feeding practices were significantly associated with prior infant feeding counseling and delivery in a hospital setting. HIV-infected mothers in this setting should receive counseling on infant feeding early in their pregnancy and be educated on the importance of hospital delivery.

A threshold delay model of HIV infection of newborn infants through breastfeeding

The breast milk of HIV infected women contains HIV virus particles, therefore children can become infected through breastfeeding. We develop a mathematical epidemiological model of HIV infection in infants, infected children and infected women that represents infection of an infant/child as a series of exposures, by incorporating within-host virus dynamics in the individuals exposed to the virus through breastfeeding. We show that repeated exposures of the infant/child via breastfeeding can cause bi-stability dynamics and, subsequently, infection persistence even when the epidemiological basic reproduction number R0 is less than unity. This feature of the model, due to a backward bifurcation, gives new insight into the control mechanisms of HIV disease through breastfeeding.

Cabergoline: a review of its use in the inhibition of lactation for women living with HIV

INTRODUCTION

In developed countries, breastfeeding is not recommended for women living with human immunodeficiency virus (WLWH). However, lactation symptoms can be distressing for women who choose not to breastfeed. There is currently no universal guideline on the most appropriate options for prevention or reduction of lactation symptoms amongst WLWH. This review describes the evidence base for using cabergoline, a dopaminergic agonist, for the post-partum inhibition of lactation for WLWH.

METHODS

A scoping review of post-partum pharmaceutical lactation inhibition specific for WLWH was conducted using searches in PubMed, Medline Ovid, EBM Reviews Ovid, Embase, Web of Science and Scopus until 2019. A narrative review of cabergoline pharmacologic properties, therapeutic efficacy, tolerability data and drug interaction data relevant to lactation inhibition was then conducted.

RESULTS AND DISCUSSION

Among 1366 articles, the scoping review identified 13 relevant publications. Eight guidelines providing guidance regarding lactation inhibition for WLWH and two surveys of medical practice on this topic in UK have been published. Three studies have evaluated the use of pharmaceutical agents in WLWH. Two of these studies evaluated cabergoline and reported it to be an effective method of lactation inhibition in this population. The third study evaluated ethinyl estradiol and bromocriptine use and showed poor efficacy. Cabergoline is a long-acting dopamine D2 agonist and ergot derivative that inhibits prolactin secretion and suppresses physiologic lactation when given as a single oral dose of 1 mg after delivery. Cabergoline is at least as effective as bromocriptine for lactation inhibition with success rates between 78% and 100%. Transient, mild to moderate adverse events to cabergoline are described in clinical trials. Few drug interactions exist as cabergoline is neither a substrate nor an inducer/inhibitor of hepatic cytochrome P450 isoenzymes. There are no reported clinically significant drug-drug interactions between cabergoline and any antiretroviral medications including protease inhibitors.

CONCLUSIONS

Cabergoline is a safe and effective pharmacologic option for the prevention of physiological lactation and associated physical symptoms in non-breastfeeding women. Future studies should focus on its safety, efficacy and acceptability among WLWH.

Managing Mother-to-Child Transmission of HIV Infection in Developed-Country Settings

This article reviews current understanding of the management of mother-to-child transmission of HIV-1 infection in the context of developed-country settings. The advent of highly active antiretroviral therapy has facilitated the virtual elimination of mother-to-child transmission of HIV infection in developed countries, reducing transmission rates to approximately 1–2%. This review describes the epidemiology of HIV infection among women of child-bearing age and the risk factors, timing and mechanisms of mother-to-child transmission, followed by a discussion of the identification of pregnant HIV-infected women and their therapeutic and obstetric management.

Recent Insights into the HIV/AIDS Pandemic

Etiology, transmission and protection: Transmission of HIV, the causative agent of AIDS, occurs predominantly through bodily fluids. Factors that significantly alter the risk of HIV transmission include male circumcision, condom use, high viral load, and the presence of other sexually transmitted diseases. Pathology/Symptomatology: HIV infects preferentially CD4+ T lymphocytes, and Monocytes. Because of their central role in regulating the immune response, depletion of CD4+ T cells renders the infected individual incapable of adequately responding to microorganisms otherwise inconsequential. Epidemiology, incidence and prevalence: New HIV infections affect predominantly young heterosexual women and homosexual men. While the mortality rates of AIDS related causes have decreased globally in recent years due to the use of highly active antiretroviral therapy (HAART) treatment, a vaccine remains an elusive goal. Treatment and curability: For those afflicted HIV infection remains a serious illness. Nonetheless, the use of advanced therapeutics have transformed a dire scenario into a chronic condition with near average life spans. When to apply those remedies appears to be as important as the remedies themselves. The high rate of HIV replication and the ability to generate variants are central to the viral survival strategy and major barriers to be overcome. Molecular mechanisms of infection: In this review, we assemble new details on the molecular events from the attachment of the virus, to the assembly and release of the viral progeny. Yet, much remains to be learned as understanding of the molecular mechanisms used in viral replication and the measures engaged in the evasion of immune surveillance will be important to develop effective interventions to address the global HIV pandemic.

[Use of dried blood spots in early diagnosis of HIV-1 infection in children born to HIV-infected mothers as part of the prevention of mother-to-child transmission in Benin]

The goal of this study was to evaluate using the molecular diagnosis, infection transmission rate of HIV in children born to HIV-1 positive mothers as part of the prevention of mother-to-child transmission (PMTCT) in Benin. The sample consisted of 524 dried blood spots (DBS) of children born to HIV-1 positive mothers, from 30 sites (PMTCT) taken between October 2009 and June 2010. The diagnosis of HIV-1 was performed by the qualitative detection of viral nucleic acids (RNA and DNA) in DBS on filter paper using the Abbott RealTime(®) HIV-1 Qualitative assay. We found that 51 DBS were positive (9.7%) and 473 were negative (90.3%). The failure rate of PMTCT among 420 mothers who received antiretroviral prophylaxis was 6.7% (28/420). This failure rate was significantly higher among children born to infected mothers on antiretroviral monotherapy than on triple therapy (HAART). The results of our study enrich the data in the literature on highly active antiretroviral chemoprophylaxis to reduce the transmission of HIV-1 from mother to child.

Association of HIV-1 Envelope-Specific Breast Milk IgA Responses with Reduced Risk of Postnatal Mother-to-Child Transmission of HIV-1

Infants born to HIV-1-infected mothers in resource-limited areas where replacement feeding is unsafe and impractical are repeatedly exposed to HIV-1 throughout breastfeeding. Despite this, the majority of infants do not contract HIV-1 postnatally, even in the absence of maternal antiretroviral therapy. This suggests that immune factors in breast milk of HIV-1-infected mothers help to limit vertical transmission. We compared the HIV-1 envelope-specific breast milk and plasma antibody responses of clade C HIV-1-infected postnatally transmitting and nontransmitting mothers in the control arm of the Malawi-based Breastfeeding Antiretrovirals and Nutrition Study using multivariable logistic regression modeling. We found no association between milk or plasma neutralization activity, antibody-dependent cell-mediated cytotoxicity, or HIV-1 envelope-specific IgG responses and postnatal transmission risk. While the envelope-specific breast milk and plasma IgA responses also did not reach significance in predicting postnatal transmission risk in the primary model after correction for multiple comparisons, subsequent exploratory analysis using two distinct assay methodologies demonstrated that the magnitudes of breast milk total and secretory IgA responses against a consensus HIV-1 envelope gp140 (B.con env03) were associated with reduced postnatal transmission risk. These results suggest a protective role for mucosal HIV-1 envelope-specific IgA responses in the context of postnatal virus transmission. This finding supports further investigations into the mechanisms by which mucosal IgA reduces risk of HIV-1 transmission via breast milk and into immune interventions aimed at enhancing this response.

IMPORTANCE

Infants born to HIV-1-infected mothers are repeatedly exposed to the virus in breast milk. Remarkably, the transmission rate is low, suggesting that immune factors in the breast milk of HIV-1-infected mothers help to limit transmission. We compared the antibody responses in plasma and breast milk of HIV-1-transmitting and -nontransmitting mothers to identify responses that correlated with reduced risk of postnatal HIV-1 transmission. We found that neither plasma nor breast milk IgG antibody responses were associated with risk of HIV-1 transmission. In contrast, the magnitudes of the breast milk IgA and secretory IgA responses against HIV-1 envelope proteins were associated with reduced risk of postnatal HIV-1 transmission. The results of this study support further investigations of the mechanisms by which mucosal IgA may reduce the risk of HIV-1 transmission via breastfeeding and the development of strategies to enhance milk envelope-specific IgA responses to reduce mother-to-child HIV transmission and promote an HIV-free generation.

Exclusive breastfeeding among women taking HAART for PMTCT of HIV-1 in the Kisumu Breastfeeding Study

Background

One of the most effective ways to promote the prevention of mother-to-child transmission (PMTCT) of HIV-1 in resource-limited settings is to encourage HIV-positive mothers to practice exclusive breastfeeding (EBF) for the first 6 months post-partum while they receive antiretroviral therapy (ARV). Although EBF reduces mortality in this context, its practice has been low. We studied the rate of adherence to EBF and assessed associated maternal and infant characteristics using data from a phase II PMTCT clinical trial conducted in Western Kenya which included a counseling intervention to encourage EBF by all participants.

Methods

We analyzed data from the Kisumu Breastfeeding Study (KiBS), conducted between July 2003 and February 2009. This study enrolled a total of 522 HIV-1 infected pregnant women. Data on breastfeeding were available for 480 mother-infant pairs. Infant feeding and general nutrition counseling began at 35 weeks gestation and continued throughout the 6 month post-partum intervention period, following World Health Organization (WHO) infant feeding guidelines. Data on infant feeding were collected during routine clinic visits and home visits using food frequency questionnaires and dietary recall methods. Participants were instructed to exclusively breastfeed until initiation of weaning at 5.5 months post-partum. We used Kaplan-Meier methods to estimate the rates of EBF at 5.25 months post-partum, stratified by maternal and infant characteristics measured at enrollment, delivery, and 2 weeks post-partum.

Results

The estimated EBF rate at 5.25 months post-partum was 80.4%. Only 3% of women introduced other foods (most commonly water with or without glucose, cow’s milk, formula, and fruit) by 2 months; this percentage increased to 5% of women by 4 months. Women who had ≥3 previous births (p < 0.01) and who were not living with the infant’s father (p = 0.04) were more likely to exclusively breastfeed. Mixed feeding was more common for male infants than for female infants (p = 0.04).

Conclusion

Exclusive breastfeeding was common in this clinical trial, which emphasized EBF as a best practice until infants reached 5.5 months of age. Counseling initiated prior to delivery and continued during the post-partum period provided a consistent message reinforcing the benefits of EBF. The findings from this study suggest high adherence to EBF in resource limited settings can be achieved by a comprehensive counseling intervention that encourages EBF.

Implementation of international code of marketing breast-milk substitutes in China

BACKGROUND

Breastmilk is the best source of nourishment for infants and young children, and breastfeeding is one of the most effective ways to ensure child health and survival. In May 1981, the World Health Assembly adopted the International Code of Marketing Breast-Milk Substitutes. Since then several subsequent resolutions have been adopted by the World Health Assembly, which both update and clarify the articles within the International Code (herein after the term "Code" refers to both the International Code and all subsequent resolutions). The Code is designed to regulate "inappropriate sales promotion" of breastmilk substitutes and instructs signatory governments to ensure the implementation of its aims through legislation. The Chinese Regulations of the Code were adopted by six government sectors in 1995. However, challenges in promotion, protection, and support of breastfeeding remain. This study aimed to monitor the implementation of the Code in China.

SUBJECTS AND METHODS

Six cities were selected with considerable geographic coverage. In each city three hospitals and six stores were surveyed. The International Baby Food Action Network Interview Form was adapted, and direct observations were made. Research assistants administered the questionnaires to a random sample of mothers of infants under 6 months old who were in the outpatient department of the hospitals. In total, 291 mothers of infants, 35 stores, 17 hospitals, and 26 companies were surveyed.

RESULTS

From the whole sample of 291 mothers, the proportion who reported exclusively breastfeeding their infant was 30.9%; 69.1% of mothers reported feeding their infant with commercially available formula. Regarding violations of the Code, 40.2% of the mothers reported receiving free formula samples. Of these, 76.1% received the free samples in or near hospitals. Among the stores surveyed, 45.7% were found promoting products in a way that violates the Code. Also, 69.0% of the labeling on the formula products did not comply with the regulations set out in the Code.

CONCLUSIONS

As the social and economic developments continue, the interactions of more and more factors curb further success in breastfeeding. Support from all sectors of the society is needed in order to create a social environment to enable the promotion of breastfeeding, in addition to the efforts already made by the healthcare system.

Antiretroviral therapy and mother-to-child transmission of HIV-1

The advent of highly active antiretroviral therapy has facilitated the virtual elimination of mother-to-child transmission of HIV infection in developed countries, reducing transmission rates to approximately 1 to 2%. In these settings, highly active antiretroviral therapy has also transformed pediatric HIV infection into a chronic disease; although there are associated costs in terms of side effects and the heavy pill burden. In less developed settings, easier-to-use adaptations of antiretroviral therapy regimens, such as short-course and single-dose antiretroviral strategies or neonatal postexposure prophylaxis can also substantially prevent mother-to-child transmission, although to a lesser degree than highly active antiretroviral therapy. However, postnatal transmission of infection through breastfeeding significantly reduces the longer-term efficacy of these strategies. Ongoing research is focusing on the use of antiretroviral therapy in the breastfeeding period.

Adaptive HIV-specific B cell-derived humoral immune defenses of the intestinal mucosa in children exposed to HIV via breast-feeding

Background

We evaluated whether B cell-derived immune defenses of the gastro-intestinal tract are activated to produce HIV-specific antibodies in children continuously exposed to HIV via breast-feeding.

Methods

Couples of HIV-1-infected mothers (n = 14) and their breastfed non HIV-infected (n = 8) and HIV-infected (n = 6) babies, and healthy HIV-negative mothers and breastfed babies (n = 10) as controls, were prospectively included at the Complexe Pédiatrique of Bangui, Central African Republic. Immunoglobulins (IgA, IgG and IgM) and anti-gp160 antibodies from mother’s milk and stools of breastfed children were quantified by ELISA. Immunoaffinity purified anti-gp160 antibodies were characterized functionally regarding their capacity to reduce attachment and/or infection of R5- and X4- tropic HIV-1 strains on human colorectal epithelial HT29 cells line or monocyte-derived-macrophages (MDM).

Results

The levels of total IgA and IgG were increased in milk of HIV-infected mothers and stools of HIV-exposed children, indicating the activation of B cell-derived mucosal immunity. Breast milk samples as well as stool samples from HIV-negative and HIV-infected babies exposed to HIV by breast-feeding, contained high levels of HIV-specific antibodies, mainly IgG antibodies, less frequently IgA antibodies, and rarely IgM antibodies. Relative ratios of excretion by reference to lactoferrin calculated for HIV-specific IgA, IgG and IgM in stools of HIV-exposed children were largely superior to 1, indicating active production of HIV-specific antibodies by the intestinal mucosa. Antibodies to gp160 purified from pooled stools of HIV-exposed breastfed children inhibited the attachment of HIV-1NDK on HT29 cells by 63% and on MDM by 77%, and the attachment of HIV-1JRCSF on MDM by 40%; and the infection of MDM by HIV-1JRCSF by 93%.

Conclusions

The intestinal mucosa of children exposed to HIV by breast-feeding produces HIV-specific antibodies harbouring in vitro major functional properties against HIV. These observations lay the conceptual basis for the design of a prophylactic vaccine against HIV in exposed children.

A review of human immunodeficiency virus (HIV) and postpartum depression

Depression is common among HIV-infected women, predicts treatment non-adherence, and may impact mother to daughter (vertical) transmission of HIV. A majority of women who develop HIV are of child-bearing age, and are at risk for postpartum depression (PPD). A literature review was performed to analyze the literature regarding PPD in HIV-positive women. This review specifically looked at literature regarding the incidence, risk factors, outcomes, and treatment of PPD in HIV-positive women compared to the general population. While existing literature is limited, it seems to imply that there is no difference between HIV-positive women and unaffected women when it comes to PPD incidence or risk factors. A majority of studies did conclude that routine screenings are needed for depressive symptoms in HIV-positive women.

Cell-free (RNA) and cell-associated (DNA) HIV-1 and postnatal transmission through breastfeeding

INTRODUCTION

Transmission through breastfeeding remains important for mother-to-child transmission (MTCT) in resource-limited settings. We quantify the relationship between cell-free (RNA) and cell-associated (DNA) shedding of HIV-1 virus in breastmilk and the risk of postnatal HIV-1 transmission in the first 6 months postpartum.

MATERIALS AND METHODS

Thirty-six HIV-positive mothers who transmitted HIV-1 by breastfeeding were matched to 36 non-transmitting HIV-1 infected mothers in a case-control study nested in a cohort of HIV-infected women. RNA and DNA were quantified in the same breastmilk sample taken at 6 weeks and 6 months. Cox regression analysis assessed the association between cell-free and cell-associated virus levels and risk of postnatal HIV-1 transmission.

RESULTS

There were higher median levels of cell-free than cell-associated HIV-1 virus (per ml) in breastmilk at 6 weeks and 6 months. Multivariably, adjusting for antenatal CD4 count and maternal plasma viral load, at 6 weeks, each 10-fold increase in cell-free or cell-associated levels (per ml) was significantly associated with HIV-1 transmission but stronger for cell-associated than cell-free levels [2.47 (95% CI 1.33-4.59) vs. aHR 1.52 (95% CI, 1.17-1.96), respectively]. At 6 months, cell-free and cell-associated levels (per ml) in breastmilk remained significantly associated with HIV-1 transmission but was stronger for cell-free than cell-associated levels [aHR 2.53 (95% CI 1.64-3.92) vs. 1.73 (95% CI 0.94-3.19), respectively].

CONCLUSIONS

The findings suggest that cell-associated virus level (per ml) is more important for early postpartum HIV-1 transmission (at 6 weeks) than cell-free virus. As cell-associated virus levels have been consistently detected in breastmilk despite antiretroviral therapy, this highlights a potential challenge for resource-limited settings to achieve the UNAIDS goal for 2015 of eliminating vertical transmission. More studies would further knowledge on mechanisms of HIV-1 transmission and help develop more effective drugs during lactation.

Breast milk cellular HIV-specific interferon γ responses are associated with protection from peripartum HIV transmission

OBJECTIVE

Breast milk is a major route of infant HIV infection, yet the majority of breast-fed, HIV-exposed infants escape infection by unknown mechanisms. This study aimed to investigate the role of HIV-specific breast milk cells in preventing infant HIV infection.

DESIGN

A prospective study was designed to measure associations between maternal breast milk HIV-specific interferon-γ (IFN-γ) responses and infant HIV-1 detection at 1 month of age.

METHODS

In a Kenyan cohort of HIV-infected mothers, blood and breast milk HIV-gag IFN-γ ELISpot responses were measured. Logistic regression was used to measure associations between breast milk IFN-γ responses and infant HIV infection at 1 month of age.

RESULTS

IFN-γ responses were detected in breast milk from 117 of 170 (69%) women. IFN-γ responses were associated with breast milk viral load, levels of macrophage inflammatory protein (MIP) 1α, MIP-1β, regulated upon activation, normal T-cell expressed, and secreted and stromal-cell derived factor 1 and subclinical mastitis. Univariate factors associated with infant HIV infection at 1 month postpartum included both detection and breadth of breast milk IFN-γ response (P = 0.08, P = 0.04, respectively), breast milk MIP-1β detection (P = 0.05), and plasma (P = 0.004) and breast milk (P = 0.004) viral load. In multivariate analyses adjusting for breast milk viral load and MIP-1β, breast milk IFN-γ responses were associated with an approximately 70% reduction in infant HIV infection [adjusted odds ratio (aOR) 0.29, 95% confidence interval (CI) 0.092-0.91], and each additional peptide pool targeted was associated with an approximately 35% reduction in infant HIV (aOR 0.65, 95% CI 0.44-0.97).

CONCLUSION

These data show breast milk HIV-gag-specific IFN-γ cellular immune responses are prevalent and may contribute to protection from early HIV transmission. More broadly, these data suggest breast milk cellular responses are potentially influential in decreasing mother-to-child transmission of viruses.

Prevention of postnatal HIV infection: infant feeding and antiretroviral interventions

PURPOSE OF REVIEW

Mother-to-child transmission of HIV causes most paediatric HIV infections. Short-course peripartum antiretroviral therapy, available in resource-constrained settings, can reduce risk for transmission around the time of delivery. Acceptable, efficient and safe interventions aimed at reducing risk for postnatal HIV transmission through breast milk remain elusive, however.

RECENT FINDINGS

This review summarizes current knowledge on interventions to reduce risk for postnatal transmission of HIV. New information from studies conducted in Africa, where breastfeeding is the norm, suggests that modified infant feeding practices are associated with reduced transmission risk, but women need support as well as appropriate care and nutritional counselling if they are to practise these feeding modes safely. In addition, antiretroviral therapy for HIV-infected breastfeeding mothers is a promising strategy to prevent HIV transmission through breast milk in Africa. The safety and efficacy of this strategy must be assessed within large African longitudinal studies using a variety of antiretroviral regimens.

SUMMARY

Promising interventions to reduce risk for HIV transmission through breast milk do exist, but their implementation at a population level remains insufficient. Development of a safe, effective paediatric preventive HIV vaccine would be an important advance, with a major effect on control of the HIV/AIDS pandemic.

Maternal antiretroviral prophylaxis and breastfeeding

The prevention of mother-to-child transmission of HIV-1 during breastfeeding is a major concern in resource-poor settings where alternatives to breast milk may be unaffordable, unsafe and limited by social stigma. The use of triple-drug antiretroviral regimens initiated during pregnancy and continued throughout breastfeeding is being studied as a means to prevent transmission by reducing HIV-1 viral load in the maternal serum and breast milk. Studies characterizing the exposure of antiretroviral agents in breast milk and in the breastfed infant are important to understand the dynamics of HIV-1 replication in breast milk and to establish the safety profiles of antiretroviral drugs.

HIV-specific antibodies capable of ADCC are common in breastmilk and are associated with reduced risk of transmission in women with high viral loads

There are limited data describing the functional characteristics of HIV-1 specific antibodies in breast milk (BM) and their role in breastfeeding transmission. The ability of BM antibodies to bind HIV-1 envelope, neutralize heterologous and autologous viruses and direct antibody-dependent cell cytotoxicity (ADCC) were analyzed in BM and plasma obtained soon after delivery from 10 non-transmitting and 9 transmitting women with high systemic viral loads and plasma neutralizing antibodies (NAbs). Because subtype A is the dominant subtype in this cohort, a subtype A envelope variant that was sensitive to plasma NAbs was used to assess the different antibody activities. We found that NAbs against the subtype A heterologous virus and/or the woman's autologous viruses were rare in IgG and IgA purified from breast milk supernatant (BMS)--only 4 of 19 women had any detectable NAb activity against either virus. Detected NAbs were of low potency (median IC50 value of 10 versus 647 for the corresponding plasma) and were not associated with infant infection (p = 0.58). The low NAb activity in BMS versus plasma was reflected in binding antibody levels: HIV-1 envelope specific IgG titers were 2.2 log(10) lower (compared to 0.59 log(10) lower for IgA) in BMS versus plasma. In contrast, antibodies capable of ADCC were common and could be detected in the BMS from all 19 women. BMS envelope-specific IgG titers were associated with both detection of IgG NAbs (p = 0.0001) and BMS ADCC activity (p = 0.014). Importantly, BMS ADCC capacity was inversely associated with infant infection risk (p = 0.039). Our findings indicate that BMS has low levels of envelope specific IgG and IgA with limited neutralizing activity. However, this small study of women with high plasma viral loads suggests that breastmilk ADCC activity is a correlate of transmission that may impact infant infection risk.

Human immunodeficiency virus type 1 mother-to-child transmission and prevention: successes and controversies

The World Health Organization (WHO) and United Nations Programme on HIV/AIDS (UNAIDS) estimated that an additional 370 000 new human immunodeficiency virus type 1 (HIV-1) infections occurred in children in 2009, mainly through mother-to-child transmission (MTCT). Intrapartum transmission contributes to approximately 20-25% of infections, in utero transmission to 5-10% and postnatal transmission to an additional 10-15% of cases. MTCT accounts for only a few hundred infected newborns in those countries in which services are established for voluntary counselling and testing of pregnant women, and a supply of antiretroviral drugs is available throughout pregnancy with recommendations for elective Caesarean section and avoidance of breastfeeding. The single-dose nevirapine regimen has provided the momentum to initiate MTCT programmes in many resource-limited countries; however, regimens using a combination of antiretroviral drugs are needed also to effectively reduce transmission via breastfeeding.

Quantifying the impact of nevirapine-based prophylaxis strategies to prevent mother-to-child transmission of HIV-1: a combined pharmacokinetic, pharmacodynamic, and viral dynamic analysis to predict clinical outcomes

Single-dose nevirapine (sd-NVP) and extended NVP prophylaxis are widely used in resource-constrained settings to prevent vertical HIV-1 transmission. We assessed the pharmacokinetics of sd-NVP in 62 HIV-1-positive pregnant Ugandan woman and their newborns who were receiving sd-NVP prophylaxis to prevent mother-to-child HIV-1 transmission. Based on these data, we developed a mathematical model system to quantify the impact of different sd-NVP regimens at delivery and of extended infant NVP prophylaxis (6, 14, 21, 26, 52, 78, and 102 weeks) on the 2-year risk of HIV-1 transmission and development of drug resistance in mothers and their breast-fed infants. Pharmacokinetic parameter estimates and model-predicted HIV-1 transmission rates were very consistent with other studies. Predicted 2-year HIV-1 transmission risks were 35.8% without prophylaxis, 31.6% for newborn sd-NVP, 19.1% for maternal sd-NVP, and 19.7% for maternal/newborn sd-NVP. Maternal sd-NVP reduced newborn infection predominately by transplacental exchange, providing protective NVP concentrations to the newborn at delivery, rather than by maternal viral load reduction. Drug resistance was frequently selected in HIV-1-positive mothers after maternal sd-NVP. Extended newborn NVP prophylaxis further decreased HIV-1 transmission risks, but an overall decline in cost-effectiveness for increasing durations of newborn prophylaxis was indicated. The total number of infections with resistant virus in newborns was not increased by extended newborn NVP prophylaxis. The developed mathematical modeling framework successfully predicted the risk of HIV-1 transmission and resistance development and can be adapted to other drugs/drug combinations to a priori assess their potential in reducing vertical HIV-1 transmission and resistance spread.

The role of HIV replicative fitness in perinatal transmission of HIV

Perinatal transmission of Human immunodeficiency virus (HIV), also called mother-to-child transmission (MTCT), accounts for 90% of infections in infants worldwide and occurs in 30%-45% of children born to untreated HIV-1 infected mothers. Among HIV-1 infected mothers, some viruses are transmitted from mothers to their infants while others are not. The relationship between virologic properties and the pathogenesis caused by HIV-1 remains unclear. Previous studies have demonstrated that one obvious source of selective pressure in the perinatal transmission of HIV-1 is maternal neutralizing antibodies. Recent studies have shown that viruses which are successfully transmitted to the child have growth advantages over those not transmitted, when those two viruses are grown together. Furthermore, the higher fitness is determined by the gp120 protein of the virus envelope. This suggests that the selective transmission of viruses with higher fitness occurred exclusively, regardless of transmission routes. There are many factors contributing to the selective transmission and HIV replicative fitness is an important one that should not be neglected. This review summarizes current knowledge of the role of HIV replicative fitness in HIV MTCT transmission and the determinants of viral fitness upon MTCT.

CD4+ T cells spontaneously producing human immunodeficiency virus type I in breast milk from women with or without antiretroviral drugs

Background

Transmission of human immunodeficiency virus type 1 (HIV-1) through breast-feeding may involve both cell-free and cell-associated virus. This latter viral reservoir remains, however, to be fully explored. CD4⁺ T cell-associated virus production in breast milk was therefore investigated.

Methods

The ex vivo spontaneous production of HIV-1 antigen and HIV-1 RNA by CD4⁺ T cells was measured in paired blood and breast milk samples from 15 HIV-1 infected women treated or not with antiretroviral drugs. Spontaneous antigen secreting cells (HIV-1-AgSCs) from breast milk and blood were enumerated by an ELISpot assay, and cell-associated HIV-1 RNA was quantified by real-time PCR in supernatants of CD4⁺ T cells cultured for 18 hours without addition of polyclonal activators.

Results

Among the CD4⁺ T cells present in breast milk, memory cells expressing high levels of cell-surface activation markers were predominant. Spontaneous HIV-1-AgSCs were detected and enumerated in the breast milk of all 15 women, with a median number of 13.0 and 9.5 HIV-1- AgSCs/106 CD4⁺ T cells in aviremic (n = 7) and viremic (n = 8) women, respectively. Cell- associated HIV-1 RNA was detected in cell-free supernatants from 4/7 aviremic and 5/8 viremic individuals at median levels of 190 and 245 copies/ml, respectively.

Conclusions

Activated CD4⁺ T cells producing HIV-1 are detected in the breast milk of untreated individuals as well as those receiving highly active antiretroviral therapy. This finding strongly suggests that HIV-1 replication occurs in latently infected CD4⁺ T cells that, upon spontaneous activation, revert to productively infected cells. These cells might be responsible for a residual breast milk transmission despite maternal highly active antiretroviral therapy.

Morbidity and mortality among infants born to HIV-infected women in South Africa: implications for child health in resource-limited settings

BACKGROUND

We examined correlates of infant morbidity and mortality within the first 3 months of life among HIV-exposed infants receiving post-exposure antiretroviral prophylaxis in South Africa.

METHODS

We conducted a prospective cohort study of 848 mother-child dyads. Multivariable Cox proportional hazards models were used.

RESULTS

The main causes of infant morbidity were gastrointestinal and respiratory infections. Morbidity was higher with infant HIV infection (HR: 2.61; 95% CI: 1.40-4.85; p = 0.002) and maternal plasma viral load (PVL) >100,000 copies ml⁻¹ (HR: 1.87; 95% CI: 1.01-3.48; p = 0.048), and lower with maternal age < 20 years (HR: 0.25; 95% CI: 0.07-0.88; p = 0.031). Mortality was higher with infant HIV infection (HR: 4.10; 95% CI: 1.18-14.31; p = 0.027) and maternal PVL >100,000 copies ml⁻¹ (HR: 6.93; 95% CI: 1.64-29.26; p = 0.008). Infant feeding status did not influence the risk of morbidity nor mortality.

CONCLUSIONS

Future interventions that minimize pediatric HIV infection and reduce maternal viremia, which are the main predictors of child health soon after birth, will impact positively on infant health outcomes.

Immune-based approaches to the prevention of mother-to-child transmission of HIV-1: active and passive immunization

Despite more than 2 decades of research, an effective vaccine that can prevent HIV-1 infection in populations exposed to the virus remains elusive. In the pursuit of an HIV-1 vaccine, does prevention of exposure to maternal HIV-1 in utero, at birth or in early life through breast milk require special consideration? This article reviews what is known about the immune mechanisms of susceptibility and resistance to mother-to-child transmission (MTCT) of HIV-1 and summarizes studies that have used passive or active immunization strategies to interrupt MTCT of HIV-1. Potentially modifiable infectious cofactors that may enhance transmission and/or disease progression (especially in the developing world) are described. An effective prophylactic vaccine against HIV-1 infection needs to be deployed as part of the Extended Program of Immunization recommended by the World Health Organization for use in developing countries, so it is important to understand how the infant immune system responds to HIV-1 antigens, both in natural infection and presented by candidate vaccines.

Preventing mother to child transmission of HIV with highly active antiretroviral treatment in Tanzania--a prospective cost-effectiveness study

Recent guidelines recommend that all HIV-infected women should receive highly active antiretroviral therapy throughout pregnancy and lactation, irrespective of whether or not they need it for their own health. This strategy for prevention of mother to child transmission (PMTCT) of HIV is more effective than the well-established use of single-dose nevirapine, but it is also a more costly alternative. In this economic evaluation, we use a decision model to combine the best available clinical evidence with cost, epidemiological and behavioral data from Northern Tanzania. We find that a highly active antiretroviral therapy-based PMTCT Plus regimen is more cost effective than the current Tanzanian standard of care with single-dose nevirapine. Although PMTCT Plus is roughly 40% more expensive per pregnant woman than single-dose nevirapine, the expected health benefits are 5.2 times greater. The incremental cost effectiveness ratio of the PMTCT Plus intervention is calculated to be 4062 USD per child infection averted and 162 USD per disability adjusted life year.

The effect of human immunodeficiency virus and breastfeeding on the nutritional status of African children

BACKGROUND

The risk of HIV-1 infection is high among breast-fed children in sub-Saharan Africa. Monitoring the nutritional status can provide useful information to determine the effect of HIV infection and breast-feeding on child growth and development. We longitudinally assessed the nutritional status and determined its association with HIV infection and breast-feeding among Malawian children.

METHODS

We analyzed data from 2 clinical trials to prevent mother-to-child transmission of HIV in Malawi. These trials were conducted during 2000-2003 before the current guidelines were implemented to breast-feed exclusively during the first 6 months and wean thereafter. The nutritional status of children was measured up to age 24 months, using z-scores. Age-specific differences in length-for-age (L/A), weight-for-age (W/A), and weight-for-length (W/L) were compared stratifying by gender and HIV infection status. Multivariable models examined the mean change in z-scores controlling for breast-feeding and other factors.

RESULTS

In this analysis, 1589 children were included. Boys had significantly lower L/A scores and became stunted (z-score -<2 standard deviations) earlier than girls. HIV-infected children had significantly lower mean L/A and W/A z-scores than HIV-uninfected children and became stunted and underweight at an earlier age. In multivariable analysis not being breast-fed and being HIV infected were significantly (P < 0.001) associated with decreases in mean L/A, W/A, and W/L z-scores.

CONCLUSIONS

This study shows the impact of infant HIV infection on growth and supports the critical importance of breast-feeding. Mother-to-child transmission of HIV programs should endeavor to preserve breast-feeding and find alternative measures to prevent postnatal HIV transmission.

Mother-to-child transmission of HIV: a global perspective

HIV-1 infection is a significant global source of childhood morbidity and mortality, and mother-to-child transmission (MTCT) is the major mode of infection. Research over the past two decades has improved our understanding of the pathogenesis of MTCT and pediatric HIV-1 infection, lending to the development of effective preventive and therapeutic strategies. However, successful implementation of these strategies has been limited in resource-constrained settings, where the majority of new pediatric HIV infections now occur. Continued efforts are necessary to better understand MTCT and to refine preventive and therapeutic strategies to allow their successful implementation in the most needed places.

The cost-effectiveness of directly observed highly-active antiretroviral therapy in the third trimester in HIV-infected pregnant women

BACKGROUND

In HIV-infected pregnant women, viral suppression prevents mother-to-child HIV transmission. Directly observed highly-active antiretroviral therapy (HAART) enhances virological suppression, and could prevent transmission. Our objective was to project the effectiveness and cost-effectiveness of directly observed administration of antiretroviral drugs in pregnancy.

METHODS AND FINDINGS

A mathematical model was created to simulate cohorts of one million asymptomatic HIV-infected pregnant women on HAART, with women randomly assigned self-administered or directly observed antiretroviral therapy (DOT), or no HAART, in a series of Monte Carlo simulations. Our primary outcome was the quality-adjusted life expectancy in years (QALY) of infants born to HIV-infected women, with the rates of Caesarean section and HIV-transmission after DOT use as intermediate outcomes. Both self-administered HAART and DOT were associated with decreased costs and increased life-expectancy relative to no HAART. The use of DOT was associated with a relative risk of HIV transmission of 0.39 relative to conventional HAART; was highly cost-effective in the cohort as a whole (cost-utility ratio $14,233 per QALY); and was cost-saving in women whose viral loads on self-administered HAART would have exceeded 1000 copies/ml. Results were stable in wide-ranging sensitivity analyses, with directly observed therapy cost-saving or highly cost-effective in almost all cases.

CONCLUSIONS

Based on the best available data, programs that optimize adherence to HAART through direct observation in pregnancy have the potential to diminish mother-to-child HIV transmission in a highly cost-effective manner. Targeted use of DOT in pregnant women with high viral loads, who could otherwise receive self-administered HAART would be a cost-saving intervention. These projections should be tested with randomized clinical trials.