Human immunodeficiency virus load in breast milk, mastitis, and mother-to-child transmission of human immunodeficiency virus type 1.

Human immunodeficiency virus (HIV) type 1 load in breast milk and mastitis were examined as risk factors for vertical transmission of HIV-1. Six weeks after delivery, HIV-1 load and sodium (an indicator of mastitis) were measured in breast milk from 334 HIV-1-infected women in Malawi. Median breast milk HIV-1 load was 700 copies/mL among women with HIV-1-infected infants versus undetectable (<200 copies/mL) among those with uninfected infants, respectively (P<. 0001). Elevated breast milk sodium levels consistent with mastitis occurred in 16.4% of HIV-1-infected women and were associated with increased vertical transmission of HIV-1 (P<.0001). Median breast milk HIV-1 load was 920 copies/mL among women with versus undetectable among those without elevated breast milk sodium levels, respectively (P<.0001). Mastitis and breast milk HIV-1 load may increase the risk of vertical transmission of HIV-1 through breast-feeding.     

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.     

Risk factors for in utero or intrapartum mother-to-child transmission of human immunodeficiency virus type 1 in Thailand

BACKGROUND: The identification of risk factors for in utero and intrapartum transmission of human immunodeficiency virus type 1 (HIV-1) is crucial to the design and understanding of preventive interventions.METHODS: The randomized Perinatal HIV Prevention Trial-1 enrolled 1437 pregnant women and their non-breast-fed infants, to compare the efficacy of various durations of zidovudine prophylaxis. Using univariate and multivariate logistic regression analyses, we studied the role that factors known or occurring at various times during gestation or delivery play in in utero and intrapartum transmission. RESULTS: Variables independently associated with in utero transmission were HIV-1 load >35,000 copies/mL (adjusted odds ratio [AOR], 4.2) and delayed initiation of maternal zidovudine prophylaxis until >31.4 weeks gestation (AOR, 3.0). Variables associated with intrapartum transmission were HIV-1 load >10,000 copies/mL (AOR, 3.8 for 10,000-35,000 copies/mL and 7.1 for >35,000 copies/mL), induction of labor (AOR, 2.6), and premature labor with tocolysis (AOR, 15.1).CONCLUSIONS: With the exception of very high HIV-1 load, risk factors for in utero transmission were different from those for intrapartum transmission. Optimal prophylactic interventions must address each of the major risk factors, with appropriate timing.     

Correlates of mother-to-child human immunodeficiency virus type 1 (HIV-1) transmission: association with maternal plasma HIV-1 RNA load, genital HIV-1 DNA shedding, and breast infections

To determine the effects of plasma, genital, and breast milk human immunodeficiency virus type 1 (HIV-1) and breast infections on perinatal HIV-1 transmission, a nested case-control study was conducted within a randomized clinical trial of breast-feeding and formula feeding among HIV-1-seropositive mothers in Nairobi, Kenya. In analyses comparing 92 infected infants with 187 infants who were uninfected at 2 years, maternal viral RNA levels >43,000 copies/mL (cohort median) were associated with a 4-fold increase in risk of transmission (95% confidence interval [CI], 2.2-7.2). Maternal cervical HIV-1 DNA (odds ratio [OR], 2.4; 95% CI, 1.3-4.4), vaginal HIV-1 DNA (OR, 2.3; 95% CI, 1.1-4.7), and cervical or vaginal ulcers (OR, 2.7; 95% CI, 1.2-5.8) were significantly associated with infant infection, independent of plasma virus load. Breast-feeding (OR, 1.7; 95% CI, 1.0-2.9) and mastitis (relative risk [RR], 3.9; 95% CI, 1.2-12.7) were associated with increased transmission overall, and mastitis (RR, 21.8; 95% CI, 2.3-211.0) and breast abscess (RR, 51.6; 95% CI, 4.7-571.0) were associated with late transmission (occurring >2 months postpartum). Use of methods that decrease infant exposure to HIV-1 in maternal genital secretions or breast milk may enhance currently recommended perinatal HIV-1 interventions.     

Effect of human immunodeficiency virus (HIV) type 1 viral genotype on mother-to-child transmission of HIV-1

The objective of this study was to determine whether the maternal infecting human immunodeficiency virus (HIV) type 1 clade affects mother-to-child transmission frequency. Mothers in the mother-to-child HIV-1 transmission study in Nairobi, Kenya, were grouped by HIV-1 status of their first enrolled child: uninfected, perinatally infected, or postnatally infected. Restriction fragment length polymorphism (RFLP) analysis was used to determine HIV-1 viral clades of nested polymerase chain reaction products from HIV-1 protease or p24 genes. When inconclusive, sequencing determined the clade. Clade distributions within the groups were compared. The 3 groups displayed a uniform clade distribution. The predominant clades were A (59%) and D (20%). Clades B, C, F, mixed, and recombinant infections comprised the remainder (21%). No significant association was seen between clades A and D and either frequency or mode of vertical transmission. RFLP analysis revealed 2 clade B infections, 9 mixed, and 5 p24/protease recombinant infections in the study population.     

Quantitation of plasma human immunodeficiency virus type 1 RNA by competitive polymerase chain reaction.

Clinical measures of human immunodeficiency virus (HIV) type 1 activity in vivo are limited and hinder the assessment of antiretroviral therapies. Reported here is a method for quantitating HIV-1 RNA in human plasma using the polymerase chain reaction (PCR). This method uses an internal cRNA standard generated from a cloned 113-bp deletion mutation of a highly conserved HIV-1 gag region sequence. The mutant cRNA (K4) was shown to amplify with efficiency equivalent to that of wild-type HIV-1. Known quantities of K4 cRNA added to wild-type HIV-1 in a competitive PCR strategy using a radiolabeled primer permitted quantitation of wild-type HIV-1 RNA over four orders of magnitude (10(3)-10(6) RNA copies). RNA isolated from plasma from AIDS patients yielded 10(3) to 8 x 10(4) HIV-1 RNA copies/ml of plasma with an average intrasample coefficient of variation of .26. This method offers a sensitive assay with a broad dynamic range for monitoring HIV-1 activity in the plasma of AIDS patients. It may provide a useful tool for assessing the effects of antiretroviral therapy.     

Association of plasma levels of human immunodeficiency virus type 1 RNA and oropharyngeal Candida colonization.

The pathophysiology of oropharyngeal candidiasis in patients infected with human immunodeficiency virus (HIV) type 1 is poorly understood. Association between oropharyngeal yeast carriage and various clinical factors in HIV-1-infected patients was studied in 83 patients with no clinical evidence of thrush and no recent antifungal use. Of the clinical factors measured, the only correlate of yeast colonization was with plasma HIV-1 RNA levels (P=.001), whereas the correlation with CD4 cell count was poor (P=.36). By multivariable regression modeling, plasma HIV-1 RNA was the only parameter that correlated with the extent of colonization with Candida infection (P=.003). These data indicate that the presence and amount of asymptomatic oropharyngeal yeast carriage in persons with HIV-1 infection is more significantly correlated with plasma HIV-1 RNA levels than with CD4 cell count. Further studies on the effect of HIV-1 on oropharyngeal yeast colonization, infection, and local immunity are warranted.     

Patterns of plasma human immunodeficiency virus type 1 RNA response to antiretroviral therapy

Early identification of treatment failure among human immunodeficiency virus (HIV) type 1--infected patients receiving antiretroviral therapy could enable clinicians to modify inadequate regimens and to improve treatment response. Clinical definitions of treatment failure, however, may not be ideally suited for this purpose. This study empirically characterizes the patterns of HIV-1 RNA response to antiretroviral therapy in patients in 4 AIDS clinical trials. The approach assumed 2 patterns of HIV-1 response: "on track," for eventual suppression to HIV-1 RNA levels below the limit of quantification, and "off track," for deviation from this response. The results of this on- or off-track classification generally agreed with the protocol-defined outcomes of virologic success and failure, thus validating these commonly used definitions. Overall, only a minority of patients went off track because of suboptimal HIV-1 RNA response by the first follow-up visit. Most patients who went off track did so at later time points and had sharp unexpected rebounds without prior indication of a suboptimal response.     

Adaptive changes after human immunodeficiency virus type 1 transmission

Primary HIV-1 infection (PHI) is associated with a period of viremia, the resolution of which generally coincides with the development of both humoral and cellular immune responses. In this study replication-competent quasispecies were derived from virus isolated from an individual before and after seroconversion. Virus was also isolated from the presumed donor. Phenotypic and genotypic analysis of biological clones identified transmission of an R5/M-tropic phenotype. However, the ability of clones derived from the recipient to replicate in primary macrophages and PBMCs was restricted after transmission. This apparent selection process was supported by analysis of molecular clones derived from the isolated virus. Analysis of the ratio of synonymous and nonsynonymous substitutions predicted the existence of selective pressure soon after transmission, coincident with the development of HIV-1-specific antibodies. An Env trans-complementation assay demonstrated that the infectivity of a clone derived from the recipient after seroconversion was enhanced in the presence of a selected neutralizing antibody, indicating that the developing humoral immune response may have at least in part contributed to the selective pressure identified.     

Quantitation of human immunodeficiency virus type 1 during pregnancy: relationship of viral titer to mother-to-child transmission and stability of viral load.

To develop strategies to prevent mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1), it is important to define the factors determining it. We examined the relationship between maternal HIV-1 titer and the occurrence of mother-to-child transmission. In addition, we quantitated HIV-1 longitudinally in mothers during pregnancy, at delivery, and up to 1 year postpartum. To examine transmission, we prospectively studied 19 mother-child pairs; in 5 pairs, HIV-1 transmission occurred. We used endpoint dilution culture of peripheral blood mononuclear cells to determine maternal viral titer and found that although 4 of 6 (67%) women with viral titers of > or = 125 HIV-1 infectious units per 10(6) cells transmitted HIV-1 to their infants, only 1 of 13 (7.6%) women with lower viral titers transmitted (P = 0.01). Twelve of the 19 mothers had HIV-1 loads determined serially 3-8 times over periods ranging from 18 to 65 weeks. Viral titers varied greatly between the 12 women, but the viral load in each woman remained stable over time. In this cohort, HIV-1 viral load remained stable during pregnancy and the greater the maternal viral burden, the more likely that transmission occurred. These two related findings suggest that determination of HIV-1 titers early in pregnancy may predict which women are at high risk of transmitting to their infants and may be used to counsel HIV-1-infected women of childbearing age. These data identify maternal viral titer as a major determinant of mother-to-child HIV-1 transmission and thereby provide the scientific rationale for therapeutic strategies designed to interrupt transmission by lowering viral load.     

The principal neutralization determinant of simian immunodeficiency virus differs from that of human immunodeficiency virus type 1.

To identify the principal neutralization determinant (PND) of simian immunodeficiency virus (SIV), antisera were generated using recombinant gp110 [the SIV analog of the human immunodeficiency virus type 1 (HIV-1) external envelope glycoprotein, gp120], gp140, several large recombinant and proteolytic envelope fragments, and synthetic peptides of the SIVmac251 isolate. When purified under conditions that retain its native structure, gp110 bound CD4 and elicited antisera that neutralized SIVmac251 with high titer. Native gp110 also completely inhibited neutralizing antibody in sera from SIVmac251-infected macaques. In contrast, denatured gp110 and gp140, large envelope fragments, and synthetic peptides (including peptides analogous to the HIV-1 PND) elicited very low or undetectable neutralizing antibody titers and did not inhibit neutralizing antibody in infected macaque sera. Enzymatically deglycosylated gp110 efficiently absorbed neutralizing antibodies from macaque sera, showing that neutralizing antibodies primarily bind the protein backbone. A 45-kDa protease digest product, mapping to the carboxyl-terminal third of gp110, also completely absorbed neutralizing antibodies from infected macaque sera. These results show that the PND(s) of this SIV isolate depends on the native conformation and that linear peptides corresponding to the V3 loop of SIV envelope, in contrast to that of HIV-1, do not elicit neutralizing antibody. This may affect the usefulness of SIVmac for evaluating HIV-1 envelope vaccine approaches that rely on eliciting neutralizing antibody.     

Changes in plasma human immunodeficiency virus type 1 RNA associated with herpes simplex virus reactivation and suppression

In early trials of antiretroviral therapy, acyclovir was associated with increased survival by an unknown mechanism. The hypothesis that subclinical herpes simplex virus (HSV) reactivation was associated, in vivo, with increased plasma human immunodeficiency virus (HIV) RNA and suppression with a reduced plasma HIV RNA load was investigated. HSV cultures were performed daily on HSV-2-positive/HIV-positive patients, and plasma HIV-1 RNA loads were measured at regular intervals. A subset of patients prior to, during, and after HSV suppression with high-dose acyclovir was measured to determine whether HSV suppression was associated with a decrease in HIV replication. Most (25/27 HSV-2-positive/HIV-positive persons) reactivated HSV. Total HSV shedding rate was strongly correlated with plasma HIV-1 RNA load (R=0.54; P=.004), and the plasma HIV-1 RNA level at a given CD4 cell count was 48% lower when treated with acyclovir. These data indicate that frequent mucosal HSV reactivation influences HIV replication in vivo and daily HSV suppression may be important in the management of HSV-positive/HIV-positive persons.     

Rectal transmission of human immunodeficiency virus type 1 to chimpanzees

Inoculation of chimpanzees with human immunodeficiency virus type 1 (HIV-1) has been used as a model system to define mechanisms of pathogenesis and to test protective efficacy of candidate HIV-1 vaccines. In most of these studies, the animals were inoculated intravenously. However, because HIV-1 is transmitted primarily across mucosal surfaces, future evaluations of vaccines should employ mucosal routes for administering infectious virus to immunized animals. To develop a model of rectal transmission of HIV-1, chimpanzees were exposed without trauma to 4 different HIV-1 strains at doses ranging from 200 to 10,000 TCIDs. Infection, characterized by seroconversion and repeated isolation of virus from lymphocytes, was established in 1 of 5 animals. This animal was sequentially inoculated with a subtype B and then an E strain and was infected with both strains. The results show that rectal exposure of adult chimpanzees to cell-free HIV-1 was not an efficient mode of transmission in this cohort.     

Placental malaria and perinatal transmission of human immunodeficiency virus type 1

Prevalence of placental malaria in human immunodeficiency virus (HIV) type 1-infected and -uninfected women and the effect of placental malaria on genital shedding and perinatal transmission of HIV-1 were examined. Genital samples for HIV-1 DNA RNA were collected during labor. Infants were tested for HIV-1 at 1 day and 6 weeks postpartum. Placental malaria was diagnosed by histopathological examination: 372 placentas of HIV-1-infected women and 277 of HIV-1-uninfected women were processed. A higher prevalence of placental malaria was seen in HIV-1-infected women. No association was found between placental malaria and either maternal virus load, genital HIV-1 DNA, or HIV-1 RNA. Placental malaria did not correlate with in utero or peripartal transmission of HIV-1.     

Maternal HIV-1 DNA load and mother-to-child transmission

While many factors contribute to mother-to-child transmission (MTCT) of HIV-1, maternal plasma HIV-1 RNA viral load (RNA-VL) has been consistently found as the main risk factor, including when antiretroviral prophylaxis was used to prevent MTCT. However the predictive value of RNA-VL is poor. A recent study of HIV-1-positive pregnant women who did not receive antiretroviral prophylaxis reported an association between HIV-1 DNA viral load (DNA-VL) and MTCT that was stronger than the association between RNA-VL and MTCT. We sought to determine if HIV-1 DNA-VL was independently associated with MTCT of HIV in a population of women who received zidovudine prophylaxis during pregnancy and whose infants received zidovudine after birth. Patients were 33 non-breastfeeding transmitting (TR) and 33 nontransmitting mothers (NTR) from Perinatal HIV Prevention Trial (PHPT-1), a multicenter clinical trial conducted in Thailand comparing zidovudine prophylaxis durations to prevent MTCT. TR and NTR mothers were matched according to baseline RNA-VL. Maternal peripheral blood mononuclear cell (PBMC)-associated HIV-1 DNA was extracted from whole blood, and DNA-VL was established by quantitative real-time polymerase chain reaction. We found that TR had a significantly higher cell-associated HIV-1 DNA viral load than did NTR. Median TR DNA-VL was 2.54 log(10) copies per microgram PBMC DNA, while it was 2.28 log(10) copies per microgram PBMC DNA in NTR (Wilcoxon p = 0.02). In summary, HIV-1 DNA viral load was associated with MTCT in a population of women who received antiretroviral prophylaxis during pregnancy, independently from RNA viral load.     

Cofactors in male-female sexual transmission of human immunodeficiency virus type 1

In a study of human immunodeficiency virus type 1 (HIV-1)-uninfected African prostitutes, 83 (67%) of 124 seroconverted to HIV-1. Oral contraceptive use (odds ratio [OR], 3.1; 95% confidence interval [CI], 1.1-8.6; P less than .03), genital ulcers (mean annual episodes, 1.32 +/- 0.55 in seroconverting women vs. 0.48 +/- 0.21 in seronegative women; P less than .02) and Chlamydia trachomatis infections (OR, 3.6; CI, 1.3-11.0; P less than .02) were associated with increased risk of HIV-1 infection. Condom use reduced the risk of HIV-1 infection (OR, 0.11; CI, 0.05-0.27; P less than .0001). Stepwise logistic regression analysis confirmed independent associations between HIV-1 infection and oral contraceptive use, condom use, genital ulcers, and C. trachomatis. The presence of other sexually transmitted diseases may in part explain the heterosexual HIV-1 epidemic in Africa and may represent important targets for intervention to control HIV-1 infection.