Immunomodulatory factors in cervicovaginal secretions from pregnant and non-pregnant women: a cross-sectional study.

BACKGROUND: Pregnant women are at an increased risk for HIV infection due to unknown biological causes. Given the strong effect of sex-hormones on the expression of immunomuodulatory factors, the central role of mucosal immunity in HIV pathogenesis and the lack of previous studies, we here tested for differences in immunomuodulatory factors in cervico-vaginal secretions between pregnant and non-pregnant women. METHODS: We compared concentrations of 39 immunomodulatory factors in cervicovaginal lavages (CVL) from 21 pregnant women to those of 24 non-pregnant healthy women from the US. We used Bonferroni correction to correct for multiple testing and linear regression modeling to adjust for possible confounding by plasma cytokine concentration, cervical ectopy, total protein concentration, and other possible confounders. Cervical ectopy was determined by planimetry. Concentration of immunomodulatory factors were measured by a multiplex assay, protein concentration by the Bradford Method. RESULTS: Twenty six (66%) of the 39 measured immunomodulatory factors were detectable in at least half of the CVL samples included in the study. Pregnant women had threefold lower CVL concentration of CCL22 (geometric mean: 29.6 pg/ml versus 89.7 pg/ml, p = 0.0011) than non-pregnant women. CVL CCL22 concentration additionally correlated negatively with gestational age (Spearman correlation coefficient [RS]: -0.49, p = 0.0006). These associations remained significant when corrected for multiple testing. CCL22 concentration in CVL was positively correlated with age and negatively correlated with time since last coitus and the size of cervical ectopy. However, none of these associations could explain the difference of CCL22 concentration between pregnant and non-pregnant women in this study, which remained significant in adjusted analysis. CONCLUSIONS: In this study population, pregnancy is associated with reduced concentrations of CCL22 in cervicovaginal secretions. The role of CCL22 on HIV transmission should now be investigated in prospective studies.

Multiple independent lineages of HIV-1 persist in breast milk and plasma.

DESIGN: the origin and evolution of HIV-1 in breast milk is unclear, despite the continuing significance of this tissue as a transmitting compartment. To elucidate the evolutionary trajectory of viral populations in a transient mucosal compartment, longitudinal sequences of the envelope glycoprotein (gp120) region from plasma and breast milk spanning the first year after delivery were analyzed in six women infected by HIV-1 subtype C. METHODS: multiple phylogenetic algorithms were used to elucidate the evolutionary history and spatial structure of virus populations between tissues. RESULTS: overall persistent mixing of viral sequences between plasma and breast milk indicated that breast milk is not a distinct genetic viral compartment. Unexpectedly, longitudinal phylogenies showed multiple lineages defined by long branches that included virus from both the breast milk and the plasma. Plasma was unlikely the anatomical origin of the most recent common ancestor (MRCA) in at least three of the patients, although in other women, the temporal origin of the MRCA of the viral populations following delivery occurred well before the onset of breast milk production. CONCLUSIONS: these findings suggest that during pregnancy/lactation, a viral variant distinct from the plasma virus initially seeds the breast milk, followed by subsequent gene flow between the plasma and breast milk tissues. This study indicates the potential for reactivation or reintroduction of distinct lineages during major immunological disruptions during the course of natural infection.

4E10-resistant HIV-1 isolated from four subjects with rare membrane-proximal external region polymorphisms.

Human antibody 4E10 targets the highly conserved membrane-proximal external region (MPER) of the HIV-1 transmembrane glycoprotein, gp41, and has extraordinarily broad neutralizing activity. It is considered by many to be a prototype for vaccine development. In this study, we describe four subjects infected with viruses carrying rare MPER polymorphisms associated with resistance to 4E10 neutralization. In one case resistant virus carrying a W680G substitution was transmitted from mother to infant. We used site-directed mutagenesis to demonstrate that the W680G substitution is necessary for conferring the 4E10-resistant phenotype, but that it is not sufficient to transfer the phenotype to a 4E10-sensitive Env. Our third subject carried Envs with a W680R substitution causing variable resistance to 4E10, indicating that residues outside the MPER are required to confer the phenotype. A fourth subject possessed a F673L substitution previously associated with 4E10 resistance. For all three subjects with W680 polymorphisms, we observed additional residues in the MPER that co-varied with position 680 and preserved charged distributions across this region. Our data provide important caveats for vaccine development targeting the MPER. Naturally occurring Env variants described in our study also represent unique tools for probing the structure-function of HIV-1 envelope.

Veterinary field test as screening tool for mastitis and HIV-1 viral load in breastmilk from HIV-infected Zambian women.

Clinical and subclinical mastitis increase the risk of mother-to-child transmission (MTCT) of HIV-1 through breastfeeding. We hypothesized that a field test for mastitis used for bovine milk, the California Mastitis Test, would detect high cell counts in milk of HIV-infected women. We also investigated whether total milk cell count would positively correlate with viral HIV-1 RNA in the milk of 128 HIV-positive Zambian women. Mean cell counts in each California Mastitis Test scoring category were significantly different (p < 0.01, n = 232). In a subset of 4-month postpartum milk samples tested for HIV-1 RNA, viral RNA levels did not significantly correlate with total cell count (r = 0.166, p = .244). The CMT may serve as a screening tool for mastitis in breastmilk, but total cell count does not correlate with HIV-1 RNA levels. Since both cell-free and cell-associated virus are associated with increased risk of MTCT, investigation of the relationship between total milk cell count and HIV-1 proviral DNA is warranted before a conclusive determination is made regarding use of the CMT as a clinical screening tool to detect cases at high risk for breastmilk transmission.