Increased Cytomegalovirus Secretion and Risks of Infant Infection by Breastfeeding Duration From Maternal Human Immunodeficiency Virus Positive Compared to Negative Mothers in Sub-Saharan Africa

Abstract

BackgroundBreastfeeding imparts beneficial immune protection and nutrition to infants for healthy growth, but it is also a route for human immunodeficiency virus (HIV) and human cytomegalovirus (HCMV) infection. In previous studies, we showed that HCMV adversely affects infant development in Africa, particularly with maternal HIV exposure. In this study, we analyzed infants risks for acquisition of HCMV infection from breastfeeding and compared HIV-positive and HIV-negative mothers.MethodsTwo cohorts were studied in Zambia. (1) Two hundred sixty-one HIV-infected and HIV-uninfected mothers were compared for HCMV deoxyribonucleic acid (DNA) loads and genotypes (glycoprotein gO) in milk from birth to 4 months postpartum. (2) Maternally HIV-exposed and HIV-unexposed infants were compared for HCMV infection risk factors. The second cohort of 460 infants, from a trial of micronutrient-fortified complementary-food to breastfeeding, were studied between 6 and 18 months of age. Human cytomegalovirus seroprevalence was assayed, and logistic regression was used to calculate risk factors for HCMV infection, including maternal HIV exposure and breastfeeding duration.ResultsHuman cytomegalovirus was detected in breast milk from 3 days to 4 months postpartum, with significantly raised levels in HIV-positive women and independent of genotype. In infants, HCMV antibody seroprevalence was 83% by 18 months age. Longer breastfeeding duration increased infection risk in maternally HIV-unexposed (odds ratio [OR] = 2.69 for 18 months vs <12 months; 95% confidence interval [CI], 0.84–8.59; P = .03) and HIV-exposed infants (OR = 20.37 for >6 months vs never; 95% CI, 3.71–111.70; P < .001).ConclusionsProlonged breastfeeding, which is common in Africa, increased risk of HCMV infection in infants. Both HIV-positive and HIV-negative women had extended milk HCMV secretion. Women who were HIV-positive secreted higher HCMV levels, and for longer duration, with their children at increased infection risk. Human cytomegalovirus control is required to maintain health benefits of breastfeeding.

Multiple-Strain Infections of Human Cytomegalovirus with High Genomic Diversity are Common In Breast Milk from HIV-Positive Women in Zambia

“…Our previous study involving Sanger sequencing of single HCMV genes in breast milk samples obtained at multiple time points postpartum pointed to the presence of multiple strains [3]. We extended this by using sequence differences between the genotypes of hypervariable genes across the genome to characterise the strains represented in the datasets.…”

“…We extended this by using sequence differences between the genotypes of hypervariable genes across the genome to characterise the strains represented in the datasets. We focused first on UL73 and UL74, as our earlier work had shown that these adjacent genes are markedly hypervariable, are almost always genotypically linked, and group into eight genotypes also identified in milk samples [3, 7, 12]. The nucleotide sequences were extracted from the set of 243 genome sequences and analysed phylogenetically (Figure 1).…”

“…Anonymised breast milk samples were collected with informed consent as a substudy of the Breast Feeding and Postpartum Health study conducted at the University Teaching Hospital, Lusaka, Zambia, as approved by the ethical committees of the University Teaching Hospital and the London School of Hygiene and Tropical Medicine. This substudy included 28 HCMV-positive breast milk samples donated from one or both breasts by 15 HIV-positive and seven HIV-negative mothers at 4 or 16 weeks (or both) postpartum ( Table 1 and Supplementary Table 1 rows 3-6) [3].…”

“…DNA was extracted from 200 µl breast milk using a QIAamp ® DNA mini kit (QIAGEN, Manchester, UK), and viral DNA load was measured using an in-house HCMV gB TaqMan assay run on an Applied Biosystems ® 7500 fast real-time PCR system (Applied Biosystems, Foster City, CA, USA), as described previously ( Table 1 and Supplementary Table 1 row 7) [3].…”

“…Recent studies have avoided these limitations by using target enrichment to enable direct sequencing of strains present in clinical samples, most of which originated from patients in developed countries with congenital or transplantation-associated infections [11, 22-24]. We have used this approach to examine HCMV strain diversity in a developing country by analysing breast milk from women in Zambia, who constitute an HIV endemic population in sub-Saharan Africa, where we have previously demonstrated the negative developmental effects of early infection of infants with HCMV, particularly alongside HIV exposure [1, 3].…”