Inactivation of HIV-1 in breast milk by treatment with the alkyl sulfate microbicide sodium dodecyl sulfate (SDS)

Abstract

Background: Reducing transmission of HIV-1 through breast milk is needed to help decrease the burden of pediatric HIV/AIDS in society. We have previously reported that alkyl sulfates (i.e., sodium dodecyl sulfate, SDS) are microbicidal against HIV-1 at low concentrations, are biodegradable, have little/no toxicity and are inexpensive. Therefore, they may be used for treatment of HIV-1 infected breast milk. In this report, human milk was artificially infected by adding to it HIV-1 (cell-free or cell-associated) and treated with <or=1% SDS (<or=10 mg/ml). Microbicidal treatment was at 37 degrees C or room temperature for 10 min. SDS removal was performed with a commercially available resin. Infectivity of HIV-1 and HIV-1 load in breast milk were determined after treatment.

Results: SDS (>or=0.1%) was virucidal against cell-free and cell-associated HIV-1 in breast milk. SDS could be substantially removed from breast milk, without recovery of viral infectivity. Viral load in artificially infected milk was reduced to undetectable levels after treatment with 0.1% SDS. SDS was virucidal against HIV-1 in human milk and could be removed from breast milk if necessary. Milk was not infectious after SDS removal.

Conclusion: The proposed treatment concentrations are within reported safe limits for ingestion of SDS by children of 1 g/kg/day. Therefore, use of alkyl sulfate microbicides, such as SDS, to treat HIV1-infected breast milk may be a novel alternative to help prevent/reduce transmission of HIV-1 through breastfeeding.

Figure 1

Irreversible inactivation of cell-free HIV-1 in breast milk treated with SDS. A. Breast milk from a healthy donor was artificially infected with cell-free HIV-1 IIIB and treated with 0.1% SDS for up to15 min at 37°C prior to plating on P4-R5 MAGI indicator cells (see methods section for details). Two days later, β-gal expression was measured in relative luminescent units per second (RLU/s) in triplicate samples. Results shown are representative of three experiments. B. Infectivity of cell-free HIV-1 in breast milk treated with SDS (0.05% and 0.1%) was assessed before and after removal of SDS with SDS-300 Detergent-Out™ (see methods section for details). Results are representative of two experiments, each with triplicate samples.

Figure 2

Inactivation of cell-associated HIV-1 in breast milk with SDS. A. Supt-T1 cells infected with HIV-1 IIIB were mixed into breast milk from a healthy donor and treated with 1% or 0.1% SDS for 10 min at 37°C prior to plating on P4-R5 MAGI indicator cells (see methods section for details). Two days later, β-gal expression was measured in relative luminescent units per second (RLU/s) in triplicate samples. Levels of β-gal expression by P4-R5 cells correlates with infectivity of cell-associated HIV-1 (i.e., infected Sup-T1 cells). Results are representative of four experiments. B. Representative results of the time-course of inactivation of cell-associated HIV-1. Sup-T1 cells in media infected with HIV-1 IIIB were treated for up to 15 min with 0.01% SDS and assayed for infectivity using P4-R5 indicator cells. Samples were assayed in triplicate.

Figure 3

Reduction of HIV-1 RNA levels in breast milk treated with SDS. Cell-free HIV-1 IIIB was added to breast milk and treated with ≤1% SDS for 10 min prior to viral load determination using branched DNA technology. Shown are results of 2 independent experiments. Assay sensitivity range: 75–500,000 RNA copies/ml.

Figure 4

Efficiency of SDS removal from breast milk, whole bovine milk and bovine serum albumin. Mixtures of human milk, cow's milk or bovine serum albumin (BSA) containing SDS (0.1%-1%) were subject to SDS removal with SDS-300 Detergent-Out^®, as per manufacturer's instructions. SDS remaining in solution was quantified spectrophotometrically with the reagents included in the SDS-300 Detergent-Out^® kit.