Milk Transmission of Mammalian Retroviruses

Abstract

The transmission of viruses from one host to another typically occurs through horizontal or vertical pathways. The horizontal pathways include transmission amongst individuals, usually through bodily fluids or excretions, while vertical transmission transpires from mother to their offspring, either during pregnancy, childbirth, or breastfeeding. While there are more than 200 human pathogenic viruses to date, only a small number of them are known to be transmitted via breast milk, including cytomegalovirus (CMV), human immunodeficiency virus type 1 (HIV-1), and human T cell lymphotropic virus type 1 (HTLV-1), the latter two belonging to the family Retroviridae. Breast milk transmission is a common characteristic among mammalian retroviruses, but there is a lack of reports summarizing our knowledge regarding this route of transmission of mammalian retroviruses. Here, we provide an overview of the transmission of mammalian exogenous retroviruses with a focus on Orthoretrovirinae, and we highlight whether they have been described or suspected to be transmitted through breast milk, covering various species. We also elaborate on the production and composition of breast milk and discuss potential entry sites of exogenous mammalian retroviruses during oral transmission.

Are Mouse Mammary Tumor Virus and Bovine Leukemia Virus Linked to Breast Cancer among Jordanian Women?

“…It is believed that MMTV may have entered the human population through zoonotic transmission from mice in ancient times and has since been maintained through specific routes of transmission [48]. Two primary routes of transmission documented in the literature include saliva and milk [49]. Studies have detected MMTV DNA in the saliva of BC patients, healthy adults, and children, although not in newborns [50].…”

“…Studies have detected MMTV DNA in the saliva of BC patients, healthy adults, and children, although not in newborns [50]. Moreover, MMTV sequences have been found in the milk of healthy lactating women, as well as in lactating women at high risk of developing BC, indicating another possible route of MMTV transmission among humans [49]. Overall, these findings underscore the need for further research to elucidate the mechanisms of MMTV transmission and its role in BC development, particularly in different geographic regions.…”

The emerging role of the gut virome in necrotizing enterocolitis

“…Breast feeding fosters beneficial bacteria and associated phages, inhibiting eukaryotic viral colonization, while fecal eukaryotic viral loads are higher in formula-fed infants [ 13 , 22 ]. Nonetheless, certain viruses that have infected the mother can be passed on through breastfeeding (e.g., cytomegalovirus, human immunodeficiency virus, and hepatitis B virus) [ 23 , 24 ]. Hospitalized preterm infants are vulnerable to infection and often require antibiotics, which significantly decrease their intestinal microbiota diversity [ 25 ].…”

Infant feeding: emerging concepts to prevent HIV transmission

“…Breast tissue inflammation, including clinical/subclinical mastitis (SCM), also increases transmission risk. Breastmilk transmission may be due to cell-associated or cell-free virus and integrity of infant gut mucosa is an important factor; infections and/or foods, which compromise this may promote transmission [ 9 , 10 ].…”