Zika virus transmission via breast milk in suckling mice

Abstract

Objectives: Infectious Zika viral particles were detected in human milk; however, whether they can be transmitted via breastfeeding remains unknown, so our objective was to clarify this.Methods: Here, in a natural breastfeeding model, wild-type (C57Bl/6; WT) or interferon a/b (IFNa/b) receptor-deficient (A129; KO) murine dams on day 1 post-delivery were infected with Zika virus (ZIKV) intraperitoneally, and the neonates were suckled. In a novel artificial feeding model, WT suckling mice at 1 day old were fed with ZIKV alone or ZIKV and human breast milk mixtures. Thereafter, the virus distribution, clinical progression and neuropathology in the WT or KO neonates were characterized to evaluate the risk of ZIKV transmission through breast milk.Results: In natural breastfeeding, viral RNAs (8/8) and infectious viral particles (7/8) were extensively present in the mammary glands of KO dams. All tested KO neonates (5/5), and none of WT neonates (0/ 9), were infected with ZIKV. In artificial feeding, 100% of the WT neonates (two groups, 12/12 and 16/16) were infected and developed some signs of neurodegeneration. ZIKV tended to seed and accumulate in the lungs and were subsequently disseminated to other tissues in both 16 naturally suckled and 19 artificially fed infected neonates. As human breast milk was mixed with ZIKV and fed to WT neonates, 45% individuals (9/20) were infected; in the infected neonates, the viral spread to the brain was delayed, and the clinical outcomes were alleviated. Conclusions: These results demonstrated that suckling mice can be infected with ZIKV through suckling, and breast milk has potential antiviral activity, inhibiting ZIKV infection.

Evidence That Zika Virus Is Transmitted by Breastfeeding to Newborn A129 (Ifnar1 Knock-Out) Mice and Is Able to Infect and Cross a Tight Monolayer of Human Intestinal Epithelial Cells

“…Although the exact nature of ZIKV in breast milk remains unknown, either cell-free, cell-associated, or as extracellular vesicle-cloaked virus clusters, breast milk of some infected mothers was shown to be infectious (Dupont-Rouzeyrol et al, 2016;Blohm et al, 2017;Cavalcanti et al, 2017;Sotelo et al, 2017). Several studies demonstrated that ZIKV viral particles remained infectious in fresh breast milk (Pfaender et al, 2017;Conzelmann et al, 2019) and that potential antiviral properties of breast milk were not sufficient to prevent ZIKV transmission to mice neonates (Pang et al, 2020). These observations led us wonder whether ZIKV could orally infect a suckling child during breastfeeding.…”

“…By exposing lactating dams to a Brazilian strain of ZIKV 3 days after parturition, we noted that 39% of suckling pups became infected. Interestingly, MTCT of another strain of ZIKV (Asian strain) by breastfeeding was recently highlighted (Pang et al, 2020). Because ZIKV had been previously demonstrated to be excreted in murine breast milk, transfer of infectious particles from ZIKV-infected dams to suckling pups via oral swallowing of contaminated breast milk is thus very probable.…”

Anti-Zika virus and anti-Usutu virus activity of human milk and its components

“…While the antiviral activity of HM and its components against numerous viral pathogens have been described in literature, its role in protecting against emerging arboviruses has been poorly PLOS NEGLECTED TROPICAL DISEASES investigated so far [25,58,59]. In this study we addressed this issue focusing on two emerging flaviviruses: we assessed the anti-ZIKV and the anti-USUV activity of human milk in its different stages of maturation and we explored the antiviral contribution of specific components, namely the HM-EVs and the HM-GAGs.…”

“…To the best of our knowledge, this is the first study reporting the intrinsic anti-USUV activity of human milk. On the contrary, Pang et al recently indicated a potential anti-ZIKV action of HM in an artificial feeding model mouse [ 25 ] and other two reports demonstrated that breast milk is able to inactivate ZIKV in a time-dependent manner. These latter studies attributed the antiviral potential to the fat containing cream fraction of human milk, in which the free fatty acids, released upon storage by milk lipases in a time-dependent manner, incorporate into the viral envelope thereby destroying the viral particle [ 30 , 61 ].…”

“…In particular, ZIKV RNA has been reported in breast milk from 3 to 33 days after maternal onset of fever and ZIKV infectious particles were also detected in this biofluid [14][15][16][17][18]. Nevertheless, this mode of transmission to the newborn is still controversial [19][20][21][22][23][24][25]. Probably due to the small number of human cases, the presence Banca d'Italia grant No 0835924/20 (https://www.…”