Could Cesarean Delivery Help Prevent Mother-to-Child Transmission of Human T-Lymphotropic Virus Type 1?

BACKGROUND: Mother-to-child transmission (MTCT) of human T-lymphotropic virus type 1 (HTLV-1) is an important route of transmission that can cause lifelong infection. There is high morbidity and mortality due to adult T-cell leukemia/lymphoma, HTLV-1-associated myelopathy (HAM), and other inflammatory disorders. These conditions develop in nearly 10% of people with HTLV-1 infection, with a higher risk if infection occurs early in life. Identification of risk factors can inform targeted measures to reduce HTLV-1 MTCT. This study aimed to investigate the potential of cesarean delivery to prevent HTLV-1 MTCT. METHODS: We performed a review of the cases of women and their offspring under regular follow-up at the HTLV-1 outpatient clinic at the Institute of Infectious Diseases Emilio Ribas. RESULTS: A total of 177 HTLV-1-infected women and 369 adult offspring were investigated. Overall, 15% of the children were positive for HTLV-1 and 85% were negative. Regarding vertical transmission, we found that a breastfeeding duration of >6 months was associated with MTCT. Moreover, maternal proviral load was not associated with transmission, but high educational level and cesarean delivery were identified as protective factors. CONCLUSIONS: HTLV-1 MTCT was associated with mother's age at delivery of >25 years, low educational level, prolonged breastfeeding, and vaginal delivery.

Genomic analysis of ERVWE2 locus in patients with multiple sclerosis: absence of genetic association but potential role of human endogenous retrovirus type W elements in molecular mimicry with myelin antigen.

Human endogenous retroviruses (HERVs) arise from ancient infections of the host germline cells by exogenous retroviruses, constituting 8% of the human genome. Elevated level of envelope transcripts from HERVs-W has been detected in CSF, plasma and brain tissues from patients with Multiple Sclerosis (MS), most of them from Xq22.3, 15q21.3, and 6q21 chromosomes. However, since the locus Xq22.3 (ERVWE2) lack the 5' LTR promoter and the putative protein should be truncated due to a stop codon, we investigated the ERVWE2 genomic loci from 84 individuals, including MS patients with active HERV-W expression detected in PBMC. In addition, an automated search for promoter sequences in 20 kb nearby region of ERVWE2 reference sequence was performed. Several putative binding sites for cellular cofactors and enhancers were found, suggesting that transcription may occur via alternative promoters. However, ERVWE2 DNA sequencing of MS and healthy individuals revealed that all of them harbor a stop codon at site 39, undermining the expression of a full-length protein. Finally, since plaque formation in central nervous system (CNS) of MS patients is attributed to immunological mechanisms triggered by autoimmune attack against myelin, we also investigated the level of similarity between envelope protein and myelin oligodendrocyte glycoprotein (MOG). Comparison of the MOG to the envelope identified five retroviral regions similar to the Ig-like domain of MOG. Interestingly, one of them includes T and B cell epitopes, capable to induce T effector functions and circulating Abs in rats. In sum, although no DNA substitutions that would link ERVWE2 to the MS pathogeny was found, the similarity between the envelope protein to MOG extends the idea that ERVEW2 may be involved on the immunopathogenesis of MS, maybe facilitating the MOG recognizing by the immune system. Although awaiting experimental evidences, the data presented here may expand the scope of the endogenous retroviruses involvement on MS pathogenesis.