Relative mRNA Expression Levels of Restriction Factors and Antiviral Genes in Fetal and Adult Human Monocytes and Monocyte-Derived Macrophages.

Among untreated HIV-infected pregnant women, the frequency of mother-to-child transmission of HIV is low (5-10%), with most infections occurring at or after birth. Given findings that fetal and adult monocytes are distinct from one another in terms of basal transcriptional profiles, and in phosphorylation of signal transducer and activators of transcription in response to cytokines, we hypothesized that fetal CD14+CD16- monocyte and monocyte-derived macrophages (MDMs) might, compared to their adult counterparts, express higher levels of transcripts for restriction factors and antiviral factors at baseline and/or after stimulation with cytokines that might be induced upon transmission of HIV in utero, for example, IFNα, IFNγ, and IL-6. We carried out these experiments and noted that a few genes, including APOBEC3B, APOBEC3C, and IFITM2, were expressed to a greater degree in fetal monocytes compared to adults. Similarly, the expression levels of APOBEC3F and TRIM32 were greater in fetal MDMs. However, most of these differences were not observed after stimulation with cytokines and the vast majority of antiviral genes were more highly expressed in adults. Therefore, the results of this study are not consistent with the hypothesis that increased expression of antiviral genes in fetal myeloid cells confers immune protection to fetuses in utero.

T-cell Responses in Individuals Infected with Zika Virus and in Those Vaccinated Against Dengue Virus.

BACKGROUND: The outbreak of Zika virus (ZIKV) infection in Brazil has raised concerns that infection during pregnancy could cause microcephaly and other severe neurodevelopmental malformations in the fetus. The mechanisms by which ZIKV causes fetal abnormalities are largely unknown. The importance of pre-infection with dengue virus (DENV), or other flaviviruses endemic to Brazil, remains to be investigated. It has been reported that antibodies directed against DENV can increase ZIKV infectivity by antibody dependent enhancement (ADE), suggesting that a history of prior DENV infection might worsen the outcome of ZIKV infection. METHODS: We used bioinformatics tools to design 18 peptides from the ZIKV envelope containing predicted HLA-I T-cell epitopes and investigated T-cell cross-reactivity between ZIKV-infected individuals and DENV-vaccinated subjects by IFNγ ELISPOT. RESULTS: Three peptides induced IFNγ production in both ZIKV-infected subjects and in DENV-vaccinated individuals. Flow cytometry indicated that 1 ZIKV peptide induced a CD4+ T-cell response in DENV-vaccinated subjects. CONCLUSIONS: We demonstrated that vaccination against DENV induced a T-cell response against ZIKV and identified one such CD4+ T-cell epitope. The ZIKV-reactive CD4+ T cells induced by DENV vaccination and identified in this study could contribute to the appearance of cross-reactive antibodies mediating ADE.

IFITM1 targets HIV-1 latently infected cells for antibody-dependent cytolysis.

HIV-1 persistence in latent reservoirs during antiretroviral therapy (ART) is the main obstacle to virus eradication. To date, there is no marker that adequately identifies latently infected CD4+ T cells in vivo. Using a well-established ex vivo model, we generated latently infected CD4+ T cells and identified interferon-induced transmembrane protein 1 (IFITM1), a transmembrane antiviral factor, as being overexpressed in latently infected cells. By targeting IFITM1, we showed the efficient and specific killing of a latently infected cell line and CD4+ T cells from ART-suppressed patients through antibody-dependent cytolysis. We hypothesize that IFITM1 could mark natural reservoirs, identifying an immune target for killing of latently infected cells. These novel insights could be explored to develop clinical therapeutic approaches to effectively eradicate HIV-1.