The largest HIV-1-infected T cell clones in children on long-term combination antiretroviral therapy contain solo LTRs

Combination antiretroviral therapy (cART) suppresses viral replication but does not cure HIV infection because a reservoir of infectious (intact) HIV proviruses persists in long-lived CD4+T cells. However, a large majority (>95%) of HIV-infected cells that persist on effective cART carry defective (non-infectious) proviruses. Defective proviruses consisting of only a single LTR (solo long terminal repeat) are commonly found as endogenous retroviruses in many animal species, but the frequency of solo-LTR HIV proviruses has not been well defined. Here we show that, in five pediatric donors whose viremia was suppressed on cART for at least 5 years, the proviruses in the nine largest clones of HIV-infected cells were solo LTRs. The sizes of five of these clones were assayed longitudinally by integration site-specific quantitative PCR. Minor waxing and waning of the clones was observed, suggesting that these clones are generally stable over time. Our findings show that solo LTRs comprise a large fraction of the proviruses in infected cell clones that persist in children on long-term cART. IMPORTANCE This work highlights that severely deleted HIV-1 proviruses comprise a significant proportion of the proviral landscape and are often overlooked.

Replication-Deficient Zika Vector-Based Vaccine Provides Maternal and Fetal Protection in Mouse Model

Zika virus (ZIKV), a mosquito-borne human pathogen, causes dire congenital brain developmental abnormalities in children of infected mothers. The global health crisis precipitated by this virus has led to a concerted effort to develop effective therapies and prophylactic measures although, unfortunately, not very successfully. The error-prone nature of RNA viral genome replication tends to promote evolution of novel viral strains, which could cause epidemics and pandemics. As such, our objective was to develop a safe and effective replication-deficient ZIKV vector-based vaccine candidate. We approached this by generating a ZIKV vector containing only the nonstructural (NS) 5'-untranslated (UTR)-NS-3' UTR sequences, with the structural proteins capsid (C), precursor membrane (prM), and envelope (E) (CprME) used as a packaging system. We efficiently packaged replication-deficient Zika vaccine particles in human producer cells and verified antigen expression in vitro. In vivo studies showed that, after inoculation in neonatal mice, the Zika vaccine candidate (ZVAX) was safe and did not produce any replication-competent revertant viruses. Immunization of adult, nonpregnant mice showed that ZVAX protected mice from lethal challenge by limiting viral replication. We then evaluated the safety and efficacy of ZVAX in pregnant mice, where it was shown to provide efficient maternal and fetal protection against Zika disease. Mass cytometry analysis showed that vaccinated pregnant animals had high levels of splenic CD8+ T cells and effector memory T cell responses with reduced proinflammatory cell responses, suggesting that endogenous expression of NS proteins by ZVAX induced cellular immunity against ZIKV NS proteins. We also investigated humoral immunity against ZIKV, which is potentially induced by viral proteins present in ZVAX virions. We found no significant difference in neutralizing antibody titer in vaccinated or unvaccinated challenged animals; therefore, it is likely that cellular immunity plays a major role in ZVAX-mediated protection against ZIKV infection. In conclusion, we demonstrated ZVAX as an effective inducer of protective immunity against ZIKV, which can be further evaluated for potential prophylactic application in humans. IMPORTANCE This research is important as it strives to address the critical need for effective prophylactic measures against the outbreak of Zika virus (ZIKV) and outlines an important vaccine technology that could potentially be used to induce immune responses against other pandemic-potential viruses.