The number of vector-borne disease cases in the US has tripled over the past decade and these pathogens including mosquito-borne Zika virus (ZIKV) remain an apparent threat to general public health. The ZIKV outbreaks in the Americas and Southeast Asia is a major global health concern, largely due to the association with fetal craniofacial abnormalities and malformations, resulting from prenatal infection. Although ZIKV infection during pregnancy is casually associated with microcephaly, it is important to note that intracranial calcification is the most frequent abnormality present in ZIKV-positive babies. In fact, Magnetic Resonance Imaging study of Brazilian large ZIKV-positive baby cohort reported the intracranial calcifications as the most common clinical observations. While calcification occurs in soft tissues, the abnormal deposition of calcium in brain not only severely affects motor function, speech ability, and vision, but also causes seizures. Despite the growing clinical evidences of ZIKV-induced calcifications and their potential dire outcomes, however, the etiology and molecular mechanisms of ZIKV-induced brain calcification remain elusive. My preliminary observations in ZIKV human fetal brain specimens showed that high level of calcium deposits was localized with virus-infected perivascular cells. Intriguingly, ZIKV-infection of brain perivascular and osteogenic precursor cells robustly induced calcifications in vitro. Surprisingly, the induction of calcification was lineage-specific to the Asian ZIKV strains, but not to the African ZIKV strains. African ZIKV strains rapidly replicated, inducing cell death, while Asian ZIKV strains persistently replicated, leading to aberrant calcium deposition. Surprisingly, ZIKV expression library screen showed that NS3 protease was sufficient to induce calcification. Based on these preliminary data, I hypothesize that ZIKV targets specific host brain perivascular cells and utilizes NS3 protease to induce intracranial calcifications, which ultimately contributes to virus-associated congenital abnormality. Herein, I seek to address the following questions: (i) which host cells are targeted for ZIKV-induced calcifications, and (ii and iii) which and how ZIKV NS3 protease triggers abnormal calcification during infection. This proposal is highly innovative and translational, and potentially shed new insights to ZIKV-induced intracranial calcification that is the most frequent abnormality present in virus-infected babies.
Despite the increasing clinical evidence of intracranial calcifications and craniosynostosis during prenatal ZIKV infection, yet the etiology remains an enigma and is currently unexplored. Herein, I seek to address the molecular mechanisms underlying ZIKV-induced calcifications and resulting craniofacial abnormalities. The insights gained will serve as a preclinical platform for development of therapeutic interventions.
