Neutralizing antibodies with neurotropic factor treatment maintain neurodevelopmental gene expression upon exposure to human cytomegalovirus

Abstract

ABSTRACT Human cytomegalovirus (HCMV) is a beta herpesvirus that causes severe congenital birth defects including microcephaly, vision loss, and hearing loss. Entry of HCMV into human cells is determined by the composition of glycoproteins in viral particles and influenced by the source of the virus. We have previously shown that HCMV infection of human stem cell-derived cerebral organoids causes significant downregulation of critical neurodevelopmental genes, but the mechanism of viral entry in human neural tissues is not well known. Here, we evaluated infection efficiency using virus from different sources. We observed significant increases in the number of viral genomes, viral spread and penetrance, and multinucleated syncytia in neural tissues infected with HCMV propagated in epithelial cells compared with fibroblasts. Interestingly, we found similar expression levels of cellular entry receptors on organoid-derived cells suggesting that neural cells do not exhibit a biased entry receptor expression profile. Next, we asked whether we could limit viral entry using neutralization antibodies. We found that pre-treatment with antibodies against viral glycoproteins gB and gH successfully decreased viral genome levels, viral gene expression, and virus-induced syncytia. In contrast, targeting specific cellular entry receptors failed to limit infection. Using an antibody against gB, we observed partial protection of neurodevelopmental gene expression that was further improved by the addition of brain-derived neurotrophic factor (BDNF). These studies indicate that the source of HCMV is a key determinant of viral entry into neuronal cells and combining gB neutralization with BDNF provides further benefit to neural gene expression during infection. IMPORTANCE Human cytomegalovirus (HCMV) infection is the leading cause of non-heritable birth defects worldwide. HCMV readily infects the early progenitor cell population of the developing brain, and we have found that infection leads to significantly downregulated expression of key neurodevelopmental transcripts. Currently, there are no approved therapies to prevent or mitigate the effects of congenital HCMV infection. Therefore, we used human-induced pluripotent stem cell-derived organoids and neural progenitor cells to elucidate the glycoproteins and receptors used in the viral entry process and whether antibody neutralization was sufficient to block viral entry and prevent disruption of neurodevelopmental gene expression. We found that blocking viral entry alone was insufficient to maintain the expression of key neurodevelopmental genes, but neutralization combined with neurotrophic factor treatment provided robust protection. Together, these studies offer novel insight into mechanisms of HCMV infection in neural tissues, which may aid future therapeutic development.