Varicella-zoster virus (VZV) causes chickenpox and shingles. Virus infection of cells is known to trigger several signaling pathways that are important for cell proliferation and prevention of programmed cell death (also known as apoptosis). We have used a virus genome wide approach to identify functions of VZV proteins. Last year we year we found that VZV triggers the phosphorylation of two proteins, Bim and BAD, that are important for inducing programmed cell death (also known as apoptosis). Phosphorylation of these proteins reduces their ability to cause cell death. VZV-infected cells that were knocked-down for expression of Bim survived longer and produced higher titers of virus compared with wild-type cells infected with the virus. In contrast, VZV-infected cells that overexpressed Bim showed reduced survival and reduced virus replication. Inhibition of caspase activity in cells overexpressing Bim restored levels of virus replication to those seen in wild-type cells. Mammalian cells activate DNA damage response pathways in response to virus infections. H2AX and ATM are activated and recruited to the site of double-stranded DNA breaks and are important for repairing the DNA. Last year we found that VZV-infected cells had elevated levels of phosphorylated H2AX and ATM compared with uninfected cells. Cells infected with VZV deleted for ORF61 or ORF63, but not ORF67, had higher levels of phosphorylated H2AX and ATM compared with cells infected with wild-type virus. Conventional laboratory tests have low sensitivity to detect VZV antibodies in persons who are vaccinated with the varicella vaccine. A high-throughput test to detect varicella-zoster virus (VZV) antibodies in varicella vaccine recipients is not currently available. One of the most sensitive tests for detecting VZV antibodies after vaccination is the fluorescent antibody to membrane antigen (FAMA) test. Unfortunately, this test is labor-intensive, somewhat subjective to read, and not commercially available. This year, we developed a highly quantitative and high-throughput luciferase immunoprecipitation system (LIPS) assay to detect antibody to VZV glycoprotein E (gE). Tests of children who received the varicella vaccine showed that the gE LIPS assay had 90% sensitivity and 70% specificity, a viral capsid antigen enzyme-linked immunosorbent assay (ELISA) had 67% and 87% specificity, and a glycoprotein ELISA (not commercially available in the United States) had 94% sensitivity and 74% specificity compared with the FAMA test. The rates of antibody detection by the gE LIPS and glycoprotein ELISA were not statistically different. Therefore, the gE LIPS assay may be useful for detecting VZV antibodies in varicella vaccine recipients.
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