Reactivation of latent Varicella-Zoster virus (VZV) infection is the cause of shingles, which is prominent in adults over the age of 60 and individuals who have compromised immune systems, due to HIV infection, cancer treatment and/or transplant. Shingles is a worldwide health concern that affects approximately 600,000 Americans each year. The incidence of shingles is also high in Europe, South America, and India; the latter having an estimated two million individuals affected, yearly. Recent research studies show that VZV vaccines have a significant effect on decreasing the incidence of shingles in elderly.

The current technology describes compositions, cells and methods related to the production and use of a mutant VZV and the development of vaccines against the infectious agent. Latent VZV expresses a limited repertoire of viral genes including the following six open reading frames (ORFs): 4, 21, 29, 62, 63, and 66. The present invention describes an ORF29 mutant VZV that demonstrates a weakened ability to establish latency in animal studies. The current technology provides methods for using the mutant in the development of live vaccines and diagnostic tools. A related invention is described in PCT/US05/021788 (publication number WO2006012092).