CORRELATION BETWEEN HERPES-SIMPLEX VIRUS TYPE-1 RATE OF REACTIVATION FROM LATENT INFECTION AND THE NUMBER OF INFECTED NEURONS IN TRIGEMINALGANGLIA

The presence of wild-type herpes simplex virus type 1 (HSV-1) and seve ral latency associated transcript (LAT) region mutants within the trig eminal ganglia (TG) of latently infected mice was examined. A combinat ion of methods including conventional in situ hybridization to detect viral LAT and an in situ DNA polymerase chain reaction (PCR) to detect viral DNA was used. These data show that, for all virus strains in wh ich a comparison was possible, the population of neurons expressing de tectable levels of LAT was approximately one-third the total number of viral DNA-containing cells. In addition, in situ PCR analysis reveale d that mutants such as 17 Delta Sty, 17 Delta BstE, and 17 Delta S/N, which contain deletions within the LAT locus which do not affect the k inetics of viral reactivation from explanted murine TG, are present in as many neurons as wild-type virus. This was true regardless of the a bility to induce accumulation of intact 2.0-kb LAT. On the other hand, mutant 17 Delta N/H, which contains a deletion removing tile LAT prom oter and surrounding genomic region and reactivates slowly from explan ted TG, was present in only one-sixth as many neurons as wild-type vir us. These data show that detection of mutants unable to synthesize or accumulate 2.0-kb LAT (such as 17 Delta N/H) is possible with in situ DNA PCR and that the slow reactivation phenotype of 17 Delta N/H corre lates with a reduced number of HSV DNA-containing neurons. (C) 1996 Ac ademic Press, inc.