PREPS - HERPES-SIMPLEX VIRUS TYPE 1-SPECIFIC PARTICLES PRODUCED BY INFECTED-CELLS WHEN VIRAL-DNA REPLICATION IS BLOCKED

Herpes simplex virus (HSV)-infected cells produce not only infectious nucleocapsid-containing virions but also virion-related noninfectious light particles (L-particles) composed of the envelope and tegument co mponents of the virus particle (J. F. Szilagvi and C. Cunningham, J. G en, Virol 62:661668, 1991). We show that BHK and MeWO cells infected e ither with wild-type (WT) HSV type 1 (HSV-1) in the presence of viral DNA replication inhibitors (cytosine-beta-D-arabinofuranoside, phospho noacetic acid, and acycloguanosine) or with a viral DNA replication-de fective mutant of HSV-1 (ambUL8) synthesize a new type of virus-relate d particle that is morphologically similar to an L-particle but differ s in its relative protein composition. These novel particles we term p re-viral DNA replication enveloped particles (PREPs). The numbers of P REPs released into the culture medium were of the same order as those of L-particles from control cultures. The particle/PFU ratios of diffe rent PREP stocks ranged from 6 x 10(5) to 3.8 x 10(8), compared with r atios of 3 x 10(3) to 1 x 10(4) for WT L-particle stocks. Sodium dodec yl sulfate-polyacrylamide gel electrophoresis and Western immunoblot a nalyses revealed that true late proteins, such as 273K (VP1-2), 82/81K (VP13/14), and gC (VP8), were greatly reduced or absent in PREPs and that go (VP17) and 40K proteins were also underrepresented. In contras t, the amounts of proteins 175K (VP4; IE3), 92/91K (VP11/12), 38K (VP2 2), and gE (with BHK cells) were increased. The actual protein composi tion of PREPs showed some cell line-dependent differences, particularl y in the amount of gE. PREPs were biologically competent and delivered functional Vmw65 (VP16; alpha TIF) to target cells, but the efficienc y of complementation of the HSV-1 (strain 17) mutant in 1814 was 10 to 30% of that of WT L-particles.