Tumor necrosis factor (TNF) has pleiotropic effects on a wide variety of cell types. In vitro studies have demonstrated that TNF has antiviral properties and is induced in response to viral infections. However, a role for TNF in the antiviral immune response of the host has yet to be demonstrated. Here we describe the construction of and studies using a recombinant vaccinia virus that encodes the gene for murine TNF-a. By comparing the replication ofand immune responses elicited by the TNF-encoding virus to a similarly constructed control virus, we hoped to observe immunobiological effects of TNF in the host. The in vivo experiments with this recombinant virus demonstrate that the localized production of TNF-a during a viral infection leads to the rapid and efficient clearance of the virus in normal mice and attenuates the otherwise lethal pathogenicity of the virus in immunodeficient animals.This attenuation occurs early in the infection (by postinfection hour 24) and is not due to the enhancement of cellular or antibody responses by the vaccinia virus-encoded TNF. This evidence suggests that attenuation of the recombinant virus is due to a direct antiviral effect of TNF on cells at the site of infection. Therefore, these results support the suggestion that TNF produced by immune cells may be an important effector mechanism of viral clearance in vivo.

During attempts to establish tissue cultures from hepatopancreas, heart, and hemolymph of the giant tiger prawn (Penaeus monodon), using a medium including penicillin, streptomycin, and amphotericin B, bacterial contamination in the form of a sheet of growth attached to the tissue culture vessel was a persistent problem. Contaminant bacteria were teardrop-shaped cells arranged in rosettes, and electron microscopy revealed buds, crateriform structures, and the absence of a peptidoglycan layer in the cell wall, features characteristic of bacteria in the Planctomyces-Pirellula group, a phylogenetically distinct group of eubacteria. Two strains of contaminant bacteria were isolated in pure culture. Both exhibited morphology and antibiotic resistance consistent with their membership in the Planctomyces-Pirenlula group (order Planctomycetales) of eubacterig. Tissue culture media for marine invertebrates may select for such bacteria if high concentrations of cell wall synthesis-inhibiting antibiotics are included.

A baculovirus of Penaeus plebejus for which we propose the name Plebejus Baculovirus (PBV) was found in postlarval and juvenile P. plebejus from a hatchery and grow-out pond in New South Wales, Australia. Subsphencal eosinophilic inclusion bodies, mostly single or in pairs, were in hypertrophed nuclei of the hepatopancreas and mid-gut epithelia1 cells. Electron microscopy revealed a crystalline lattice of periobcity 20 nm in the inclusion bodies. Vinons up to 440 nm long, both free and occluded in the inclusion body, were scattered in the nuclex. The capsid envelope contained 2 electrondense layers.

Baculovirus particles were found in the digestive gland of Penaeus monodon from hatcheries and grow-out ponds in northern New South Wales, northern Queensland and the Northern Territory. Similar particles were seen in a Penaeus merguiensis specimen caught off Townsville, Queensland. The particles were found in the hypertrophied nuclei of hepatopancreatic epithelial cells, both free in the nucleoplasm and occluded in large eosinophilic intranuclear inclusion bodies. The nucleocapsids of the particles measured 45-52 nm × 260-300 nm and resembled the baculovirus reported from Penaeus plebejus.

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