Non-axial view of the varicella-zoster virus portal protein reveals conserved crown, wing and clip architecture.

BACKGROUND: Herpesviridae encode a family of protein homologues that function as the 'port of entry' for insertion of the viral DNA into preformed capsids during encapsidation. METHODS: Transmission electron microscopy (TEM) of recombinant varicella-zoster virus pORF54 was performed. RESULTS: Results suggest that pORF54 forms higher-order structures with itself. Enriched fractions analyzed by TEM revealed non-axial oriented portals with defined central channels and distinguishable crown, wing and clip regions. CONCLUSION: These morphological features are consistent with those previously reported for other herpesvirus and bacteriophage portal proteins.

In vitro and in vivo efficacy of a live attenuated Salmonella Typhimurium vaccine at preventing intestinal colonization in chicks.

Vaccination of chicks with Salmonella (S.) Typhimurium aroA deletion mutants has previously been shown to inhibit intestinal colonization of wild-type S. Typhimurium strains. In Australia, Bioproperties VaxSafe™ STM1 strain is the only licensed and commercially available S. Typhimurium vaccine. This vaccine is a live attenuated aroA deletion mutant. Currently, it is recommended that the first dose of the STM1 vaccine is administered through coarse spray. It is unclear whether this mode of administration effectively permits intestinal colonization. Furthermore, it is not known whether the STM1 strain prevents or inhibits Salmonella colonization of chicks following this first dose. This study investigated both in vitro and in vivo colonization parameters. Invasiveness was assessed using an in vitro invasion assay into sections of ileum and caecum collected from day-old chicks. The S. Typhimurium definitive types (DT) 9 and 44 exhibited the greatest invasion into both intestinal segments. STM1 was invasive but was significantly less so than both isolates of S. Typhimurium. In dual and triple infections, no competitive microbial interactions between STM1 and wild-type Salmonella were observed. In vivo colonization inhibition was also tested. Vaccinated and nonvaccinated day-old chicks were challenged with S. Typhimurium DT9. Both STM1 and S. Typhimurium DT9 were found in spleen, liver, ileum, caecum and caecal contents from day 2 postinfection. No significant exclusion effect was observed in vaccinated and challenged chicks.

The Varicella-zoster virus ORF54 gene product encodes the capsid portal protein, pORF54.

The Varicella-zoster virus (VZV) ORF54 gene was characterized using a guinea pig antiserum prepared to a GST-pORF54 fusion protein. A protein of the predicted size, 87kDa, was detected in VZV-infected MeWo cells but not in mock-infected cells. Sucrose density gradient fractionation of pORF54 expressed in a recombinant baculovirus system resulted in samples containing enriched amounts of pORF54. Electron microscopic analysis suggested that the ORF54 gene encodes a protein that assembles into ring-like portal structures similar to those observed for numerous bacteriophages and other herpesviruses.