Identification and DNA sequence analysis of the Marek's disease virus serotype 2 genes homologous to the thymidine kinase and UL24 genes of herpes simplex virus type 1

Mechanism of herpesvirus UL24 protein regulating viral immune escape and virulence

Herpesviruses have evolved a series of abilities involved in the process of host infection that are conducive to virus survival and adaptation to the host, such as immune escape, latent infection, and induction of programmed cell death for sustainable infection. The herpesvirus gene UL24 encodes a highly conserved core protein that plays an important role in effective viral infection. The UL24 protein can inhibit the innate immune response of the host by acting on multiple immune signaling pathways during virus infection, and it also plays a key role in the proliferation and pathogenicity of the virus in the later stage of infection. This article reviews the mechanism by which the UL24 protein mediates herpesvirus immune escape and its effects on viral proliferation and virulence by influencing syncytial formation, DNA damage and the cell cycle. Reviewing these studies will enhance our understanding of the pathogenesis of herpesvirus infection and provide evidence for new strategies to combat against viral infection.

A Thymidine Kinase recombinant protein-based ELISA for detecting antibodies to Duck Plague Virus

BACKGROUND

Duck plague virus (DPV) is the causative agent of Duck Plague (DP) that causes significant morbidity and mortality throughout duck-producing areas of the world. The diagnosis of DP currently relies on the use of live or inactivated whole DPV virion as antigens in ELISA, but it is too laborious and expensive for routine application, and it is still difficult to get purified DPV virion with current technology.

RESULTS

In this study, we describe the expression and purification of a recombinant Thymidine Kinase (TK) protein which makes antigen in an in-house developed, optimized and standardized ELISA. The specificity of the optimized TK-ELISA was evaluated by antisera against Duck Plague Virus (DPV), Duck Hepatitis B Virus (DHBV), Duck Hepatitis Virus (DHV), Riemerella Anatipestifer(R. A), Escherichia coli (E. coli) and Salmonella anatum (S. anatum). Only antisera against DPV yielded a specific and strong signal. In order to determine the sensitivity of the TK-ELISA, a panel of diluted sera was tested, and the minimum detection limit of 1:2560 (OD450 nm = 0.401) was obtained according to the endpoint cut-off (0.2438). The repeatability and reproducibility under the experimental conditions demonstrates a low variability (P > 0.05). The suspected sera samples (n = 30) were determined by TK-ELISA and the positive rate is 90% (27/30), and the TK-ELISA showed 83.33% (22+3/30) coincidence rate with the Serum Neutralization Test (SNT) and 90% (24+3/30) coincidence rate with the whole DPV virion based-ELISA (DPV-ELISA). When defining the dynamics of antibody response to attenuated live DPV vaccine, the maximum antibodies is reached after 4 weeks.

CONCLUSIONS

The results suggest that the TK-ELISA provides high specificity, sensitivity, repeatability and reproducibility for detection of anti-DPV antibodies in duck sera, and has the potential to be much simpler than DPV-ELISA and SNT for the sera epidemiological investigation.

Gene arrangement and RNA transcription of the BamHI fragments K and M2 within the non-oncogenic Marek's disease virus serotype 2 unique long genome region

We determined the nucleotide sequence of a 6593 bp fragment of the Marek's disease virus serotype 2 (MDV2) unique long region located in the right part of genomic BamHI-M2 and the adjacent part of BamHI-K fragments. Within this region five complete open reading frames (ORFs) were identified whose deduced amino acid sequences exhibited homology to the UL53 (glycoprotein K), UL54 (immediate early regulatory protein ICP27), and UL55 gene products of herpes simplex virus type 1 (HSV-1). Homologue to the HSV-1 UL56 was not detected. However, we identified a gene between the MDV2 UL54 and UL55 genes with homology to the first ORF (ORF-1) of equine herpesvirus type 1 and corresponding gene identified in pseudorabies virus. Two adjacent ORFs contained in the BamHI-K fragment, ORF 873s and ORF 873, were found by computer analysis to have the properties of an intron encoding a glycoprotein: ORF 873s encodes a 84 amino acid polypeptide with a stretch of a hydrophobic signal sequence in the C-terminus, and ORF 873 encodes a 873 amino acid polypeptide with a transmembrane domain and putative three N-linked glycosylation sites. All the identified genes were confirmed to be transcribed with 3'-coterminal transcripts and/or a unique transcript in the virus-infected cells. Especially, 3.5 kb mRNA of ORF 873s and ORF 873 are transcribed from a potential promoter region of ORF 873s, and splice donor and acceptor sites are used to splice the mRNA after cleavage of a 113 bp-nucleotide sequence.