ABSTRACT
Cancer gene therapy based on various gene delivery vectors has some potential but also has obvious disadvantages. In this study, a new M13 phage-based oncolytic virus is constructed that carried the RGD peptides to target tumor cells and the 3C gene of Seneca Valley virus (SVV) preceded by a eukaryotic initial transcriptional region (ITR) to transcribe an oncolytic protein to kill tumor cells. Recombinant virus particles of 1200 nm in length are obtained in large quantities by transfecting the recombinant M13 phage plasmid into the host BL2738 and are investigated in vitro in tumor cells and in vivo in tumor-bearing mice to evaluate their antitumor effect. The experiments using Hela cells confirm that the engineered M13 phage can target and enter Hela cells, and express the SVV 3C protein, resulting in apoptosis of target cells by upregulating the expression of caspase 3. Furthermore, the results of experiments in vivo also show that the recombinant phage significantly inhibits the enhanced tumor volume in nude mice compared to the control groups. The M13 phage may be engineered to fuse with a variety of oncolytic proteins to inhibit the growth of tumor cells in the future, providing a promising phage-based targeted oncolytic reagent.
ABSTRACT
BACKGROUND: Porcine vesicular disease is caused by the Seneca Valley virus (SVV), it is a novel Picornaviridae, which is prevalent in several countries. However, the pathogenicity of SVV on 5-6 week old pigs and the transmission routes of SVV remain unknown. METHODS: This research mainly focuses on the pathogenicity of the CH-GX-01-2019 strain and the possible vector of SVV. In this study, 5-6 week old pigs infected with SVV (CH-GX-01-2019) and its clinical symptoms (including rectal temperatures and other clinical symptoms) were monitored, qRT-PCR were used to detect the viremia and virus distribution. Neutralization antibody assay was set up during this research. Mosquitoes and Culicoides were collected from pigsties after pigs challenge with SVV, and SVV detection within mosquitoes and Culicoides was done via RT-PCR. RESULTS: The challenged pigs presented with low fevers and mild lethargy on 5-8 days post infection. The viremia lasted more than 14 days. SVV was detected in almost all tissues on the 14th day following the challenge, and it was significantly higher in the hoofs (vesicles) and lymph nodes in comparison with other tissues. Neutralizing antibodies were also detected and could persist for more than 28 days, in addition neutralizing antibody titers ranged from 1:128 to 1:512. Mosquitoes and Culicoides were collected from the pigsty environments following SVV infection. Although SVV was not detected in the mosquitoes, it was present in the Culicoides, however SVV could not be isolated from the positive Culicoides. CONCLUSIONS: Our work has enriched the knowledge relating to SVV pathogenicity and possible transmission routes, which may lay the foundation for further research into the prevention and control of this virus.