Tricistronic Plasmid Expressing the T7 RNA Polymerase and Measles Virus N and P Proteins for Rescue of Measles Virus AIK-C Strain

: Up to now, several attenuated measles virus vaccine strains derived from the Edmonston B vaccine consisting of Schwarz/Moraten, Zagreb, and AIK-C have been introduced for the rescue of their relative viruses through reverse genetics. In most studies, the measles virus rescue was done by supplying a cell line that expresses T7 RNA polymerase and measles virus N and P proteins as accessory proteins. The present study aimed to evaluate the rescue efficiency of the recombinant measles virus AIK-C vaccine strain by using a tricistronic expression plasmid. In this study, the rescue of the recombinant measles virus AIK-C vaccine strain was performed by co-transfection of three plasmids, including the cloned antigenomic cDNA of measles virus, a tricistronic expression plasmid that contained T7 RNA polymerase and measles virus N and P genes, and measles virus L polymerase expression plasmid. To increase the rescue efficiency, the transfected HEK-293 cells were co-cultured with Vero cells. As a result, the use of tricistronic expression plasmid that concomitantly encoded three necessary genes for the rescue of the measles virus led to the viral cytopathic effect with high efficacy five days post-transfection. Finally, the co-culture of transfected HEK-293 cells with Vero cells showed a relatively fast induction of viral cytopathic effect.

Measles-vectored vaccine approaches against viral infections: a focus on Chikungunya

INTRODUCTION

The large global burden of viral infections and especially the rapidly spreading vector-borne diseases and other emerging viral diseases show the need for new approaches in vaccine development. Several new vaccine technology platforms have been developed and are under evaluation. Areas covered: This article discusses the measles vector platform technology derived from the safe and highly efficacious measles virus vaccine. The pipeline of measles-vectored vaccine candidates against viral diseases is reviewed. Particular focus is given to the Chikungunya vaccine candidate as the first measles-vectored vaccine that demonstrated safety, immunogenicity, and functionality of the technology in humans even in the presence of pre-existing anti-measles immunity and thus achieved proof of concept for the technology. Expert commentary: Demonstrating no impact of pre-existing anti-measles immunity in humans on the response to the transgene was fundamental for the technology and indicates that the technology is suitable for large-scale immunization in measles pre-immune populations. The proof of concept in humans combined with a large preclinical track record of safety, immunogenicity, and efficacy for a variety of pathogens suggest the measles vector platform as promising plug-and-play vaccine platform technology for rapid development of effective preventive vaccines against viral and other infectious diseases.

Recombinant vaccines against the mononegaviruses--what we have learned from animal disease controls

The mononegaviruses include a number of highly contagious and severe disease-causing viruses of both animals and humans. For the control of these viral diseases, development of vaccines, either with classical methods or with recombinant DNA virus vectors, has been attempted over the years. Recently reverse genetics of mononegaviruses has been developed and used to generate infectious viruses possessing genomes derived from cloned cDNA in order to study the consequent effects of viral gene manipulations on phenotype. This technology allows us to develop novel candidate vaccines. In particular, a variety of different attenuation strategies to produce a range of attenuated mononegavirus vaccines have been studied. In addition, because of their ideal nature as live vaccines, recombinant mononegaviruses expressing foreign proteins have also been produced with the aim of developing multivalent vaccines against more than one pathogen. These recombinant mononegaviruses are currently under evaluation as new viral vectors for vaccination. Reverse genetics could have great potential for the preparation of vaccines against many mononegaviruses.