New and Hot: Recent Togaviridae Virus Discoveries
2004 - 2005
p32 binding region crucial for rubella virus replication
Scientists at the University of Alberta, Edmonton (Canada) discovered in 2004 that the interaction between rubella virus capsid proteins and p32 (host cell mitochondrial matrix protein) is important for rubella virus replication. Rubella viruses contain a special binding region for the p32 protein. When this region is altered by a mutation of a single nucleotide, the production of rubella virus subgenomic RNA is disrupted. Disruption of the production of rubella virus subgenomic RNA causes a deficit in the amount of structural proteins that the virus can produce. This study helped confirm that rubella viral capsid (particularly the p32 binding region) plays a non-structural role in the regulation of gene expression.
Vector for Venezuelan equine encephalitis discovered
Scientists from the University of Texas Medical Branch set up 6 hampster-baited mosquito traps in Northern Peru to uncover the mosquito species responsible for the tranmssion of Veenezuelan equine encephalitis (VEE). VEE infects humans and other animals near the Amazon in South America, and is a serious public health concern. VEE subtype IIIC alphavirus was found to be transmitted by the Culex (Melanconion) genomatos mosquito. This information will help public health officials target the right mosquito species for vector control against VEE.
Sindbis virus strain is being considered for oncolytic viral therapy for cervical and ovarian cancers
AR339 Sindbis Virus strain was shown to have a cytopathic effect on cervical cancer cells (HeLaS3 and C33A) and ovarian cancer cells (HOC-1, HAC-2, OMC-3) in mice implanted with human tumors. Sindbis virus strain AR339 does not produce any serious illness in humans and is shown to have cytotoxic specificity for cancer cells and not for normal human cells. These features of AR339 make the virus a strong candiate for viral cancer therapy.
Ross River Virus reemergence in Fiji
Two cases of Ross River virus were confirmed in 2004. The virus caused an epidemic in Fiji, American Samoa, Wallis and the Cook Islands betwen 1979-1980, but later disappeared. Appoximately 500,000 people were infected during the outbreak. Two Canadian tourists who travelled to Fiji more recently, in 2003 and 2004, contracted the virus which causes Ross River disease (polyarthritis). Ross River virus is an arbo virus transmitted by Aedes and Culex mosquitos, with marsupials being the most common amplifying host for the virus. The reemergence of Ross River virus disease in humans has prompted public health officials in the regions where the virus is endemic, to strengthen their surveillance of the virus.
Possible DNA Vaccine for western equine encephalitis virus
A DNA vaccine against western equine encephalitis virus (WEEV) was tested in mice and showed promising results. Proteins synthesized by the DNA vaccine (administered intradermally) were sucessful in producing anti-WEEV antibodies in the mice models in addition to elevating levels of cytotoxic T lymphocytes. The vaccine showed levels of protection ranging between 50-100%. WEEV can produce a broad range of disease in humans, from headache to encephalitis, with the most severe cases of disease occuring in young children. WEEV is also transmitted by mosquito vectors, particularly the Culex tarsalis species.
Sources:
Beatch, Everet et al. "Interactions between rubella virus capsid and host protein p32 are important for virus replication." Journal of Virology. August 2005. Vol. 79(17): 10807-20.
Klapsing P, MacLean JD, Glaze S, McClean KL, Drebot MA, Lanciotti RS, et al. "Ross River virus disease reemergence, Fiji, 2003–2004." Emerging Infectious Diseases. [serial on the Internet]. 2005 Apr [date cited]. Available from http://www.cdc.gov/ncidod/EID/vol11no04/04-1070.htm
Negata, Les P. et al. "Efficacy of DNA vaccination against western equine encephalitis virus infection." Vaccine. 18 March 2005. Vol. 23 (17-18): 2280-2283.
Unno Y. et al. "Oncolytic viral therapy for cervical and ovarian cancer cells by Sindbis virus AR339 strain." Clinical Cancer Research. 15 June 2005. Vol. 11(12): 4553-60.
Yanoviak SP. et al. "Transmission of a Venezuelan equine encephalitis comples Alphavirus by Culex (Melanoconion) gnomatos (Diptera: Culicidae) in northeastern Peru." Journal of Medical Entomology. May 2005. Vol. 42(3): 404-8.