Flavivirus

Basic information and current topics regarding Flaviviridae

Vaccines and Antivirals

It seems that current generations will be fortunate enough to witness the perfection of flavivirus vaccines. With a good push coming from the World Health Organization (WHO), predominate, disease-causing species of flaviviruses are being neutralized as of today. With about half of the flaviviruses being transmitted by readily available mosquito vectors1, flaviviruses still pose a serious threat to the populations lacking vaccinations.

The development of a safe and effective vaccine for species like West Nile and Dengue Virus seems to have be written on the World Health Organization’s agenda in a permanent marker. As of current, vaccines for Dengue Virus, Japanese Encephalitis Virus, West Nile Virus, and Yellow Fever are all being either developed or administered1. Some vaccines were also developed in the past for flaviviruses, with a successful, live-attenuated Yellow Fever-17D vaccine created in the 1930’s1. However, vaccination for Dengue Virus is not currently being administered as standard practice due to ‘hiccups’ in several trials1.

Trials with experimental Dengue vaccines are on-going, and show progress despite the many set-backs2,3. Many attempts have been made to create deletions in the Dengue genome to create non-infectious viral particles1,2, but it seems that ChimeriVax-DEN-2, a ‘child’ of the YF-17D vaccine, will be beat-out many of these vaccines still in the development-phases.

Developments on a vaccine for the Japanese Encephalitis Virus have succeeded in many trials, and the focus seems to have shifted towards ensuring vaccinations to populations whom desperately need it. Thanks to generous grants from the Bill & Melinda Gates Foundation, the management and monitoring of the distribution of JE vaccine has been made possible1. As presented at a WHO conference on flavivirus vaccine developments, the current JE vaccine has reduced viral encephalitis cases caused by JE from 40% to 15% in studied populations1.

The ChimeriVax-WN02 vaccine for West Nile Virus seems to be in phase II trials currently4. Though, this information is only taken from the article’s abstract–as this author’s academic institution seems to have canceled their Journal of Infectious Diseases subscription in exchange for having a second copy of The Inquirer available.

Alas, all is well. The ball has been passed from the researchers into the hands of the public-health officials. Though many infectious and disease-causing species of flaviviruses still exist today, the giants of this virus family have been tackled. Indeed, we are all very fortunate to witness the development of these vaccines, and all of Human-kind will be forever indebted to the people who have made these critical and miraculous contributions to the World.


References

1. Hombach, J (2005). “Review on flavivirus vaccine development”. Vaccine (0264-410X), 23 (21), p. 2689.

2. Sabchareon, A (02/2004). “Safety and immunogenicity of a three dose regimen of two tetravalent live-attenuated dengue vaccines in five- to twelve-year-old Thai children.”. The Pediatric infectious disease journal (0891-3668), 23 (2), p. 99.

3. Guy, B (01/29/2011). “Dengue vaccine prospects: a step forward.”. The Lancet (British edition) (0140-6736), 377 (9763), p. 381.

4. Biedenbender, R (2011). “Phase II, Randomized, Double-Blind, Placebo-Controlled, Multicenter Study to Investigate the Immunogenicity and Safety of a West Nile Virus Vaccine in Healthy Adults”. The Journal of infectious diseases (0022-1899), 203 (1), p. 75.