By Paddy Shivanand
As of February 1, 2016, the mosquito-borne Zika virus infection was declared a Public Health Emergency of International Concern by the World Health Organization. The increased level of alert that comes with being declared a public health emergency is warranted and perhaps this will begin to address the tremendous coordination needed between governments and private industry to control this particular outbreak. As pointed out in several publications, the definitive link between observation of microcephaly and the viral infection is yet to be scientifically established. It is anticipated that the public health emergency declaration will be the flashpoint needed to renew focus and research resources in understanding whether there is a scientific connection.
Coming so close on the heels of the Ebola virus epidemic, it is indeed disheartening to learn about the possibility of yet another explosive viral epidemic for which there is no cure.
In the absence of a cure, a multi-faceted approach is needed to curb the spread of infection, including evaluation of novel methods of vector control and expediting research into drugs and vaccines that may be available for a potential future outbreak. Successful mosquito control strategies are likely to include the use of mosquito repellents, insecticide-treated bed nets, and the elimination of conditions where mosquitoes thrive, as seen from the decline of malaria in several endemic regions.
An interesting twist to mosquito control is through the use of a transgenic strain of the Aedes aegypti mosquito. In this case, when modified male mosquitoes are released into the wild to mate with female mosquitoes, their offspring will die before reaching adulthood and reproducing themselves. Field trials are ongoing for the viability of using self-limiting mosquitoes to control the wild mosquito population. As pharmaceutical scientists, we routinely work with genetically modified animals in a controlled laboratory setting. However, before releasing the transgenic mosquitoes into nature, an abundance of caution and rigor from the scientific community is needed.
Antiviral drug development for flaviviruses have not yet yielded a successful small molecule drug candidate. Many of the drug design efforts have focused on targeting viral proteases or viral proteins of West Nile and dengue virus. The recent increased research focus from organizations such as the National Institutes of Health on Zika virus can only lead to improved understanding of the viral life cycle, in turn leading to an increased number of targets for antiviral drug discovery and the possibility of a successful drug candidate.
During the last decade, research has intensified into developing vaccines for dengue and West Nile viral infections, leading to the approval of a dengue vaccine in late 2015. Vaccines for both yellow fever and Japanese encephalitis are available, and a vaccine against West Nile is in clinical trials. The track record of success in developing vaccines against several flaviviruses gives us hope that a vaccine could be developed against Zika virus.
An important lesson learned from the Ebola epidemic was the need to bring a sense of speed and urgency to expediting drug and vaccine development and clinical trials for potential treatments.
Can we leapfrog the development of a vaccine against Zika virus based on our collective knowledge and experience gained from vaccine development against other members of the Flaviviridae family? Most people infected with Zika virus can look forward to a full recovery. But for those families that are affected by the birth of a child with microcephaly and accompanying developmental challenges, the economic and emotional price is too high. We owe it to them to speed up the research and bring forth a cure.