Source: Zhongshan School of Medicine
Written by: Zhongshan School of Medicine
Edited by: Wang Dongmei

Guangzhou has witnessed the most serious dengue epidemic in its history.With a total of over 30,000 cases so far, the number of dengue cases in 2014 has exceeded the sum of all its historical cases. However there is no effective vaccine or drug against dengue and the prevention largely relies on the control of Aedesalbopictus, the primary dengue vector in China and secondary in the other countries. Recently an important breakthrough in Wolbachia-based control strategy has been achieved with the joint effort of Sun Yat-sen University, Michigan State University, Chinese Center for Disease Control and Prevention, as well as Guangzhou Center for Disease Control and Prevention.

According to Professor Zhiyong Xi and his colleagues at Sun Yat-sen University - Michigan State University (SYSU-MSU) Joint Center of Vector Control for Tropical Diseases, a native Wolbachia has been successfully isolated from fruit flies, Aedes and Culex mosquitoes, and transferred into Aedes albopictus. As a result, they established several mosquito lines stably carrying different strains of Wolbachia. Such infected male mosquitoes, even when mated with the uninfected female ones, will have no off-springs due to their premature death in the early embryonic development. So theoretically, releasing a sufficient number of Wolbachia-infected male mosquitoes will reduce mosquito population to below a critical threshold necessary for dengue epidemic. 

Further more, Xi and his team discovered that Wolbachia in the infected mosquitoes became resistant to a variety of human pathogens such as dengue virus, yellow fever virus and plasmodium parasites, inhibiting their replication and transmission in those mosquitoes like vaccines. This suggests that dengue transmission can be blocked in the region where mosquitoes are modified with an appropriate Wolbachia infection. Even when dengue was imported from outside epidemic areas, a local dengue transmission or outbreak will unlikely occur.

Consequently, Wolbachia-based strategy is expected to become a revolutionary dengue vector control strategy. By now the Wolbachia-based intervention for dengue control in China has passed the biological safety assessment by the national expert panel, and a field trial permit has been granted by the Ministry of Agriculture. Sun Yat-sen University, Chinese Center for Disease Control and Prevention as well as Guangzhou Center for Disease Control and Prevention will jointly carry out the field trial research.

Due to the profound potentials of this technology in vector-borne disease control, the International Atomic Energy Agency (IAEA) recently established a formal partnership with SYSU-MSU Joint Center of Vector Control for Tropical Diseases and Guangzhou Center for Disease Control and Prevention. The Wolbachia-based dengue control study has been included in the IAEA’s Thematic Plan for the Development and Application of the Sterile Insect Technique (SIT) and Related Genetic and Biological Control Methods for Disease Transmitting Mosquitoes. The field trial in China is currently supported by funds from the TC project jointly sponsored by the Science and Technology Department in Guangdong, the Guangzhou Development Zone, and the Department of Technical Cooperation of IAEA. It is our goal to develop the Wolbachia-based strategy into an efficient tool for dengue control that deserves the WHO recommendation to over 100 countries suffering from the epidemic.