The Government College University Lahore Medical Entomologists have successfully genetically modified the Aedes aegypti mosquito in order to block the transmission of dengue viruses to humans. It was announced here on Wednesday by the University's Zoology Department, stating that "the research has good potential to completely eradicate the dengue vectors and viruses from Pakistan, saving thousands of precious lives."
A team of GCU Medical Entomologists, led by Zoology Department former chairperson Professor Dr Nusrat Jahan, have used Wolbachia, a genus of bacteria, as a biological agent for the genetic modification of laboratory reared Aedes aegypti mosquitoes. Wolbachia-based technique makes the mosquito incapable of carrying and transmitting dengue viruses.
The research team also included PhD scholar Muhammad Sajjad Sarwar, MPhil scholars, Falak Batool and Sozaina Khan, and BSc (Hons.) students Zayeema Zainab, Fatima Shahbaz and Ammara Naeem.
The research team explained that they successfully established 21 generations, a locally isolated Wolbachia strain (WAlbB) from wild collected Aedes albopictus mosquitoes in laboratory-reared Aedes aegypti, population by embryo microinjection. "Using Wolbachia based technology the established Wolbachia strain was tested for the potential to suppress Aedes aegypti population and block dengue transmission," they said.
Initially, various strains of Wolbachia were detected with molecular characterisation and isolated from different species of locally collected insects; endosymbiont Wolbachia live naturally in 60% population of insects but not in Aedes aegypti which is a major dengue vector in Pakistan.
"Preliminary data indicated that established WAlbB strain in males Aedes aegypti when mated with non-infected females gave 100% suppression of Aedes aegypti population in laboratory. No progeny hatched in this case due to cytoplasmic incompatibility (CI)," said Professor Nusrat Jahan.
This approach is especially useful for controlling wild population of dengue vector in our environment with mass release of Wolbachia carrying males. Male mosquitoes do not bite or transmit disease. Moreover, other experiments on Aedes aegyti mosquito cell line (developed for the first time in Pakistan in GCU tissue culture lab) and also in caged mosquitoes showed that established Wolbachia reduced the ability of Aedes aegypti mosquitoes to transmit dengue viruses. Laboratory results showed that Wolbachia-carrying female mosquitoes have a lower transmission potential for dengue viruses as, compared to non-Wolbachia carrying mosquitoes.
Professor Jahan said that Wolbachia-carrying Aedes has been released in many countries: such as Australia, Brazil, Indonesia and Vietnam, with no negative impact on public health and ecology. Wolbachia provides a safe strategy, because the bacteria are naturally present in a large population of insects. This is the only novel approach for the sustainable control of dengue disease in Pakistan. This approach is economic (reduced insecticide cost and problem of resistance in vector mosquitoes) and environment friendly.
Professor Jahan said that GCU had conducted the above research in collaboration with Dr Zhiyong Xi, Professor in Michigan State University and Director SYSU-MSU Joint Center of Vector Control for Tropical Diseases, and developed this technology in Pakistan.
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