| Pune |
Updated: April 16, 2018 12:50:30 am
Zika virus is an emerging threat unless it is contained especially in areas where the Aedes aegypti vector is a large number of mosquitoes, including India. At the National Institute of Virology in Pune, scientists have shown in their study how Indian mosquitoes, when infected with the African strain of Zika virus (ZIKV), can easily transmit the infection to suckling mice. In their study published on March 29 this year in Intervirology, a team of scientists from the National Institute of Virology, the National Institute of Leprosy of Jalma and other mycobacterial diseases and other research institutes have shown how the mosquito Aedes aegypti Indian transmitting Dengue virus and chikungunya are easily susceptible to Zika virus.
The director of the NVI, Dr. Devendra Mourya, told The Indian Express, that this study has shown that Indian mosquitoes naturally collect ZIKV. "We have shown their susceptibility when they were injected with ZIKV," he said. Experiments were performed to understand the natural progression of the disease in suckling mice after the bite of mosquitoes infected with ZIKV. "We wanted to see how long it took the virus to replicate: to cross the stomach barrier into the saliva, and through experiments, we discovered that the Indian mosquito … is very susceptible to the Zika virus," Dr. Mourya added.  Mosquitoes were experimentally infected with the Zika virus (African Strain MR-766) through the oral feeding route, which is the natural way by which mosquitoes acquire the virus. Infected mosquitoes were allowed to bite in suckling and lactating mice. The diseased mice were sacrificed and their organs were collected and subjected to three detection tests (RT-PCR in real time, histopathology and immunohistochemistry [IHC]) to verify the presence of the virus.
The results showed clinical symptoms such as tremors, lonely behavior, nervous signs, absence of movement and lethargy appeared in mice after 4-5 days of being bitten by infected mosquitoes. In the terminal stages, the mice became moribund and were then sacrificed. "These [infected] mosquitoes harbor the virus in their salivary glands, which explains their easy transmission when they feed on mice," explained scientist Dr. Pragya Yadav.
In 2013, the first outbreak of Zika virus was reported in the Marquesas Islands in the southern Pacific Ocean. Subsequently, it was extended to Brazil in May 2015. Health agencies in India closely monitored the situation in the country. Three cases identified in Gujarat and one in Chennai did not reveal any travel history to the endemic region of the Zika virus, suggesting that the virus is not new in the country.
In India, more than 35,000 serum samples of febrile disease were analyzed, which produced these four cases, suggesting a very low level of virus transmission. Approximately 18,000 mosquitoes were tested, and this included around 500 Bapunagar mosquitoes in Ahmedabad, where two cases were reported. The virus, however, could not be detected. So far there has been no isolation of this virus. But scientists do not rule out the possibility of mutations that can make these mosquitoes more susceptible to the virus, and lead to a situation similar to an outbreak. In November last year, in the Indian Journal of Medical Research, scientists from the influenza and entomology group of the Indian Council of Medical Research and the National Institute of Virology said that lessons should be learned from the episode when it was suggested that the chikungunya virus had disappeared. of India in 1990-1999.
In 2000, a strain of chikungunya virus that was isolated from mosquitoes in Yawat, Maharashtra, appeared in epidemic form in the Indian Ocean in 2004. Molecular clock studies showed that the epidemic strain originated from Yawat Cepa . Therefore, these lessons can help explain the current low prevalence of Zika virus in India. Like the chikungunya virus, when ZIKV will show a greater affinity for effectively binding to specific virus receptors in the bowels of mosquitoes, it will have the potential to cause outbreaks. The virus does not yet have priority like other flaviviruses such as dengue and chikungunya, said Dr. Mourya.
"There is a need to explore the possibilities of containing the virus, which, in turn, demand advanced knowledge about the natural replication cycle, Our data from this study suggest that mice are highly susceptible to natural infection with this virus. Zika virus strain and, therefore, should be explored as a suitable model to understand the natural transmission of the virus and the progression of the disease, "added the director of the NIV.
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