Bengaluru: The Hyderabad-based Bharat Biotech that had earlier announced its ambitious plans to produce the zika vaccine in India, has declared the results of the studies on the company’s Zika virus vaccine. The inactivated vaccine has shown 100 percent efficacy against mortality and disease in animal study. The vaccine is based on the killed virus vaccine contains virus that has been grown in culture and then killed certain processes.
Published in the Nature group journal Scientific Reports, the study mentions that the two doses (5 and 10 microgram) of the vaccine given through intramuscular route on days 0 and 21 to mice were found to protect the animals against Zika virus seven days after the second vaccination.
The vaccine was found to confer 100 percent protection against infection caused by an Asian Zika virus strain as well as by the African Zika virus strain. All the animals that were not vaccinated died eight days after infection by the African strain and 12 days after infection by the Asian strain.
While all the animals that received the vaccine exhibited “undetectable” viral load, the amount of virus present in animals that did not receive the vaccine peaked four days after being infected with either the African or Asian Zika virus strain.
Also, the mouse used in the testing was AG129 which is immunocompetent and elicits full spectrum of immune response. Animals that received the vaccine developed Zika-neutralising antibodies on day 14 after the first dose and a week after the second dose.
When the animals were infected with Zika virus post-vaccination, the virus in the vaccinated animals was “undetectable”, while 72-96 hours after infection it peaked in animals that did not receive the vaccine.
The company also carried out passive immunisation studies to show that the Zika vaccine-induced antibodies confer protection against the virus in mice that were exposed to the virus.
Rabbits were vaccinated with the vaccine and the vaccine-induced antibodies were given to mice. While no virus was detected in mice 24-144 hours after passive immunisation, the viral load peaked 72-96 hours in mice that did not receive vaccine-induced antibodies.
The two candidates announced by the company in 2016 included an inactivated vaccine and a recombinant vaccine.