Study: H3N2 infection, but not vaccine, disrupts H3N2v spread
Neither the seasonal trivalent (three-strain) influenza vaccine (TIV) nor a monovalent H3N2 vaccine substantially reduced shedding of variant H3N2 (H3N2v) virus in ferrets, but previous infection with a seasonal H3N2 virus did, according to a study yesterday in the Journal of Virology.
Researchers from the US Centers for Disease Control and Prevention (CDC) vaccinated 18 ferrets, which are considered good models for flu in humans, with TIV. They also immunized 6 ferrets with one of two monovalent H3N2 vaccines and 3 with an H3N2v monovalent vaccine.
All of the monovalent-vaccinated ferrets and half of the TIV ferrets were then challenged with an H3N2v virus, while the other half of the TIV group was challenged with a seasonal H3N2 strain.
After challenge, the authors checked the seroconversion status of contact ferrets to assess virus shedding. In the TIV group, 6 of 9 contact ferrets converted when exposed to the H3N2v-challenged animals, compared with 4 of 9 in the H3N2-challenged ferrets.
In the monovalent groups, 5 of 6 ferrets that had contact with the H3N2-vaccinated animals seroconverted, compared with none of the 3 ferrets that had contact with the H3N2v-vaccinated animals. Also, all 6 ferrets that had close contact with 6 unvaccinated ferrets that were then either challenged with H3N2 or H3N2v seroconverted.
In the non-vaccine arm of the study, the investigators infected 12 ferrets with a seasonal H3N2 virus. Six weeks later they challenged 6 ferrets with the same seasonal H3N2 strain and 6 with H3N2v.
As expected, 0 of 6 ferrets that had contact with the H3N2-infected animals seroconverted, but similarly only 1 of 6 ferrets that had contact with the H3N2v-infected animals seroconverted, indicating low H3N2v shedding in those ferrets.
The authors conclude, "The data demonstrate in ferrets that the efficiency of A(H3N2)v transmission is disrupted by pre-existing immunity induced by seasonal H3N2 virus infection."
Oct 2 J Virol abstract
DARPA pursuing RNA-based drugs to fight emerging diseases
The US Defense Advanced Research Projects Agency (DARPA) has awarded Moderna Therapeutics of Cambridge, Mass., up to $24.6 million to develop its RNA therapy platform to make antibody-producing drugs that would combat emerging infectious diseases and biological threats, according to a Fierce Biotech story yesterday.
This grant will support research for up to 5 years to advance Moderna's antibody-producing drug candidates into preclinical testing and human clinical trials. In March, DARPA awarded Moderna $700,000 in "seed" funds to begin work on the project.
Moderna's novel platform works by tapping into the body's cells and turning them into antibody producers, a response that could be used to combat a wide range of diseases, the story said.
The grant is part of a DARPA program aimed at developing new platform technologies that could be safely and rapidly deployed to the US population in the event of an infectious disease outbreak like pandemic flu or a biological weapons attack, even if the pathogen or infectious agent were not known.
Oct 2 Fierce Biotech story
In related news, CureVac, of Frankfurt, Germany, which has developed a new class of therapies and vaccines based on messenger RNA, announced today that it will be collaborating with Janssen Pharmaceutical Companies to develop an influenza vaccine based on CureVac's RNActive technology.
RNActive vaccines, based on CureVac's technology platform, have demonstrated safety and effectiveness in several clinical trials, according to a company press release. Preclinical studies were published in Nature Biotechnology in December 2012, CureVac said.
Under the terms of the collaboration, CureVac will develop optimized RNActive vaccines based on proprietary antigen sequences from Crucell Holland B.V. (a Janssen subsidiary) and test them in various models.
Oct 3 CureVac press release