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NLNK > Newlink shares jump on start of Ebola vaccine study

http://www.marketwatch.com/story/newlink-shares-jump-on-start-of-ebola-vaccine-study-2014-10-13?siteid=yhoof2

SAN FRANCISCO (MarketWatch) -- Shares of Newlink Genetics Corp. NLNK, +21.21% surged Monday after Canadian health officials said they were beginning early-stage clinical trials on an Ebola vaccine that is licensed to the Ames, Iowa-based biotech. Shares of Newlink closed up 24% at $22.42 on heavy volume after the Public Health Agency of Canada said it plans to complete testing in December on whether its vaccine is safe to use in people. The study will be conducted at the Walter Reed Army Institute of Research in Silver Spring, Md.

VSV-EBOV
VSV-EBOV is an experimental vaccine for the Ebola filovirus, developed by scientists at the Canadian National Microbiology Laboratory.[1][2] VSV-EBOV is based on the vesicular stomatitis virus, which has been genetically engineered to express Ebola glycoproteins so as to provoke an immune response against real Ebola virus. The vaccine variant known as rVSV-ZEBOV, rVSV-ZEBOV-GP, VSV?G-ZEBOV, or BPSC1001 expresses glycoproteins of the Zaire ebolavirus or ZEBOV, the species causing the highest mortality rate among the ebolaviruses, while rVSV-MARV or rVSV-MARV-GP expresses those of the closely related Marburg filovirus or MARV. A single intramuscular injection of the EBOV or MARV vaccine induced completely protective immune responses in nonhuman primates (crab-eating macaques) against corresponding infections with the otherwise typically lethal EBOV or MARV.[3][4] Also, the vaccination itself did not induce any fever or other symptoms of illness. There is also evidence that this type of vaccine may have potential as a treatment for those already infected.[5][6]

A single-dose blended vaccine capable of protection against several ebolavirus species could be deployed more efficiently, especially in a setting such as Western Africa. Such a blended VSV-GP vaccine expressing ZEBOV GP, SUDV GP, and MARV GP in equal concentrations was administered as a single dose to crab-eating macaques.[4] This blended vaccine provided 100% protection against a following infection with ZEBOV, SUDV, MARV, or even Taï Forest Ebola virus or TAFV.

Deployment of a vaccine can be even more efficient if it can be administered orally or intranasally as nose-drops. The efficacy of these modes of administration of a VSV?G-ZEBOV-GP vaccine were assessed, using ten crab-eating macaques.[7] Four animals received the vaccine orally, four intranasally, and two intramuscularly. Twenty-eight days later, all were infected with ZEBOV via intramuscular injection, already shown to be a more lethal mode of infection. None of the immunized animals developed any symptoms of clinical illness, while two additional control animals succumbed to the same infection.

Although filoviruses are not believed to be transmitted by aerosol in a natural setting, a bioterrorist might disperse an aerosol that could be inhaled. Hence the effectiveness of the corresponding vaccine was tested for protection of crab-eating macaques against aerosol challenge with both Ebola and Marburg viruses.[8] All vaccinated animals survived the exposure, while all control (untreated) animals perished.

A key requirement for such vaccines based on replication-competent (living) vectors or carriers is their safety, meaning their inability to cause the illnesses for which their unmodified ("wild") host or substrate is known. In this case, the original vesicular stomatitis virus carrier has the advantage of only rarely causing (flu-like) illness in humans, although it is a significant risk for farm animals. There have been reports of neurovirulence (causing disease within the nervous system) in rodents, macaques, cattle, sheep, and horses.[9] Hence both a rVSV-ZEBOV-GP and a rVSV-MARV-GP vaccine were each injected into the thalamus of seven healthy crab-eating macaques, while wild (unmodified) vesicular stomatitis virus was similarly injected into three animals.[9] Two of the latter three developed severe neurological symptoms, and major lesions were found in neural tissues from all three. On the other hand, none of the fourteen animals that received vaccine developed illness or neural lesions. These results were interpreted to strongly suggest that the original neurovirulence of the host virus is eliminated by the modification to make the vaccine, supporting efforts towards fielding such vaccines.

The "durability" of a vaccine is the time period after vaccination during which it retains its effectiveness. The durability of an rVSV-MARV-GP vaccine was tested in six crab-eating macaques.[10] Fourteen months after vaccination, the animals were exposed to Marburg virus. None showed any sign of clinical disease, demonstrating complete protection, while two control animals died. Such durability is typical of vaccines based on replication-competent vectors.[11]

The Public Health Agency of Canada holds the patent associated with the rVSV-filovirus-GP type of vaccine, but has licensed a small U.S. company called NewLink Genetics to develop rVSV-ZEBOV for use in humans, in its wholly owned subsidiary BioProtection Systems at the Iowa State University Research Park in Ames, Iowa.[12] In this work, BioProtection Systems is supported by the U.S. Defence Threat Reduction Agency, of the U.S. Defence Department.[13]

The Canadian government stated in 2014 that it would be distributing a quantity of rVSV-ZEBOV vaccine to West Africa in an attempt to help treatment of the Ebola virus epidemic in West Africa.[1][2]

On October 13, 2014 at the Walter Reed Army Institute of Research in Silver Spring, Md., NewLink Genetics began clinical trials of rVSV-ZEBOV on healthy human subjects to evaluate the immune response, identify any side effects and determine the appropriate dosage.[14][13][15]

As of October, 2014, the U.S. National Institute of Allergy and Infectious Diseases (NIAID) was recruiting healthy human volunteers for a "Phase 1 Randomized, Double-Blind, Placebo Controlled, Dose-Escalation Study to Evaluate the Safety and Immunogenicity of Prime-Boost VSV Ebola Vaccine in Healthy Adults".[16]

http://en.wikipedia.org/wiki/VSV-EBOV