Global & Disaster Medicine

Archive for the ‘FDA’ Category

FDA develops rapid and sensitive assay to assess antibody response to Ebola virus vaccine without using the virus

FDA

Scientists at the U.S. Food and Drug Administration (FDA) have developed an assay that assesses the ability of antibodies to neutralize Ebola virus, using a technique that does not require the use of Ebola virus itself and can be automated for rapid testing of large numbers of samples.

The new FDA assay is important because the effectiveness of most licensed viral vaccines is based on their ability to trigger production of neutralizing antibodies. Therefore, methods for assessing neutralization activity of antibodies will likely be an important component for evaluating the effectiveness of Ebola virus vaccines and identifying correlates of protection (measurable signs of immunity).

The assay is based on a widely used technique called micro-neutralization, which measures the ability of antibodies to prevent viruses from infecting animal cells and reproducing themselves. The greater the neutralization of a virus by antibodies, the fewer the number of viruses are able to infect cells and the less the viruses can replicate themselves by making copies of viral genetic material.

A key attribute of the assay is built upon the use of a genetically modified, non-disease-causing virus called vesicular stomatitis virus (VSV). The modified VSV carries part of the genome from Ebola virus and can substitute for Ebola virus in certain assays—an approach previously used at FDA.

The use of genetically engineered VSV eliminates the need for additional precautions, like a BSL-4 laboratory, because the modified virus is incapable of causing Ebola disease. These laboratories are designed for working with pathogens that pose a high risk of life-threatening disease through aerosol transmission and for which there is no vaccine or treatment. The FDA assay is appropriate for BSL-2 laboratories, which are widely available and do not require the more elaborate containment requirements of BSL-4. The need for BSL-4 laboratories for scientists to work with Ebola virus has complicated the worldwide effort to study the virus and develop and assess the effectiveness of Ebola virus vaccines.

The FDA scientists genetically modified different versions of VSV, so each one carried on its surface one of four variations of a molecule called an envelope glycoprotein (GP) found on different strains of the Ebola virus. Then they used a technique called quantitative polymerase chain reaction to measure the amount of genetic material produced by the hybrid VSV after it had been exposed to commercially available antibodies to Ebola virus. Automating the process should offer an important time advantage to public health scientists during investigations of an outbreak. The assay can determine within 6 to 16 hours if antibodies are effective against the Ebola virus.

The scientists showed that the assay was able to assess whether specific antibodies targeting each GP neutralized the different hybrid VSV variants, preventing the virus from infecting the cells and multiplying. Moreover, the results of the Ebola antibody assays agreed with those obtained by other, more complex assays, now used for such testing. This suggests that the assay will be useful in evaluating the ability of antibodies, triggered either by vaccines or natural infection, to neutralize specific varieties of the virus. Moreover, it might be possible to adapt the assay to assess neutralizing antibodies against other viral pathogens.

 

Title

Development of a micro-neutralization assay for ebolaviruses using a replication-competent vesicular stomatitis hybrid virus and a quantitative PCR readout

Vaccine 17 April 2017

DOI: 10.1016/j.vaccine.2017.03.019disclaimer icon

Authors

Stella S. Lee, Kathryn Phy, Keith Peden ⇑, Li Sheng-Fowler

Laboratory of DNA Viruses, Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, United States

⇑ Corresponding author at: Building 52/72, Room 1220, CBER, FDA, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States.
E-mail address: keith.peden@fda.hhs.gov (K. Peden).

 


FDA approves field trial on the release of Oxitec’s genetically engineered (GE) mosquitoes (OX513A) to suppress the local Aedes aegypti mosquito population

FDA

Update

August 5, 2016

The FDA has completed the environmental review for a proposed field trial to determine whether the release of Oxitec Ltd.’s genetically engineered (GE) mosquitoes (OX513A) will suppress the local Aedes aegypti mosquito population in the release area at Key Haven, Florida. After considering thousands of public comments, the FDA has published a final environmental assessment (EA) and finding of no significant impact (FONSI) that agrees with the EA’s conclusion that the proposed field trial will not have significant impacts on the environment.

FDA’s finalization of the EA and FONSI does not mean that Oxitec’s GE mosquitos are approved for commercial use. Oxitec is responsible for ensuring all other local, state, and federal requirements are met before conducting the proposed field trial, and, together with its local partner, the Florida Keys Mosquito Control District, to determine whether and when to begin the proposed field trial in Key Haven, Florida.


CDC’s Zika MAC test has been cleared by FDA (Emergency Use Authorization) for detecting evidence of the virus in human sera or CSF

**  the Zika MAC test is used to gauge recent infection and can detect the virus as early as 4 days after symptoms begin.

FDA approval letter

“….. the Food and Drug Administration (FDA) issue an Emergency Use Authorization (EUA) for emergency use of the Centers for Disease Control and Prevention’s (CDC) Zika Immunoglobulin M (IgM) Antibody Capture Enzyme-Linked Immunosorbent Assay (Zika MAC-ELISA) for the presumptive detection of Zika virusspecific IgM in human sera or cerebrospinal fluid (CSF)……”


FDA: A new indication for BioThrax (Anthrax Vaccine Adsorbed) to prevent disease following suspected or confirmed exposure to Bacillus anthracis for people 18 through 65 years of age in conjunction with recommended antibiotic treatment.

FDA

The U.S. Food and Drug Administration today approved a new indication for BioThrax (Anthrax Vaccine Adsorbed) to prevent disease following suspected or confirmed exposure to Bacillus anthracis, the bacterium that causes anthrax disease. The vaccine’s new use is approved for people 18 through 65 years of age in conjunction with recommended antibiotic treatment. BioThrax was initially approved by the FDA in 1970 for the prevention of anthrax disease in persons at high risk of exposure.

Anthrax disease, especially the inhalation form, is often fatal if not promptly treated. Anthrax is considered one of the more likely agents to be used in a biological attack, primarily because its spores are very stable and easy to disperse. Although it is rare, people may contract anthrax disease through natural exposures, such as contact with infected animals or contaminated animal products.

“With today’s approval of BioThrax, we now have a vaccine that can be used, together with antibiotic treatment, to prevent disease after exposure to anthrax spores,” said Karen Midthun, M.D., director of the FDA’s Center for Biologics Evaluation and Research.

BioThrax is the first vaccine to receive approval based on the Animal Rule. The Animal Rule allows animal efficacy data to be used as a basis for approval when human efficacy studies are not ethical or feasible.

Protective antibody levels, which were determined in rabbit and monkey studies, were used to predict efficacy in humans based on an assessment of the extent of antibody response achieved in human study participants. A 70 percent probability of survival in animal models from inhalational anthrax disease was deemed a reasonable level of protection and likely to provide reasonable benefit in humans.

The ability of BioThrax to increase the probability of survival after stopping post-exposure antibiotic treatment was assessed in rabbits. Rabbits treated with both antibiotics and BioThrax had a survival rate of 70 to 100 percent, depending on the vaccine dose administered. In contrast, in two studies of rabbits that received only antibiotic treatment, survival rates were 44 and 23 percent respectively.

The safety and antibody responses to BioThrax in humans were evaluated in a multi-center study conducted in the United States. Subcutaneous (under the skin) injections were given to 200 healthy adults in three doses at zero, two, and four weeks. The majority of study participants generated antibody responses that correlated to a 70 percent probability of survival that was observed in animal models.

The observed adverse reactions were comparable with those observed when BioThrax is used for pre-exposure disease prevention. The safety profile for BioThrax is well-established, with the majority of localized adverse events reported as tenderness, pain, swelling, and redness at the injection site, as well as limited movement of the injected arm. The most common systemic adverse reactions were muscle aches, headache, and fatigue.

BioThrax is manufactured by Emergent BioDefense Operations Lansing LLC, based in Lansing, Michigan.


Categories

Recent Posts

Archives

Admin