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Back To Vidyya Campylobacter Vaccine Exhibits Significant Immune Responses In Phase II Clinical Trial:

Responses Correlate With Protection Against Disease

Antex Biologics Inc. has announced that a recently completed Phase II clinical trial of Campyvax, a vaccine to prevent Campylobacter infections, showed significant immune responses that correlate with protection against disease. Development of the vaccine is proceeding; the US Department of Defense will support clinical trials through Phase III.

Campyvax is an oral vaccine for the prevention of gastroenteritis, diarrhea, and Traveler's Diarrhea caused by Campylobacter jejuni, a common pathogenic bacteria. The objectives of this randomized, double-blind, placebo- controlled Phase II clinical trial were to compare the safety and immune response achieved following four doses of the vaccine with that achieved following a two-dose regimen during an earlier clinical trial.

Vaccinees achieved a ten-fold increase in mean fecal IgA antibodies compared to baseline, significantly higher than observed following the two-dose regimen. Over 85 percent of vaccine recipients were found to have antibody secreting white blood cells, higher than that found among those who received the two- dose regimen. And 85 percent of individuals who received four doses of the vaccine showed an increase in levels of interferon gamma, an indicator of cellular immunity; a 12-fold mean increase in interferon gamma was observed among vaccine recipients. These cellular immune responses were also higher than those seen among those who received the two-dose regimen, and comparable to the levels observed following infection with Campylobacter.

"The significant mucosal and cellular immune responses to Campyvax demonstrate that this vaccine holds considerable promise to protect against Campylobacter infection and disease," commented Stephen Keith, MD, MSPH, President, Antex Biologics Inc. "Working with the US Department of Defense, Antex is pioneering the development of vaccines to prevent diarrheal diseases. Campyvax is the only vaccine currently in clinical development to prevent Campylobacter infections."

The US Navy has conducted clinical studies of Campyvax, including Phase I studies and a Phase II human experimental Campylobacter infection model. Antex's vaccine consists of a novel proprietary inactivated whole-cell Campylobacter preparation. Campyvax is based on Antex's patented Nutriment Signal Transduction (NST) technology, and is the subject of three issued US patents. NST is an innovative and proprietary platform for the development of products to prevent and treat a range of bacterial infections.

"The enhanced immune response observed following the four-dose regimen of Campyvax is particularly promising given the Campylobacter-specific fecal IgA and interferon gamma responses. These two measures of immunity have correlated with protection in previous clinical trials," remarked David Tribble, MD, MPH, Principal Investigator, Enteric Diseases Department, Naval Medical Research Center. "We are pleased with these results and look forward to continuing to work with Antex on the development of Campyvax."

Diarrheal diseases remain a major cause of death in the world. In the United States, diarrhea is one of the most frequent reasons given for visits to the pediatrician's office. Campylobacter is the number one food-borne pathogen in the US, with over 2.5 million cases of Campylobacter diarrhea in the US annually. Outbreaks and sporadic cases of Campylobacter gastroenteritis and diarrhea occur frequently among military personnel stationed in the US and overseas.

Worldwide, 400-500 million cases of Campylobacter diarrhea occur each year. Campylobacter infection is also considered to cause one of the most severe forms of Traveler's Diarrhea among visitors to less developed countries. Of great significance, Campylobacter can also cause reactive arthritis and Guillain Barre Syndrome, which can result in paralysis and death.

The increasing resistance of Campylobacter to antibiotics is becoming a national concern, and may increase the desirability of a safe, effective oral vaccine. Vaccination offers one of the best and most practical options for disease prevention and control among children, US military forces, and individuals traveling abroad.

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Editor: Susan K. Boyer, RN
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