MEMPHIS, Tenn., October 17, 1997-- In the first step of a multi-tier AIDS vaccinedevelopment program at St. Jude Children's Research Hospital, the Food and DrugAdministration (FDA) has approved a Phase I safety trial of a new AIDS vaccinedesigned to trigger immune responses to multiple, differing isolates of HIVusing the harmless outer coating of HIV known as the envelope.
Envelope vaccines have been shown in other laboratories to protect safelyprimates challenged with an immunodeficiency virus sharing the same HIVenvelope, as illustrated in August by research reported in the Proceedings ofthe National Academy of Sciences by scientists at Harvard Medical School. TheSt. Jude multi-envelope AIDS vaccine strategy is unique in combining 23different envelopes that represent many different isolates of HIV.
"Our ultimate aim is to discover the number and mix of HIV proteins, gatheredfrom HIV isolates found throughout the world, which will be effective inpreventing infection regardless of the isolate to which people are exposed,"says Julia Hurwitz, Ph.D., a co-developer of the St. Jude multi-envelope AIDSvaccine with Karen Slobod, M.D., respectively of the Departments of Immunologyand Infectious Diseases at St. Jude Children's Research Hospital.
The Phase I safety trial approved in September by the FDA will get underwayimmediately, beginning with the recruitment and evaluation of 9-18 eligible,healthy human volunteers, and is expected to last one to two years.
"At St. Jude Hospital we are very proud of the progress Drs. Slobod, Hurwitz andtheir colleagues have made in bringing the St. Jude multi-envelope AIDS vaccineto its first trial and they have our strongest possible support as they andtheir colleagues continue to pursue an AIDS vaccine," said Arthur W. Nienhuis,M.D., Director of St. Jude Children's Research Hospital.
Although every viral envelope consists of proteins called gp120 and gp41, eachenvelope looks different to the immune system because the proteins vary, muchlike human faces differ from each other. These differences have been an obstacleto vaccine development.
Scientists at St. Jude Children's Research Hospital have built upon theknowledge obtained by other vaccine research groups to select the buildingblocks -- or backbones -- for their HIV vaccine. One backbone is the smallpoxvaccine that globally eradicated smallpox in humans by the late 1970s. St. JudeChildren's Research Hospital is using 23 different HIV envelopes each containedin a smallpox vaccine backbone to constitute the first component of the St. Judemulti-envelope AIDS vaccine.
The St. Jude research team is also developing vaccine boosters as part of thevaccine program. Boosters include a DNA vaccine in which injected DNA promptsthe production by the body's cells of envelope proteins that then stimulate theimmune system. The DNA vaccine strategy was co-developed by Robert Webster,Ph.D., chair of the Department of Virology and Molecular Biology at St. JudeChildren's Research Hospital. Drs. Slobod and Hurwitz may also deliver abooster of purified envelope proteins.
The incorporation of many envelopes in the St. Jude multi-envelope AIDS vaccinestrategy is aimed at representing a cross section of virus envelopes that haveemerged in developing and developed regions of the world during the 15-yearglobal epidemic. Collecting the HIV envelopes, isolating the envelope sequencesand other related research efforts were initiated at St. Jude Children'sResearch Hospital four years ago.
"Although complete implementation of this vaccine strategy will take years, weare moving as quickly as possible without sacrificing attention to safety,quality and the St. Jude commitment to excellence," says Dr. Slobod.
While testing the safety of the St. Jude multi-envelope AIDS vaccine during theupcoming Phase I trial, the St. Jude research team will also measure volunteers'immune system response to the vaccine by evaluating their B cell (antibody) andT cell (cellular) immune responses. These data may be a preliminary indicationof volunteers' expected immune response to the vaccine during later trials. TheSt. Jude team constructed the vaccine in a manner that will permit determinationof whether immune system responses are the result of vaccination or actual HIVinfection unrelated to the vaccination.
Since the late 1980s, St. Jude Children's Research Hospital has also been activein developing treatments for children with AIDS. It is part of the AIDSClinical Trial Group, a national cooperative research network which allowspediatric AIDS researchers across the country to share resources andinformation.
St. Jude Children's Research Hospital, in Memphis, Tenn., was founded by thelate entertainer Danny Thomas. The hospital is an internationally recognizedbiomedical research center dedicated to finding cures for catastrophic diseasesof childhood. The hospital's work is primarily supported through funds raisedby the American Lebanese Syrian Associated Charities (ALSAC). All St. Judepatients are treated regardless of their ability to pay. ALSAC covers all costsof treatment beyond those reimbursed by third party insurers, and total costsfor families who have no insurance.
Materials provided by St. Jude Children's Research Hospital. Note: Content may be edited for style and length.
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