Five patent applications covering new, rapid diagnostic tests fortuberculosis are expected to be filed today by DynaGen Inc. ofCambridge, Mass.
TB, which is highly contagious, is characterized by a hackingcough and blood-stained phlegm. Existing TB diagnostic testsare slow or inaccurate, leading the American Lung Associationin New York to list TB diagnostic tools as a research priority.
"TB is a highly infectious disease and is best controlled byidentifying people who are TB-positive," said Shane McDermott,a program manager for the American Lung Association. TheWorld Health Organization estimates that more than 20 millioncases are reported annually worldwide, resulting in 3 milliondeaths.
A 1989 survey, the most recent, identified 23,495 cases of TBin the United States. For each TB patient identified, about 100tests are conducted, said Indu Muni, DynaGen's president. Theincidence of TB is rising at an epidemic rate among AIDSpatients, the homeless and prison inmates, according to theCenters for Disease Control in Atlanta.
One currently available test for TB requires only one hour, butsuffers from a reliability rate as low as 55 percent. Analternative test is accurate, but takes more than a month tocomplete. Meanwhile, an infected person is kept waiting fortherapy and may spread the disease to others. The disease canbe cured by antibiotics.
DynaGen's anticipated patent applications cover five testformats, all of which provide fast and reliable diagnosis of thedisease.
Two formats are saliva tests based on monoclonal antibodytechnology. One uses antibodies against the TB Mycobacteriatagged with a dye that fluoresces in the presence of thebacteria. A sophisticated fluorescence microscope is needed toread the results. The second test uses antibody-coated latexbeads that coagulate within five minutes in the presence of thebacteria. This test is designed for use in developing countrieswith less sophisticated clinical facilities.
The other three tests are based on the antigen produced by theTB bacteria. Antigens cause the body to produce antibodies towhich they then bind. DynaGen scientists have extracted andpurified the antigens and use their antibody-binding ability tomonitor antigen levels in the blood. Some patients -- the old,the young and people with advanced AIDS -- have difficultyproducing enough saliva. Blood tests are an essential part of thearsenal of rapid TB test kits.
DynaGen (NASDAQ:DYGN) expects in the next two months tocomplete an agreement with The Wellcome Foundation Ltd. ofLondon to continue the development of the TB tests. Under theproposed agreement, Wellcome would get exclusive worldwiderights to the TB tests.
Clinical trials of the TB diagnostic tests are expected to startthis summer at up to six sites worldwide, Muni said. The trials,an evaluation of results and an application to the Food andDrug Approval for marketing approval should be completed inthree months, he said.
-- Rachel Nowak BioWorld Staff
(c) 1997 American Health Consultants. All rights reserved.