Virus Discovery Offers New Clue in Infectious Disease Mystery
National Cancer Institute researchers have discovered a new human virus, a finding that will accelerate research into the causes of many unexplained infectious diseases and tumors.
The virus was isolated from six cancer patients, including two who also were infected with the AIDS virus.
Although the new human B-lymphotropic virus is not related to the AIDS virus, intense efforts are already under way to learn if it plays a role in acquired immune deficiency syndrome and other human diseases, including a mysterious outbreak of chronic flu-like illnesses near Lake Tahoe in 1985.
The novel HBLV virus appears to be a member of the herpes family of viruses, according to Dr. Robert C. Gallo, the director of the research team.
“There is no herpes virus that hasn’t turned out to have some medically serious consequences,” Gallo said. “It would be surprising if (this virus) played no role in human disease.”
Herpes viruses are responsible for a variety of diseases ranging from skin ailments to mononucleosis, birth defects and tumors, but many infected individuals either have no symptoms or recover completely. The viruses reside in the body for life and may be periodically reactivated.
The researchers still do not know how the HBLV virus is transmitted or how many people may be infected with it. Nor have they proved that it causes any human diseases.
“There is a possibility that it may be involved in some (lymph gland tumors) associated with AIDS, but we don’t have evidence one way or the other,” Gallo said. Similarly, he said, tests in progress on specimens from the Lake Tahoe area are “too preliminary to be interpreted.”
The virus was first detected in the summer of 1985, as a spinoff of research on the development of tumors in AIDS patients. Gallo is a co-discover of the AIDS virus. Previously, he and his co-workers had isolated the AIDS virus as well as identifying another virus that can cause leukemia in adults.
The findings appear in the Oct. 31 issue of Science magazine.
The discovery was primarily the work of S. Zaki Salahuddin, who has worked in Gallo’s laboratory of tumor cell virology for 10 years.
Salahuddin and other scientists used a powerful electron microscope to examine large “bizarre-looking” white blood cells from several cancer patients, Gallo said. To their surprise, they found virus particles, which looked like other herpes viruses.
The scientists tried to grow the virus particles in other human and animal cells, but again found surprising results.
The particles would infect only fresh human B-cells, a type of white blood cell that plays a major role in fighting infections. This feature distinguished it from other herpes viruses, which infect more or different types of cells, as well as from the AIDS virus, which infects a different type of white blood cell, called the T-4 cell.
Gallo chose to call it human B-lymphotropic virus, or HBLV for short. B-lymphotropic means that the virus grows in the B form of white blood cells known as lymphocytes.
Before announcing their discovery, the researchers purified the HBLV virus and demonstrated that it contained unique proteins and DNA.
The six adult patients include five men and range in age from 17 to 66.
Since the Science paper was written, the virus has been isolated from the white blood cells of two more patients. The researchers have found no evidence of the HBLV virus in the 12 AIDS patients without lymph gland tumors they have checked.
The other human herpes viruses are the Epstein-Barr virus, which causes mononucleosis and a variety of lymph gland tumors; varicella-zoster virus, which causes chicken pox in children and shingles in adults; cytomegalovirus, which may cause flu-like illnesses and birth defects, and herpes simplex viruses, which can cause painful blisters on the face and in the genital area.
