Inside-out cells offer target for antiviral drugs
By Julie Steenhuysen
CHICAGO (Reuters) - An experimental drug cured guinea pigs infected with a fatal hemorrhagic fever virus, raising hope for its use in a broad range of viral diseases including influenza, hepatitis C, HIV, Ebola and others, U.S. researchers said on Sunday.
“This is a whole new strategy for making antiviral drugs,” said Dr. Philip Thorpe, professor of pharmacology at the University of Texas Southwestern Medical Center at Dallas, whose research appears in the journal Nature Medicine.
Instead of attacking the virus directly, bavituximab, made by Peregrine Pharmaceuticals Inc, takes advantage of a defense mechanism used by the virus to hide from the immune system, Thorpe said.
When cells are under attack by a virus, this stress causes a fat molecule called phosphatidylserine, which normally lines the inside of the cell, to flip to the outside. “It’s like wearing your clothes inside out,” Thorpe, a scientific adviser to Peregrine, said in a telephone interview.
Bavituximab, a genetically engineered antibody, seeks out and attaches itself to these turncoat cells, flagging them for the immune system, which can then mount an attack,
“When injected into the bloodstream, bavituximab circulates in the body until it finds these inside-out lipids and then binds to them,” Thorpe said in a statement.
“In the case of virus infection, the binding raises a red flag to the body’s immune system, forcing the deployment of defensive white blood cells to attack the infected cells.”
Thorpe said conventional antiviral drugs try to exploit some property of the virus, but these drugs are often quickly defeated as the virus mutates.
By targeting an aspect of infected cells in the host, he thinks bavituximab is less likely to lose effectiveness, which commonly happens when a virus mutates.
In the study, Thorpe and his colleagues tested the compound on guinea pigs in an advanced stage of infection with a form of the Lassa fever virus, a disease that affects parts of West Africa.
Half of the animals treated with the drug alone were cured. When the researchers tested it in combination with the antiviral drug ribavirin, a drug that keeps a virus from replicating, 63 percent of the guinea pigs lived.
Thorpe said the findings suggest the drug might be effective on other types of hemorrhagic viruses, such as Ebola and Marburg. But this lipid flipping also occurs in cells infected with many other viral infections, including influenza, smallpox and rabies.
Peregrine is conducting early phase clinical trials of the drug in people with hepatitis C and human immunodeficiency virus, or HIV, which causes AIDS. And it has more advanced trials under way in cancer.
“We think it has tremendous potential,” Steven King, president and chief executive of Peregrine, said in a telephone interview. Peregrine funded the research along with the National Institutes of Health.
(Editing by Will Dunham and Todd Eastham)
--------------------------------------------------------------------------------------------Related Posts:
By Maggie Fox, Health and Science Editor WASHINGTON (Reuters) - Stem cells from tiny embryos can be used to restore lost hearing and vision in animals, researchers said Tuesday in what they believe is a first step toward helping people. One team repaired hearing in guinea pigs using human bone marrow stem cells, while another grew functioning
Full Post: Stem cells restore hearing, vision in animals
--------------------------------------------------------------------------------------------
By Gene Emery BOSTON (Reuters) - Sooner is better when it comes to treating infants born with the AIDS virus, HIV, researchers reported on Wednesday. A South African study of 377 babies found that giving newborns drug therapy right away, and not waiting until conventional tests showed a higher risk of becoming ill, cut the death rate
Full Post: Early treatment best for AIDS-infected babies
--------------------------------------------------------------------------------------------
By Andrew Quinn WASHINGTON (Reuters) - A global AIDS vaccine conference this week will seek fresh strategies against the HIV virus, with experts weighing the value of basic laboratory research against large-scale human clinical trials after a string of disappointments. Approaches focusing on “neutralizing antibodies” that would allow the human immune system to block infection completely, are
Full Post: AIDS vaccine focus shifts after disappointments
--------------------------------------------------------------------------------------------
By Will Dunham WASHINGTON (Reuters) - A quick urine test can spot a serious complication in people who have had a kidney transplant, enabling doctors to take steps aimed at preventing kidney failure, researchers said on Thursday. The test, described by researchers at the University of North Carolina, detects a viral condition called polyomavirus nephropathy that affects
Full Post: Urine test spots trouble after kidney transplant
--------------------------------------------------------------------------------------------
BERLIN (Reuters) - A bone marrow transplant using stem cells from a donor with natural genetic resistance to the AIDS virus has left an HIV patient free of infection for nearly two years, German researchers. The patient, an American living in Berlin, was infected with the human immunodeficiency virus that causes AIDS and also had leukemia.
Full Post: Bone marrow transplant suppresses AIDS in patient