The drug methamphetamine dramatically increases the ability of feline immunodeficiency virus, or FIV, to reproduce itself in a type of brain cell in cats, new research reveals.
If the finding holds true in humans, it could help explain why AIDS progresses more rapidly in drug abusers.
FIV is a close relative to HIV, the virus that causes AIDS. The research team, led by Michael Podell, professor veterinary clinical sciences and neurosciences at Ohio State University in Columbus, had been investigating cats as animal models for the neurological stages of HIV infection in humans. In late stages of the disease, infection of brain cells often causes dementia.
Cats and monkeys are the only animal models available for this stage of HIV infection because they are the only animals capable of carrying a virus similar to HIV that also causes a neurological infection.
The team set out to discover whether methamphetamine could boost the ability of FIV to infect particular brain cells called astrocytes. When they added FIV particles to a culture containing the cat cells, little infection took place. It was only when they added infected cat lymphocytes -- a type of blood cell -- that the viruses made it into the astrocytes.
That astrocytes were so resistant to infection came as a bit of a surprise. It suggests the viruses do not infect astrocytes directly, but instead are "handed off" from infected to lymphocytes to astrocytes.
"This is likely a way that the virus is transmitted to the brain," Lawrence Mathes, a professor in the college of veterinary medicine at the Ohio State University, and co-author of the study, told United Press International.
Addition of methamphetamine at levels similar to those found in a drug abuser's bloodstream caused the production of new viruses to jump by a factor of 10, the researchers reported.
"This might be an explanation for what clinicians have been feeling all along but couldn't prove," said Elyse J. Singer, associate professor of neurology at the University of California at Los Angeles. "Dementia might be ameliorated or treated by taking patients off methamphetamine drugs," Singer, who also is director of the National Neurological AIDS Bank in Los Angeles, told UPI. "In our treatment of patients, we need to emphasize how really bad these things are for the brain."
If confirmed with HIV and human cells, the findings could have implications for the treatment of HIV infection for drug abusers, and they could also shed light on the mechanisms behind HIV-related dementia -- a problem that could become more severe as therapies improve and HIV-infected individuals live longer.
The study "gives us insights as to what to look for in the animal (studies)," Mathes told UPI. "We have a mechanism that we can now test."
Preliminary analysis is underway of studies to see if methamphetamines cause progression of FIV infection in cats. Mathes would not elaborate on those results, but said the team has observed some "enhanced effects."
The study is scheduled to be published in the upcoming issue of the Journal of NeuroVirology.
