Scientists have now unraveled the 3-D structure of a specific protein in feline immunodeficiency virus (FIV) that is also present in human immunodeficiency virus (HIV).
Study authors Akram Alian and Dr. Meytal Galilee — who are from the Technion – Israel Institute of Technology in Haifa — believe that their findings could open the door to new drugs that could tackle drug-resistant HIV-1.
The researchers recently reported their findings in the journal PLOS Pathogens.
HIV is a virus that attacks the body's T cells, which are immune cells that help us to stave off infection and disease. HIV-1 is the most common strain of HIV, accounting for around 95 percent of all cases.
It is estimated that around 1.1 million people in the United States are living with HIV. In 2016, there were more than 39,000 new cases of the virus diagnosed in the country.
When HIV first emerged in the 1980s, there was significant fear and stigma surrounding the virus; scientists knew very little about HIV, and there were no treatments for it.
But now, it's a different story; a person with HIV can live a long, healthy life thanks to antiretroviral drugs.
These medications work by reducing levels of HIV in the blood, to the point where the virus can be undetectable. This means that the virus does not impact a person's health and it cannot be passed on to other individuals.
However, not all people with HIV who receive antiretroviral drugs will achieve undetectable blood levels of the virus, and some individuals with HIV may develop resistance to these medications.
With this in mind, scientists are looking to develop new drugs for HIV, and Alian and Dr. Galilee believe that cats may help to meet this need.
HIV and FIV: What's the link?
FIV is similar to HIV; it attacks a cat's immune system, making it susceptible to infection. Although FIV and HIV belong to the same group of viruses, FIV cannot be transmitted to humans.
Still, because of the similarities between the two viruses, scientists have been studying FIV as a way to learn more about HIV.
For this latest study, Alian and Dr. Galilee focused on a protein called "reverse transcriptase." In FIV and HIV, this protein can "copy" the RNA genome of the virus into DNA. This DNA will then be "implanted" into the genome of the host, which causes their cells to replicate the virus.
In FIV, reverse transcriptase is resistant to reverse-transcriptase inhibitors (RTIs), antiretroviral drugs that can block this protein in people with HIV.
There is a concern that HIV could develop the same resistance to these drugs as FIV, but, should this happen, the new study findings may have already found an answer.
Findings may lead to new HIV treatments
Using purification and crystallization techniques, Alian and Dr. Galilee were able to decipher the 3-D structure of the FIV reverse transcriptase protein, which revealed the mechanisms behind the protein's resistance to RTIs.
The team found that reverse transcriptase protein within FIV generates a "closed pocket" that prevents RTIs from effectively binding to it, rendering it resistant to the drugs.
"We further show," say the authors, "that mutating the protein to facilitate binding of the inhibitors does not confer sensitivity to these inhibitors, suggesting that other variances inherent in FIV RT [reverse transcriptase] modulate a second layer of resistance."
They say that their findings may not only lead to new treatments for FIV, but they could pave the way for future HIV treatments, too. The researchers conclude:
"These insights can help in the development of novel drugs against evolving HIV-1 RT resistance."