According to a report by the World Health Organisation in 2019, around 3.8 million people are currently infected with the Human Immunodeficiency Virus, commonly known as HIV, across the globe. At present, people with HIV are getting treated with a drug cocktail which is known as combination antiretroviral therapy (cART). This therapy has immensely improved the length and quality of life of HIV-infected individuals, but the treatment has many downsides which include the high cost of the treatment, the side effects it carries and the necessity to take the medications on a daily basis. Also, since HIV changes its structures (mutates) frequently, there have been cases of drug resistance.

In order to provide more robust therapies for HIV, scientists from the University of Utah Health have formed an injectable drug that they claim can block HIV from entering the body’s cells.

Cholesterol-PIE12-trimer: The D-peptide drug

According to the new study, published in the journal PNAS on 20th August 2020, researchers tested a unique drug called Cholesterol-PIE12-trimer (CPT31), which is a potent D-peptide. A peptide is a short chain of amino acids which are required for the formation of protein, whereas D-peptides are mirror images of naturally occurring peptides.

CPT31 restricts the entry of HIV by targeting gp41 N-peptide pocket region of the virus, which rarely mutates. Therefore, it does not get degraded in the body and lasts longer than natural peptides.

The new injectable drug study

To test the effectiveness of the drug, the scientists injected it into healthy macaque monkeys several days before they were exposed to a high dose of a hybrid simian-human form of HIV called SHIV. The results of the experiment were quite surprising as the monkeys showed no signs of infection and were completely protected from the virus. With this, the scientists concluded that CPT31 could be used as a prophylactic drug as it could prevent HIV infection during the initial exposure when there is a relatively small amount of virus in the body.

However, to find out its effectiveness in the body during the virus-multiplication stages, the researchers injected CPT31 to the monkeys who were not treated for SHIV infections and were exposed to high viral loads.

Result of the study

After 30 days of exposure, the scientists found that CPT31 significantly reduced the levels of SHIV in the bloodstreams. The scientists found that CPT31 not only prevented infection from a single high-dose rectal dose but significantly reduced the viral load by 2 logs in chronically infected animals.

When the scientists further tested the CPT31 drug in chronically infected monkeys who discontinued the use of the cART drug cocktail, they found that CPT31 solely prevented the rebound of the virus, which makes it a promising candidate for HIV prevention and treatment.

The scientists believe that CPT31 can be used as a long-acting injectable formulation against HIV which has to be administered once every three months.

Drawbacks of the drug

The scientists found that after two to three weeks, there was a rebound in the virus levels due to drug resistance, which is quite often seen while treating established infections with a single drug.

Moreover, scientists also found that though cART reduced the levels of SHIV to an undetectable level, the virus rapidly rebounded after discontinuation of the therapy.

For more information, read our article on HIV/AIDS.

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