New virus could eradicate malaria, HIV, influenza

If you have ever seen Star Trek or if you’re a fan of science fiction, you may have heard of a retrovirus. Retroviruses are a class of viral vector vehicles that deliver genetic material into a host’s cell to provide instructions, often for the manufacturing of antibodies aimed at fighting infectious diseases. Unlike vaccination, which introduces foreign substances like antigens to illicit an immune response that triggers the production of antibodies, viral vectors provide cells with genetic instructions which the cell uses to manufacture the correct antibody.

While retroviruses are the darlings of science fiction writers and popularly used as plot devices, they are not the only class of viral vector. Their less flashy-sounding sister, the adeno-associated virus (AAV), has recently been making headlines as a potential vehicle treatment for diseases like HIV, influenza and malaria.

A recent study published by the Proceedings of the National Academy of Science of the United States of America (PNAS), has found encouraging results in laboratory tests using mice with AAV in what is known as vectored immunoprophylaxis (VIP) for the treatment of malaria. According to the study, “in areas where malaria transmission is unstable, VIP might be used to decrease malaria susceptibility to levels where the disease can be locally eliminated.”

Origins of this Third World virus killer

The idea behind VIP is to identify antibodies that broadly neutralize target diseases. In other words, the antibodies produced are effective at fighting a range of different strains of the same or multiple diseases. The genes encoding these antibodies are then incorporated with the AAV and injected into muscle tissue cells. The AAV becomes a factory within the cell, using cellular function to produce the antibodies.

The AAV is a particularly well-suited viral vector because it is comparatively harmless and persists in target cells for very long periods. Well-suited as it may be, effective AAV treatment is not without its challenges.

Unlike in mice and other mammalian hosts, AAV causes its own immune response in humans which can diminish the effectiveness of VIP treatment. The AAV-specific CD8 T-cell response in humans targets the virus for elimination, essentially destroying the antibody factory. The good news is that researchers have been working to combat this by using a hybrid of two variants of the virus, AAV2 and AAV8, to carry the genetic payload. While the solution is not perfect, it has shown promising results in avoiding the CD8 T-cell response. 

VIP treatment has also shown positive results in the treatment and prevention of HIV and influenza in earlier trials to complement its recent success at fighting Plasmodium falciparum (the malaria pathogen). The impact of VIP treatment cannot be overstated. Malaria alone “results in the death of between 500,000 and 800,000 children per year and thus presents a major infectious disease threat to public health,” according to a PNAS. If it works, it could be used to effectively eradicate some of the most pressing biological threats to humans. While human trials are still a ways off, and a commercial application even further, the results are very encouraging.