How the Immune System Can Detect HIV
New HIV research has been revealing the workings of the human immune system. The hidden inner workings hold keys to solving some of the most formidable infections facing humankind. One such unlocked mystery is the discovery that one of the immune system’s sensor cells – cGAS – can detect HIV-1.
The cellular molecule, cGAS, is what sounds the alarm when there is an invasion of foreign matter. It has been believed, up until now, that cGAS could not detect retroviruses (such as HIV-1) because of the structural design of its DNA. Human DNA has two strands connected by molecular rungs. Retroviruses have just one strand. Researchers, therefore, concluded that this was one reason the body has trouble ridding itself of the intruder.
The HIV1 can, however, join together. They do this by twisting around each other to form a double strand. While these are more likely to be detected, the strand is often too short and passes through the cGAS radar. Here, however, is where the next piece in this chess game comes into play. The molecular building blocks of these DNA strands, called guanosines, can be detected by cGAS. It does not matter whether the HIV-1 is in its single-strand mode or not. Actually, it hardly mattered at all. What triggered the greatest immune response was the amount of guanosines. When more was added, the cellular defense response increased significantly. This strong reaction declined when the amount was lessened and all but stopped when it was removed altogether.
When HIV-1 infects a body, it imposes its DNA onto the healthy cell’s DNA. The result is a DNA that is curiously lacking in guanosines. It could be a reason as to why HIV-1 is particularly adept at cloaking – being virtually undetected by its host. However, some patients present with such a high number of HIV DNA that the guanosines that do remain still alert the cells, and the defense systems are activated. In these instances, the virus can remain suppressed indefinitely. This strong immune response is believed to be because of the detection of these all-important guanosines and the sensitive radar that detects it, cGAS.