Vaccines designed to fight HIV might not be accomplishing their tasks successfully because they are possibly making the targets of the virus which are the cells of the immune system more apt to get assaulted by the pathogen. Vaccines are meant to activate the CD4 cells of the immune system, and as a consequence, the virus might be feasting on the increased CD4.
Our human body is built such that it can fight against foreign invaders to keep its land pure from harmful agents. This is the general rule as to how we are protected from diseases. However, some pathogens do have the capacity of gaining grounds in our own body and consequently having our health deteriorating – this happens when our defense system (the immune system) cannot cope with the source of the disease.
HIV stands as one of those deadly invaders that the human immune system has failed to destroy completely. Furthermore, no effective vaccine has been formulated because the cunning virus has many a ‘war strategy’ at hand: it escapes the soldiers generated by the immune system. A new study has provided more insight as to how vaccines do not work against HIV, and instead, create more problems to the diseased.
Vaccines can backfire, beating the very purpose of their creation, and causing more infections. The scientists of the new study argued that the vaccines are, in fact, making the cells they are supposed to protect more ‘conspicuous’ to the virus. The vaccines are meant to activate the immune system to generate a response. However, the HIV affects the cells of the very immune system – this is where it gets tricky. The vaccines are instead making these cells larger and thus more prone to attack.
One of the cells of the immune system is the T cell, which sends signals to stimulate an immune response upon ‘meeting up’ with a virus, or other pathogen. Two types of T cells, the CD4 and the CD8, are involved in the immune response; the former, also known as helper T cells, identify the infection while the latter kill the immune system’s target. However, the virus itself is aiming for these very helper and killer cells. The CD4 are thus assaulted by the virus, which is then allowed to propagate itself by using the left-over machinery of the cells. Therefore, scientists have often opted for using CD4 as target.
The researchers assessed five different vaccines used on macaques against the monkey-equivalent of HIV, known as SIV. The monkeys were given a shot of either one of the five vaccines. They were later infected with SIV. Firstly, none of the vaccines proved to be successful at handling the infection.
The otherwise immunized monkeys were observed to have detectable levels of CD8 that, however, did not fight the infection. Moreover, at the start of the infections, the monkeys unexpectedly had a lower level of SIV in their system. Another observation that was made was that the monkeys had higher levels of CD4 in their rectal mucosal tissues prior to the infection itself. The vaccines have stimulated more CD4, thereby causing an increase in activated CD4, such that they are being unable to attack the virus, because they might have, instead, made the CD4 cells (which are the target of the virus) more apt to be attacked because of their high numbers.