Antibodies: A promising treatment for HIV?

21. April 2015
Share article

Previous attempts at antibody-based HIV treatments showed little success, possibly due to their inability to neutralize a broad range of HIV strains. Now, scientists show that use of 3BN117, a potent antibody with a much broader spectrum, can significantly reduce viral loads in infected people, for 28 days.

The human immonideficeincy virus (HIV) is the culprit responsible for causing AIDs, a sickness that changes the immune system making the human body susceptible to infection and disease. This virus, which can be found in bodily fluids such as semen and blood, is transmitted through blood-to blood contact or sexual intercourse. HIV can also be passed on to babies by their mothers, through breast-feeding.

Today, there are millions of people affected by this illness, worldwide. Currently treatment of HIV is achieved through a ‘cocktail’ of antiretroviral drugs, known as ARVs. These drugs are able to slow down the infection by attacking the virus at different stages of its life, allowing the patients to manage their symptoms and live a long and relatively comfortable life. However, ARVs are not a cure, and only act to control the amount of virus in a patient’s body, thus protecting the immune system. Even though we have come a long way with the treatment of HIV, the cure for this viral infection has managed to remain elusive, despite the significant research efforts of a great number of scientists around the world.

The idea of developing antibodies, and possibly a vaccine, for the treatment and prevention of HIV is not a new one. The human body has a difficult time fighting and neutralizing the virus on its own, because of the ability of this virus to mutate quickly, leaving the body unable to challenge the virus. However, there is a small percentage of HIV patients that can produce antibodies that neutralize a broad range of HIV strains, but only several years after the infection has occurred. Isolating these antibodies and using them as a form of ‘passive immunization’, against HIV infections, could prevent the virus from evolving. Previous work with passive immunization of animal models, such as mice and primates, was successful in reducing HIV virus loads in the body. However, initial trials in humans with several antibodies were not as promising, possibly due to their inability to neutralize a broad range of HIV strains.

The ‘broadly neutralizing’ antibody 3BN117

An exciting new study conducted in the laboratory of Michel Nussenzweig, has now managed to reignite interest in antibody treatment of HIV, through the promising results obtained with a new generation, broadly neutralizing antibody, 3BN117. 3BN117 is an antibody that binds potently to CD4, a glycoprotein found on the surface of T-cells that are responsible for organizing the body’s immune response to bacteria, fungi and viruses. HIV normally binds to CD4 on T-cells, allowing the virus to enter the cells, replicate and eventually destroy these T-cells – in the long run leading to reduced CD4+ T-cell counts, immunocompromization and increased susceptibility to infections. By binding to the CD4 site, 3BN117 prevents HIV from infecting T-cells and replicating.

For the study, the scientists tested four different doses of 3BN117 on a total of 29 participants. More specifically, each participant was administered a single dose of the antibody and monitored for 56 days, to check the viral load in their blood. From these participants, 17 had HIV and 15 of them did not take any antiretroviral medication throughout the study. When examining the blood titer levels of the virus in 8 participants that had received the highest dose of antibody – 30mg/kgr – the scientists observed a promising reduction in viral load by 8-250 times for a period of 28 days. In some participants, the amount of virus in their blood remained lower than starting levels, even at the end of the study period. However, in other participants, the effectiveness of the antibody seemed to drop to approximately 80% after 28 days of treatment, possibly because the virus had evolved to evade the antibody.

Is the 3BN117 antibody, the ‘cure’ to HIV we’ve all been hoping for?

Given the results obtained from this study, it seems that the new antibodies being developed for treatment of HIV are significantly more effective than ones used in previous trials, due to their ability to combat a broader range of viral strains. These results also raise hope for developing a vaccine against HIV, which can be used in uninfected individuals to prevent infection. However, for HIV treatment, since there is always the chance of viral resistance arising, it seems that antibodies cannot be used alone to treat HIV. Just like current HIV treatments, antibodies will need to be used in combination with other antibodies or drugs, in order to keep the virus in check. The goal, according to the lead of this recent study, Michel Nussenzweig, would be to administer a once-a-year shot for prevention and a combination approach for the cure. Which brings us to the other catch in HIV treatment – the high cost. Antibody treatments are very expensive, already beyond the ability of many of the patients suffering from HIV, since the greatest number of people suffering from this infliction come from countries with lower incomes. Adding extra antibody or drug treatments on top of the already significantly high costs, would make these treatments unreachable for the majority of patients suffering from HIV.

 

References:

Caskey, M, et al. Nature (2015)

Trkola, A, et al, Nature Medicine (2005)

Klein, F, et al, Nature (2012)

Barouch, D. H, et al, Nature (2013)

5 rating(s) (5 ø)
Uncategorized

Comments are exhausted yet.

Copyright © 2017 DocCheck Medical Services GmbH
Language:
Follow DocCheck: