[메디컬리포트=Maricor Zapata 기자]
A new study shows that cow antibodies hold major hints to an effective HIV vaccine.The journey to an HIV cure has been a long and fruitless chase for decades.However, this is about to change as scientists are getting closer each day with new and exciting approaches that might end the demise of HIV infected people in the near future.
One of the medical tactics known to specialists involves the elicitation of broadly neutralizing antibodies (bnAbs) in people with good health.However, studies using this approach in both humans and animals, have in the past led to a dead end.
While cows cannot be infected with HIV, the new study shows that they can elicit powerful HIV-obstructive antibodies in a few weeks, as compared to humans where the process might take about 5-15 years if any.
Anthony Fauc, Director of the National Institute of Allergies and Infectious Diseases, says, “From the early days of the epidemic, we have recognized that HIV is very good at evading immunity.So exceptional immune systems that naturally produce broadly neutralizing antibodies to HIV are of great interest - whether they belong to humans or cattle."
The Big Question
Scientists are aware that people with chronic HIV infection generate bnAbs which are capable of overcoming the diverse nature of HIV.In 2009 IAVI, Theraclone and The Scripps Research Institute conveyed one type of bnAb that can reach hidden areas of the virus using its long arm-like loops.
With regard to this, prior studies by Vaughn Smider, from The Scripps Research Institute had a role in conveying that cow antibodies have similar long arm-like loops.These findings offered the possibility that the features of cattle antibodies would access vulnerable epitopes of the HIV, given that the virus contains sugar coating that protects its vulnerable areas from antibodies.
Based on the existing knowledge, a group of scientists from different research institutions teamed up to find out what would happen if cows were immunized with the HIV immunogen.Devin Sok, the lead author of the study and director of the International Aids Vaccine Initiative (IAVI), says that it is a remarkably simple and profound concept. “Since we know that some human bnAbs have longer-than-average loops, would immunizing animals with similar antibody structure result in the elicitation of bnAbs against HIV?" He adds.
HIV and Antibodies
HIV is known for its cunning nature, which it illustrates by displaying insignificant forms of this protein so that the immune system attacks the wrong protein.Scientists, therefore, developed an immunogen that mimics the protein target and got disheartening results.While the immunogen elicited good antibodies for the first form of the virus, it failed to elicit antibodies for the other different variations of the virus.However, findings from the new study offer clues that fill the gaps to some of these mishaps.
To determine what would happen, scientists first have to identify a single protein on the surface of HIV that would act as the bnAb target.They then develop an antibody that identifies different variants of the protein so that it offers protection against all possible forms of the HIV.
Sok notes that the study demonstrates the possibility of producing these antibodies in animals.More so, the exercise can be achieved hastily and reliably by the use of an easy and effective immunization strategy if administered in the right environments.
During the study, four cows were immunized with the BG505 SOSIP immunogen.The results were remarkable as they all elicited bnAbs to HIV in a period of 35 to 52 days.This was a huge leap since the same response takes humans HIV infected humans many years to develop.
The study shows that about 10 to 20 percent HIV infected humans develop bnAbs.More so, they only start generating these antibodies years after infection, a time when the virus has long mutated.
Findings from the study shed light on clues to further the search for an HIV vaccine.This is because researchers can now try to find methods that elongate the length of loops, thus guarantee a chance of eliciting bnAbs that would offer protection through vaccination.
Mark Feinberg, IAVI CEO says, "Scientific innovations like this are what propel the field forward," said IAVI CEO Mark Feinberg. "This surprising set of results warrants further exploration and has potential applications not only in HIV prevention and treatment but to the rapid development of antibodies and vaccines against other infectious diseases."
The ability of cattle to produce bnAbs against the HIV in weeks provides a significant breakthrough in the search for an effective vaccine.More so, it opens room for future research on vaccines for evolving pathogens.
The study was the first ever successful approach that used immunization to prompt the production of HIV fighting antibodies.