Scientists at the International AIDS Vaccine
Initiative (IAVI) and The Scripps Research Institute (TSRI) have new data to
show that some human beings living with HIV generate powerful, HIV-blocking
at the International AIDS Vaccine Initiative (IAVI) and The Scripps
Research Institute (TSRI) show that some human beings living with HIV
generate powerful, HIV-blocking antibodies.
- This new type of broadly
neutralizing HIV antibodies (bnAbs) is most potent and can be used as a
template for vaccine design.
- An AIDS vaccine might be the only
hope of long-term treatment for people living with HIV.
research has been published in Immunity
and offers important insight
into a potential AIDS vaccine design.
"Uncovering the process by which
neutralizing antibodies develop is critical to HIV vaccine design," said
Elise Landais, Senior Research Scientist with IAVI and lead author of the
study. "A small fraction of people living with HIV can naturally
produce exceptionally powerful and broad antibodies that could prevent
HIV from infecting their immune cells
, but not until several
years post-infection - long after that protection can help them. But it is of
enormous interest to vaccine researchers."
Protocol C Epidemiological study
Protocol C is an
epidemiological study launched in 2006 by IAVI
and a wide range of
research partners study volunteers in sub-Saharan Africa and South Africa to
learn more about how HIV progresses and is transmitted. It comprises of more
than 600 volunteers to date who are in the early, acute stages of HIV
and undergoing antiretroviral
(ART- treatment that suppresses HIV replication); these candidates are
a high-value resource for vaccine design and development, as well as for cure
research. Samples from Protocol C volunteers have been collected and some of
them have been shared with researchers around the world.
‘The new findings of powerful neutralizing antibodies against various HIV strains could offer a possible template for vaccine design that would protect healthy people from HIV infection.’
One particular African individual (PC64)
infected with HIV subtype-A
was selected from the samples; the individual
had developed HIV broadly neutralizing antibodies (bnAbs) targeting the
vulnerable V2-apex site on HIV's surface.
This bnAb type is very potent and
has a breadth that can effectively neutralize almost all circulating HIV
A technique called next-generation sequencing
was applied to trace the development of bnAbs in reverse
. Pictures of the
interactions between PC64's immune response and the volunteer's infecting virus
were taken over time to retrace bnAb development back to the initiation stage.
During this retracing the particular viral changes that promoted the antibody
breadth were noted.
There were evolutionary similarities between the
virus in PC64 and another virus infecting a volunteer from another study called
CAPRISA who developed the same type of bnAbs.
Landais is hopeful that the new findings could
offer a possible template for vaccine design that would protect healthy people
from HIV infection
. Further research is necessary to achieve an optimal
Scientists at the IAVI Neutralizing
Antibody Center (NAC) at TSRI are using data from IAVI's partner
network of clinical research centers in Africa and India, to translate laboratory findings into a
workable vaccine and other long-acting HIV prevention
"Development of new and more effective
prevention is paramount to ending the HIV/AIDS epidemic
," said IAVI CEO
Mark Feinberg. "Of all the tools needed to curb new HIV infections, a vaccine is arguably the most
cost-effective and transformative
. We're unlikely to end AIDS without
Broadly neutralizing, HIV-specific monoclonal antibodies (bnAbs)
Broadly neutralizing, HIV-specific antibodies
(bnAbs) are neutralizing antibodies that can neutralize HIV viral strains.
They have recently emerged as a novel class of potential
therapeutic agents. They can target the HIV envelope (Env) and effectively suppress viral replication
New technological advancements over the last 5 years have led to the isolation
of new bnAbs with substantially increased potency and breadth.
The discovery of bnAbs has given us hope of a
discovery of a vaccine, not only limited to HIV, but also other rapidly
mutating viruses like influenza.
In 2013, most of the new HIV
infections (68 %) occurred in sub-Saharan Africa, with AIDS-related deaths
highest in countries like Nigeria (14 %), South Africa (13 %), India
(8 %), and the Russian Federation (2 %).
The AIDs-related death scenario is more predominant
in the above countries partially due to the
unavailability of antriretroviral therapy. Then again, ART is not a permanent
cure for HIV infection and is not sufficient to end the global AIDS epidemic.
What individuals living with HIV need is a
vaccine that is cost-effective and one that is a permanent cure for the
disease. References :
- Elise Landais et al. HIV Envelope Glycoform Heterogeneity and Localized Diversity Govern the Initiation and Maturation of a V2 Apex Broadly Neutralizing Antibody Lineage. Immunity, November (2017) DOI: 10.1016/j.immuni.2017.11.002
- Protocol C - (https://www.iavi.org/about-us/our-studies/60-about-us/observational-epidemiology/415-protocol-c)
- Stephenson KE, Barouch DH. Broadly Neutralizing Antibodies for HIV Eradication. Current HIV/AIDS Reports. 2016;13:31-37. doi:10.1007/s11904-016-0299-7.