Antibodies offer AIDS vaccine clue

Published in Featured Articles
Monday, 22 October 2012 07:53

 

A response to the HI-Virus in two HIV positive women, which enabled them to make potent antibodies that would kill most of the HIV types from around the world, has provided South African researchers with potential clues for the development of an AIDS vaccine.

 

The study published on Sunday in the journal, Nature Medicine, describes how a unique change in the outer covering of the virus found in two HIV infected South African women enabled them to make potent antibodies which are able to kill up to 88% of HIV types from around the world. The discovery, described as “groundbreaking” provides an important new approach that could be useful in making an AIDS vaccine, according to the researchers.

 

For the last five years, the Centre for the AIDS Programme of Research in SA (CAPRISA) consortium, involving scientists from the National Institute for Communicable Diseases (NICD) in Johannesburg, the University of KwaZulu-Natal, University of Cape Town and University of the Witwatersrand, has been studying how certain HIV-infected people develop very powerful antibody responses.

 

These antibodies are referred to as broadly “neutralising antibodies” because they kill a wide range of HIV types from different parts of the world.

 

The CAPRISA team initially discovered that two KwaZulu-Natal women, one of whom participated in the CAPRISA 004 tenofovir gel study, could make these rare antibodies.

 

Through long-term follow-up laboratory studies on these two women, the team led by NICD-based scientists discovered that a sugar (known as a glycan) on the surface protein coat of the virus at a specific position (referred to as position 332) forms a site of vulnerability in the virus and enables the body to mount a broadly neutralising antibody response.

 

NICD lead scientist Dr Penny Moore said: “Understanding this elaborate game of cat and mouse between HIV and the immune response of the infected person has provided valuable insights into how broadly neutralising antibodies arise”.

 

Professor Lynn Morris, Head of AIDS Research at the NICD explained, “We were surprised to find that the virus that caused infection in many cases did not have this antibody target on its outer covering. But over time, the virus was pressured by body’s immune reaction to cover itself with the sugar that formed a point of vulnerability, and so allowed the development of antibodies that hit that weak spot”.

 

CAPRISA Director Professor Salim Abdool Karim explained that broadly neutralising antibodies are considered to be the key to making an AIDS vaccine.

 

While their existence has been known for a while, highly potent forms of broadly neutralising antibodies against HIV were only identified about 3 years ago.

 

Until now, it was not known how the human body is able to make these antibodies.

 

This study has discovered one mechanism by which these antibodies may be made.

 

To make this discovery, the research team studied the target of some of these antibodies, a sugar that coats the surface protein of HIV, forming a site of vulnerability.

 

By tracing back the evolution of the virus that elicited these antibodies, the team showed that this particular weak point was absent from the virus that first infected these women.

 

However, under constant pressure from other less powerful antibodies that develop in all infected people, their HIV was forced to expose this vulnerability over time. This allowed the broadly neutralising antibodies to develop. Analysis of a large number of other viruses from throughout the world, performed in collaboration with scientists from the University of North Carolina and Harvard University, suggest that the vulnerability at position 332 may be present at the time of infection in about two thirds of subtype C viruses (the subtype most common in Africa).

 

Hence, if a vaccine is developed to target this glycan only, it may not be able to uniformly neutralise all subtype C viruses; as a result AIDS vaccines may need to attack multiple targets on the virus.

 

This research was funded by the South African government’s Department of Science and Technology, the US National Institutes for Health and the Bill & Melinda Gates.

 

 

This article is courtesy of Health-e News Service.

 

Civil rights groups and communities have expressed their concerned about the failure of the Department of Health to release the National Aids Vaccine Strategic Plan (NAVSP) for 2013-2017.

At a recent community roundtable on Aids Vaccine Research and Development held at OR Tambo International Airport, stakeholders and community members expressed their unhappiness about the embargo on the release of the NAVSP and vowed to do everything they can to have it released earlier.

 

The Department of Health requested the South African Aids Vaccine Initiative (SAAVI) to develop the NAVSP in 2012, combining the expertiese from researchers all over the world, and communities and Community Advisory Groups in South Africa. However, since its development the document has been embargoed for public scrutiny without reasons.

 

The round table was held to strengthen advocacy around the development of an Aids Vaccine in the country, however the meeting was dominated by a call for the release of NAVSP.

 

During the round table, various stakeholders, some whom were involved in the NAVSP development, indicated their dissatisfaction with the embargo on the document as they believe it contains clear objectives on community involvement in AIDS vaccine research that is happening in the country.

 

Researchers from various organisation, including the Perinatual HIV Research Unit, the Aurum Institute for Health Research and the Desmond Tutu HIV Foundation agreed that the embargo creates suspicion about their activities to reduce HIV infections through vaccines and ARVs prevention research.

 

"If we ask the government to release it and they deny, we'll have to force them through demonstrations," said one of the round table participants.

 

Before dispersing the group agreed to form an advocacy group to put pressure on the Department of Health to release the document. - OurHealth/Health-e News Service

 

Tshilidzi Tuwani is an OurHealth Citizen Journalist reporting from Soshanguve in the Tshwane health district in Gauteng.

 

KZN could prove HIV prevention science to world

Published in Featured Articles
Thursday, 13 March 2014 11:17

While KwaZulu-Natal remains hard hit by HIV, a new study by the humanitarian organisation Medicines Sans Frontiers (MSF) may mean the province is turning the tide against the virus.

 

Presented at recent annual scientific Conference on Retroviruses and Opportunistic Infections in the United States, the MSF study surveyed about 5,650 people in Mbongolwane and Eshowe. As part of the study, people were interviewed and agreed to be tested for HIV. Those that tested positive for HIV also had the level of HIV in their blood, or viral load, measured

 

The study found that about one quarter of all participants were HIV-positive – a figure about 40 percent higher than the national average, according to UNAIDS.

 

But this shockingly high figure is only half the story.

 

The study also found that about 80 percent of those surveyed had been tested for HIV in the past six months and almost an equal percentage of those living with HIV were already on antiretrovirals (ARVs).

 

Against moderate rates of new infections found in the communities, the area’s continued high HIV prevalence rates are a sign that ARVs are keeping people alive longer, according to Matthew Reid, who coordinates MSF’s Eshowe project.

 

“Prevalence is like measuring water inside a bucket,” he says. “If there is a hole in the bucket, or people are dying from (HIV), then your bucket doesn’t fill up quickly and prevalence rates are not going to rise dramatically.”

 

“If you plug the hole and keep people alive on ARVs – which obviously is a good thing – then the level of water in your bucket is going to increase, and prevalence will be higher.”

 

Treatment is prevention

In 2011, a study conducted in several countries including South Africa found that HIV-positive people who started treatment early and had nearly undetectable levels of the virus in their blood were about 96 percent less likely to pass the virus onto partners. Scientists theorise that earlier HIV treatment and high treatment rates could prevent new infections in communities.

 

MSF’s Eshowe project is looking to take that theory from mathematical models to the real world. To do that, the KZN Department of Health has allowed MSF to start HIV patients on ARVs sooner than national guidelines recommend.

 

About 90 percent of the long-time ARV patients surveyed by MSF in KwaZulu-Natal had levels of HIV in their blood that were undetectable, according to Reid.

 

“Getting on treatment has benefits for the individual, who…will avoid HIV-related diseases,” Reid tells Health-e. “There are also potential benefits of protection of the community because someone with an undetectable viral load is far less likely to transmit the HIV.”

 

“The fact that the KwaZulu-Natal authorities have accepted to partner with MSF to initiate treatment early is a very encouraging sign of their direction in the fight against HIV,” he added.

 

To test its theory that high HIV treatment coverage can bring down new infections in Eshowe, MSF plans to conduct another study in several years.

 

This article is courtesy of Health-e News Service.

Massive HIV vaccine trial possible in SA soon

Published in Featured Articles
Wednesday, 29 October 2014 11:42

In 2009, the Thai vaccine trial produced the world’s first promising results from an HIV vaccine trial after HIV infection rates were 31 percent lower in trial participants who got the vaccine than in those who received the placebo.The only HIV vaccine in the world that worked slightly in Thailand also seems to work on South Africans.

 

Despite being fatter than Thai people and exposed to a different strain of HIV, 100 South Africans responded in a similar way to a vaccine that protected about a third of Thai people against HIV.

 

“We were really excited to see the vaccine got exactly the same (immune) responses in South Africans as in Thailand,” said Medical Research Council President Dr Glenda Gray at the inaugural HIV Research for Prevention conference that opened yesterday.

 

The Thai vaccine, known as RV144, protected 31 percent of people who received it in a massive clinical trial in Thailand involving 16 400 people.

 

Once the Thai results were known in 2009, the global HIV research community decided that is was a priority to test the vaccine in a country with high HIV rate, Gray told Health-e News.

 

For the past two years, the immune responses of the 100 South Africans vaccinated in Soweto, Klerksdorp and Cape Town have been under the microscope.

 

“We had to be pragmatic, said Gray. “The vaccine had to work for fat people, women and people who drink alcohol because we South Africans drink a lot.”

 

Over half the women in the South African study were overweight or obese.

 

Satisfied that the South Africans reacted as hoped, researchers are now preparing for a bigger trial with a modified vaccine that contains the strain of HIV most common in southern Africa.

 

If successful, trial could grow quickly

This trial, involving 200 people, starts in January but could leapfrog into a massive R1-billion trial within a year if the people respond according to the Thai trial.

 

“We have already set our ‘go or no go’ criteria based on the Thai trial and if we meet these, we can go straight into a Phase 3 trial of 7000 people by the end of 2016,” said Gray.

 

The Thai trial combined two vaccines. The first aimed to prime people’s immune systems to recognise the types of HIV most common in Thailand (sub-types E and B) and the other, injected later, aimed to boost their immune systems to fight infection.

 

The “primer” vaccine now has to be modified to contain HIV sub-type C, which is most common in South Africa.

 

Discussions have already been held with the Medicines Control Council to license the vaccine by 2019 if the Phase 3 trial goes well, and also to vaccinate children along with the current HPV vaccine to prevent cervical cancer, said Gray, who added that even if the vaccine only gave 50 percent protection, government would probably still license it.

 

“Medical male circumicision offers up to 60 percent protection against HIV, and we are rolling it out,” said Gray.

 

Meanwhile, Science and Technology Minister Naledi Pandor opened the conference by appealing to African governments to invest in health research to “assume responsibility for finding solutions to our problems”.

 

Pandor welcomed the inaugural conference, which aims to unite all biomedical efforts to prevent HIV, from vaccines to microbicides and condoms.

 

“The challenge is to translate our new health knowledge into products that are effective, affordable and accessible,” added Pandor.

 

An edited version of this story was first published in the 29 October edition of the Pretoria News.

 

This article is courtesy of Health-e News Service.

Quest for a TB vaccine

Published in Featured Articles
Monday, 25 March 2013 08:55

CAPE TOWN - It is shameful that a disease which is preventable and curable and has been around for so many years continues to kill over a million people each year, the world’s foremost tuberculosis vaccine experts heard today.

 

Held for the first time in Africa, the world’s top TB scientists will for the next three days meet at the University of Cape Town under the banner of the TB Vaccines Third Global Forum in their quest to develop the only tool that could have a sustainable impact on the TB epidemic – a vaccine.

 

“Modern TB vaccinology is about 10 years old, so it is very new and I believe we are now at a watershed moment,” said Professor Willem Hanekom of the South African Tuberculosis Vaccine Initiative and one of the world’s foremost scientists in the field.

 

Speaking at the opening plenary, Dr Lucia Ditiu of the World Health Organisation’s Stop TB Partnership said it was naïve to think that the world could eliminate TB without a vaccine. “We need some great tools, a vaccine,” she said.

 

She lauded health minister Dr Aaron Motsoaledi as “an inspiration, the best promoter and a great visionary”.

 

South Africa is now the largest procurer of the Gene Xpert, a machine that is able to rapidly diagnose some forms of TB, including drug-resistant strains.

 

Health department Director General Precious Matsoso concurred “we have no option, but to find a vaccine”.

 

She revealed that at Sunday’s World TB Day events at Pollsmoor Prison they had screened 735 inmates for TB with 12% testing positive. Government has announced a renewed focus on TB in prisons, where in some overcrowded facilities TB infection is almost certain. Inmates will be screened for TB once they arrive and twice a year after that.

 

“If we don’t deal with TB in prisons and people’s homes we are sitting on a big

time bomb,” said Matsoso. – Health –e News Service

 

SA offers HIV vaccine research hope

Published in Featured Articles
Wednesday, 09 October 2013 14:17

Ntando YaloBARCELONA - South Africa is the only country in the world where a large AIDS vaccine trial is being planned, as the global scientific community struggles to find a way to eradicate HIV.

 

Announced at this week’s international AIDS Vaccine Conference in Barcelona, the South African trial will involve the only vaccine shown to have some effect on the virus when it was tested among 16,000 people in Thailand. Released in 2009, the Thai trial’s results showed that HIV infection rates were 31 percent lower in participants who had received the vaccine than those who had not.

 

“On the eve of some of the most important vaccine trials, I am proud of the critical role that the people of South Africa will play,” said Ntando Yalo from the Networking AIDS Community Of South Africa, speaking at conference opening.

 

But the trial’s researchers are cautious.

 

Glenda Gray is the South African trial’s lead researcher and executive director of the Perinatal HIV Research at the University of the Witwatersrand. She told conference delegates that trial would begin by testing the Thai vaccine on a small group of people to confirm the vaccine worked as well in South African populations as it did in Thai participants.

 

“It might not show the same efficacy as in Thailand,” Gray said. “For example, South African women are bigger, and have different (levels of) exposure to the virus.”

 

With a national HIV prevalence rate of about 17 percent, South Africans are likely to have had much more exposure to the HIV than people in Thailand, where just one percent of the population is HIV-positive. The modest protection offered by the Thai vaccine might be too weak for South Africa, Gray added.

 

If the vaccine is effective within this smaller group, researchers will modify it for use against the predominant strain of HIV found in South Africa. This modified vaccine would be tested on about 240 people and, if successful, move to a larger trial involving about 5,400 people.

 

Chasing a “Machiavellian” virus

 

But the virus, described as “Machiavellian” by scientist Dr Scott Hammer at the start of the conference, continues to evade almost all attempts to eradicate it.

 

Johnson & Johnson Head of Research Dr Jerry Sadoff said he had been involved in creating 11 vaccines, none of which had taken more than seven years to develop. HIV was the exception, he said.

 

“You can make a career out of the AIDS vaccine – I have been researching it for almost 30 years,” he joked.

 

Most vaccines train the body to recognise and kill viruses by injecting people with small, non-toxic “deactivated” parts of the virus.

 

The body learns to make antibodies to fight the deactivated virus, so that when it is faced with infection from the live, dangerous virus, it is able to recognise and fight it.

 

But HIV’s constant mutation once it is the body makes it a moving target that is hard to pin down.

 

About two percent of people infected with HIV are able to contain the virus so that they don’t get sick. Scientists have been studying these “elite controllers,” including sex workers in South Africa, for years but still don’t yet know how their immune systems manage to do this.

 

Unlocking how our immune systems can produce “broadly neutralising antibodies” to fight HIV is “one of the holy grails of vaccine design,” according to Hammer.

 

But as scientists struggle to unlock the secrets of our immune systems and HIV, AIDS Vaccine Conference organisers have decided to move away from narrow focus on vaccines.

 

About 13 years after the first AIDS Vaccine Conference was held, the Global HIV Vaccine Enterprise will open next year’s conference to a wider range of scientists working on HIV prevention methods, including antiretroviral (ARV)-based vaginal or rectal gels – or microbicides – as well as other forms of ARV-based prevention and medical male circumcision.

 

This much larger gathering of HIV prevention experts will convene in Cape Town next year.

 

Organisers also raised the issue of a therapeutic HIV vaccine for the first time. Unlike the vaccine being tested in South Africa, a therapeutic HIV vaccine would aim to treat HV infections, not prevent them. A small therapeutic HIV vaccine trial is currently underway in the United States. – Health-e News Service.

School-based HPV vaccination campaign wraps up

Published in Breaking News
Friday, 31 October 2014 12:40

350 000 grade 4 girls 9 years and older received the first injection of this two-dose vaccine in March and April this yearAs a school campaign to inoculate girls against one of the leading causes of cervical cancer wraps in the Northern Cape’s Siyancuma Local Municipality, one nurse says parents need to know more about the human papillomavirus (HPV).

 

As a school campaign to inoculate girls against one of the leading causes of cervical cancer wraps in the Northern Cape’s Siyancuma Local Municipality, one nurse says parents need to know more about the human papillomavirus (HPV).

 

This month, grade 4 girls lined up for their second vaccination against HPV that will protect them from developing cervical cancer later in life. About 350 000 grade 4 girls 9 years and older received the first injection of this two-dose vaccine in March and April this year, according to the National Department of Health.

 

The campaign recently concluded in Douglas, Northern Cape in the province’s Siyancuma Local Municipality. Sister Mitzi Prinz helped lead the Douglas leg of the campaign and says awareness – and community buy-in – could be improved.

 

“Not everyone in our municipality had been informed regarding this campaign and that’s why not all parents and guardians gave permission for girls to be vaccinated,” said Prinz, who added that the vaccination programme was carried out in about 14 schools.

A lack of awareness is despite door-to-door efforts by local community health care workers to inform guardians about the benefits of the jab for young girls.

 

“We still have a long way to go but we’ll get there,” said Prinz, who also encouraged women who are sexually active to go for regular Pap smears.

 

In the public health sector, HIV negative women only get three free Pap smears starting at the age of 30, while HIV positive women are allowed more screenings because they are at higher risk of developing cervical cancer.

 

This article is courtesy of Health-e News Service.

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