Saturday, September 30, 2023

Why Is There No Vaccine For Hiv

Myth: Joining An Hiv Vaccine Study Is Like Being A Guinea Pig

With rapid development of COVID-19 vaccine, why no vaccine yet for HIV?

Fact: Unlike guinea pigs, people can say yes or no about joining a study. All study volunteers must go through a process called informed consent that ensures they understand all of the risks and benefits of being in a study, and those volunteers are reminded that they may leave a study at any time without losing any of their rights or benefits. The HVTN takes great care in making sure people understand the study fully before they decide whether or not to join. All HVTN studies follows U.S. federal regulations on research, as well as international ethical standards and any country-specific requirements for the countries where our research is conducted. For more information, visit our Ethics page.

It’s Been More Than 40 Years Since The Virus Has Infected So Many People And Even Though It Is Now Possible To Control It People Are Still Questioning Why There Aren’t Any Vaccines Yet

The world has survived too many pandemics throughout history. Each one of them has hit humanity very hard and taken so many lives before we learned how to control them. Science has developed so many treatments against most of these like vaccines and prevention treatments but still, with all of that in mind, there is especially this one disease that exceeds our knowledge on how to prevent it.

Two ‘completely Different’ Viruses

Although HIV vaccine researchers have so far been unsuccessful, it’s not for lack of trying.

More than 400 HIV vaccine candidates have been tested in Phase I clinical trials, even if only five large-scale Phase III trials have been carried out each at a cost of more than $100 million.

The world may have firmly turned its attention and funds toward finding a vaccine for COVID-19 since the outbreak began in December 2019, but the difference in these timelines is not just about politics and money, Streeck said.

It also has to do with the unique composition of both viruses.

“SARS-CoV-2 and HIV cannot be compared in terms of structure and complexity,” Streeck told DW. The human immunosuppressive virus is “a completely different virus,” he said.

HIV continuously mutates making it extremely difficult for the human body and vaccine researchers to create the appropriate neutralizing antibodies to fight the virus

Unlike SARS-CoV-2, which is a very stable virus, the human immunosuppressive virus is extremely variable it’s constantly mutating. That makes it very difficult for HIV-infected peoples immune systems to make the right antibodies to fend off the virus, as it’s usually a step ahead of any response in the body. There are thousands upon thousands of HIV strains circulating in the global population. The HIV genome also integrates into the body’s DNA, effectively making itself invisible to the immune system.

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Why Are There Covid Vaccines But No Hiv Vaccines

Smallpox has been eradicated from the face of the Earth following a highly effective, worldwide vaccination campaign. Paralytic poliomyelitis is no longer a problem in the U.S. because of development and use of effective vaccines against the poliovirus. In current times, millions of lives have been saved because of rapid deployment of effective vaccines against COVID-19. And yet, it has been 37 years since HIV was discovered as the cause of AIDS, and there is no vaccine. Here I will describe the difficulties facing development of an effective vaccine against HIV/AIDS.

I am a professor of pathology at the University of Miami Miller School of Medicine. My laboratory is credited with the discovery of the monkey virus called SIV, or simian immunodeficiency virus. SIV is the close monkey relative of the virus that causes AIDS in humans HIV, or human immunodeficiency virus. My research has contributed importantly to the understanding of the mechanisms by which HIV causes disease and to vaccine development efforts.

Dr. Anthony Fauci discusses the difficulty of finding a vaccine for HIV/AIDS in 2017:

Why Wasn’t It Possible In The First Place

Why is it so hard to find a vaccine for HIV?

Up to this day, no one has managed to naturally recover from this infection. Usually, when you fight a virus like the flu or chickenpox and manage to recover from it, you naturally develop antibodies that will help you deal with future infections, but with HIV, that doesn’t work like that.

When a person gets infected, their immune system gets completely destroyed especially when it gets to be considered AIDS. Along with that, the virus keeps mutating inside the body so it is basically impossible that the person generates the needed antibodies to test them and try to create a vaccine out of them.

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So Why Is That So Hard To Do With Hiv

First of all, said Jefferys, lack of interest and funding are no longer really among the reasons. There was a period in the early 1990s when you could argue that HIV vaccine research was underfunded, he said. But by now, its a substantial budget. According to an analysis by the Resource Tracking for HIV Prevention Research & Development Working Group, a project of the HIV vaccine advocacy group AVAC, nearly $15.3 billion was spent on HIV vaccine research between 2000 and 2019. The money comes from philanthropic, public, and private groups like the Bill & Melinda Gates Foundation.

And if that money hasnt led yet to an effective vaccine, it has led to an enormous amount of information about both HIV and the immune system that led, in part, to the rapid development of COVID vaccines. HIV research helped reveal the importance of creating a vaccine using modified forms of invaders outer spike proteins to generate immune responses. HIV vaccine research also led to the perfection of mRNA as a vaccine method conceptused successfully for COVID, not so much for HIV.

Why the disparity? The short answer is that HIV is one of the wiliest, most slippery viruses known to modern science. And that answer breaks down into many factors.

Why Is It So Hard To Vaccinate Against Hiv

After researchers at the US National Institutes of Health and the Pasteur Institute confirmed that HIV infection led to AIDS in 1984, US Health and Human Services Secretary Margaret Heckler claimed that a vaccine would be available within two years. However, the very nature of HIV complicated things immensely.

Frontline AIDS lead for prevention Matteo Cassolato says: Unlike measles and other viruses, our immune system does not have the ability to naturally recover from HIV.

Since people who acquire HIV cant naturally clear the virus, we do not know what protection from HIV would look like in a person. If we knew that, vaccine researchers would know exactly what type of immune response the vaccine would need to elicit in our bodies to achieve protection from HIV infection.

Vaccines are designed to train the immune system to protect against an infection by using killed or weakened pathogens, or derivatives from them like antigens or DNA. These killed or weakened pathogens trigger an immune response, teaching the body to recognise an attack by the infection in question in the future.

But the human body doesnt produce the same kind of immune response to HIV as it does to pathogens that can be vaccinated against.

Cassolato says: When any foreign pathogen, enters the body, what normally happens is that the immune system detects the virus and tries to control or eliminate it. Special cells called CD4 and CD8 recognise the virus as something that doesnt belong and attack it.

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The Development Of Hiv Vaccines

HIV virions CDC Public Health Image Library

At a time when many infectious diseases were being brought or kept under control with global vaccination efforts in the 1990s, the human immunodeficiency virus , only identified in 1984, infected millions worldwide. From 1990 to 2014 the number of people living with HIV rose from 8 million to 36.9 million since the beginning of the HIV/Acquired Immune Deficiency Syndrome epidemic, AIDS has claimed more than 34 million lives.

HIV is a major public health concern not only because it cant yet be prevented by vaccination, but also because those it infects are infected for life with a virus that targets their immune system – making them more prone to other infections. The virus kills immune T helper cells called CD4+ cells, which are the coordinators of the human immune system. This is where the Acquired Immune Deficiency Syndrome name comes from: when HIV kills enough CD4+ cells, the infected persons immune system is unable to fight off infections it could ordinarily control. When the number of CD4+ cells drops below a certain point, a person is considered to have progressed from HIV infection to AIDS. People with AIDS are more susceptible to many types of infections, including those it could normally fight off, including types of pneumonia, tuberculosis, and shingles, as well as certain cancers.

This particular virus, however, poses unique challenges to vaccine development.

Myth: Western Scientists Are Unfairly Using People In Developing Countries To Test Hiv Vaccines

Why An HIV Vaccine

Fact: In order to find a vaccine that works in all kinds of people, it is necessary to test them in all kinds of people. This is especially true for groups of people that have been hardest hit by the HIV epidemic and who might benefit the most from a vaccine, such as those who live in sub-Saharan Africa. Protecting the well-being of study volunteers is the greatest responsibility in every study, and the HVTN works to make sure that studies follow the highest ethical standards and are done in collaboration with local scientists and researchers, and in consultation with local communities. Many studies are done in the US, Europe, and developing countries at the same time, and we follow the same procedures and international standards no matter where the study takes place.

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Mother To Baby Transmission

  • Mothers who want to prevent transmitting HIV to their babies should get tested as soon as possible. Early diagnosis and treatment can help prevent transmission to the baby more effectively.
  • If a mother has sexual partners who engage in high-risk behaviors, they should get tested again in their third trimester of pregnancy.
  • If a person is considering becoming pregnant and has a partner with HIV, they should consider taking PrEP. This may help protect them and their baby from contracting HIV while the mother is pregnant, during pregnancy, and while breastfeeding.
  • A person who has HIV should take ART as prescribed throughout their pregnancy and childbirth. A doctor may prescribe the baby ART for

Vax003 And Vax004 Efficacy Trials

1994 saw the emergence of two possible vaccine candidates that were used in efficacy trials. These vaccine concepts were advanced to efficacy trials because they conferred protection to chimpanzees following HIV challenge and were safe and immunogenic in phase 1/2 clinical trials in humans . The first two efficacy trials were carried out, from 1998 to 2003, by VaxGen in North America and Thailand . Based on the knowledge gained regarding genetic variability of HIV strains and the ability to use various co-receptors, the two initial candidate HIV vaccines were redesigned as bivalent gp120 vaccines for the North American trial and for the Thailand trial . The two redesigned gp120 vaccines were derived from R5 and X4 strains . The VAX004 efficacy trial recruited 5417 volunteers who were mainly men who have sex with men in North America, and the VAX003 trial recruited 2545 volunteers comprising intravenous injection drug users in Bangkok, Thailand. Unfortunately, in 2003, data analysis revealed that the two vaccines did not prevent HIV acquisition and did not ameliorate disease .

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More Than 100 Coronavirus Vaccines Are In The Works But Vaccines Remain Elusive For Many Diseases Weve Been Fighting For Decades

If scientists develop a SARS-CoV-2 vaccine within a year and a half, it would be a world record. The title is currently held by Maurice Hilleman, who turned his daughters throat swab into a licensed mumps prophylaxis within four years. Otherwise, preventive measures typically take a long time to develop: Measles, for example, was a nationally recognized disease in the U.S. for over 50 years before a vaccine was ready. In 1984, officials declared that an HIV vaccine would be ready for testing in two years. More than 35 years later, however, there is no HIV vaccine.

Why is it that some vaccines are harder to develop than others? Often, the answer has to do with the virus itself, and how it behaves in our bodies. Sometimes, a vaccine is not commercially viable. And in other instances, the perceived threat of an illness can prolong how long it takes to develop a way to stop it.

The Escape Mechanisms Of Hiv

Immunology and the Quest for an HIV Vaccine: A New ...

¿And why in one case the defenses know how to control the infection and in another not? The answer lies in the escape mechanisms of HIV.

This virus has a greater capacity to mutate, more than a thousand times higher than that of the coronavirus, and its envelope structure is different. The equivalent of the protein that SARS-CoV-2 uses to enter the cell , in HIV it is a folded structure the glycoprotein gp160 that only opens to enter the cell.

This is important because the neutralizing antibodies that block the virus recognize the protein that is like an open hand on the spike of SARS-CoV-2, but not the fist of HIV, remarks Alcamí, who details that another of the problems of AIDS virus is that its envelope is covered with sugars.

Sugars act as a shield and the antibodies produced by the immune system, even if they exist, fail to reach their target.

Whats more, HIV has the ability to hide, it can infect the cell but remain off, without multiplying, as on the bench. This is called the viral latency state, and cells that are in this state are reservoirs. Antiretrovirals prevent the virus from replicating but cannot attack its latent form.

Furthermore, in latency the virus is also capable of dividing the cell and each of the new cells carries the quenched virus in its DNA, which is a great obstacle to its cure and the development of vaccines.

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Four Decades Since Aids Epidemic Began But Still No Vaccine

Issued on: 01/12/2021 – 07:50

Covid vaccines began to show promise just months after the novel coronavirus started spreading across the globe. So why have decades of HIV/AIDS research yielded so little progress on a jab to prevent a disease that claimed some 680,000 lives in 2020?

As the globe marks World AIDS Day on Wednesday, why is there still no vaccine to protect people from the Human Immunodeficiency Virus ?

One answer is that the political will and colossal investment that have spurred on Covid vaccine development have largely been missing from AIDS vaccine research since HIV was discovered in 1983.

But another lies in the complexity of the science behind HIV.

With Covid vaccines, researchers worry about the vaccine being able to fend off a handful of variants that have become particularly worrisome, reads a June report by the International AIDS Vaccine Initiative .

But for HIV, there are millions and millions of different viruses that have resulted from the viruss stealth ability to rapidly mutate… It is this astonishing level of diversity that any HIV vaccine must contend with.

Olivier Schwartz, head of the viruses and immunity unit at the Pasteur Institute in Paris, says that while most people can recover naturally from an initial coronavirus infection and thus acquire immunity, this is not the case for HIV.

Only a handful of people naturally produce these antibodies when exposed to HIV.

An mRNA jab?

Lack of investment

So Where Are We Now And Is It Worth It

If an effective HIV vaccine is that hard to create, will we ever get there? Thats a really tough question, said Jefferys. In science, there can always be surprises, good and bad. Its possible that Janssens will have protective power.

Hes referring to a vaccine from Janssen, a Johnson & Johnson subsidiary, that has recently been in a phase 3 trial among cisgender men who have sex with men and transgender people in Latin America, Europe, and the U.S., alongside a phase 2b trial among cisgender women at high risk for HIV in several African countriesand that was due to be analyzing results in July. Its not an mRNA vaccine, but a so-called vector vaccine, which uses a modified version of a different virus to deliver important info to human cells on fighting off HIV. The vaccine isnt able to induce broadly neutralizing antibody responses, but rather creates other kinds of immune responses that researchers think may have a chance of preventing HIV infection.

If the Janssen results are negative, Feinberg cautioned, that may be the last attempt to create a vaccine that sparks these types of immune responses. Future trials, he said, would only have the B-cell wing of the immune system left to concentrate on. But, cautioned Feinberg, “broadly neutralizing antibodies have to go through multiple steps of evolution to get to the structure that can bind to HIV,” meaning that creating such a vaccine will itself be a slow, multi-step process.

Tim Murphy

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Progress In Developing An Hiv Vaccine

The first large HIV vaccine trial reported results in 2003. This trial tested a vaccine called AIDSVax which combined fragments of HIVs gp120 surface protein from HIV sub-type B. The vaccine was designed to produce neutralising antibodies against gp120. The trial found that the vaccine offered no protection compared to a dummy vaccine. A trial of a vaccine using the same design, but combining gp120 sequences from sub-types A and E, also showed no protective effect.56

A different vaccine strategy, using a vector virus to deliver HIV protein sequences to stimulate cellular immunity rather than antibody production, was tested in the STEP study. The trial vaccine used an adenovirus, a cause of common cold symptoms, as the vector. The STEP study was halted in 2007 after an analysis showed that the vaccine had not reduced the risk of infection.7

Subsequent analysis showed that people with the highest levels of pre-existing antibodies to adenoviruses had a higher risk of infection than people who received a dummy vaccine. The study results showed that more research was needed to develop vaccines to produce protective T-cell responses against HIV.

Current vaccine trials: Uhambo and Imbokodo

This vaccine, which has been developed by the pharmaceutical company, Janssen, is being tested on 2,600 women aged 18 to 35 in southern and eastern Africa. The results are expected by 2022.12

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