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  • With its uncanny ability to disguise itself from the body's immune system, HIV is a

  • mysterious and powerful virus.

  • HIV is the most dynamic disease that we've ever seen.

  • So, how does HIV re-write your body's DNA? And how can a disease that was once a death

  • sentence now be managed with just one pill per day, with some patients living well into

  • their 90's?

  • Life expectancy has improved over years, and I'm very happy to be part of this journey.

  • My name is Sabin Nsanzimana. I work for Rwanda Medical Centre. I'm a medical doctor and an

  • epidemiologist. So I've been working for the Rwanda health sector for the past 14 years.

  • My role was head of HIV Care and Treatment Department.

  • HIV is a virus.

  • It belongs to the broader category of a retrovirus.

  • My name is Dr. Anthony Fauci and I'm the director

  • of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health.

  • I'm also an AIDS physician and scientist who runs a laboratory studying HIV/AIDS pathogenesis

  • Like Ebola and the coronavirus SARS-COV-2, HIV is a zoonosis, meaning it jumped to humans

  • from another species. In this case, it originated as Simian Immunodeficiency Virus in chimpanzees

  • and other non-human primates. So some decades and decades ago, the virus jumped

  • species from an animalwe don't know howpossibly because individuals in central

  • and southern Africa took non-human primates, butchered them, and ate them

  • and it is likely that during that process the virus got into the immune system

  • of a human and then continued to spread from human to human, predominantly by sexual contact.

  • But it's not just the infamous sexual transmission that spreads HIV. The virus can also be spread

  • via injection drug use, contaminated blood transfusions, or from mother to baby in utero,

  • or during childbirth or breastfeeding. Once it enters the body, HIV heads straight for

  • specific white blood cells within the immune system: T-lymphocytes, derived from the thymus,

  • which is an organ just beneath the chest. One type of T-lymphocyte has on its surface

  • a receptor, which is actually the CD4 molecule. When the virus comes in, the virus binds to

  • that receptor, fuses with and enters the CD4-positive T-cells that are the predominant conductor

  • of the orchestra of the immune system.

  • It's through those CD4 T-lymphocyte cells that HIV integrates itself into the body's

  • DNA. This is what retroviruses do best, but doctors are still stumped as to how exactly

  • HIV manages to sneak past the body's defenses.

  • We don't know how the virus, the HIV, actually convinces the cell to open up the window.

  • It's like you open up the window for your enemy. The virus, after it's changed itself,

  • will penetrate the nucleus of our cell. It will start to provide messages through our

  • RNA messenger to create new viruses. Like a factory, it starts reproducing itself,

  • spitting out virus, infecting other CD4-positive lymphocytes, killing them, diminishing their

  • function. You become very susceptible to a variety of infections that you otherwise would

  • not have to worry about. They're called opportunistic infections.

  • When CD-4 cells drop below a certain level, HIV progresses to its most dangerous phase,

  • AIDS. AIDS not only weakens the body's defenses against standard pathogens, like bacteria

  • and viruses, but also certain types of cancers like Kaposi's Sarcoma, which can cause tumors

  • in the lungs, liver, or digestive tract, or patchy, visible lesions on the legs and face.

  • In the 1980s, the AIDS epidemic shocked the world, and societal stigmatization, particularly

  • against at-risk groups like gay and bisexual men, ethnic minorities, sex workers, and the

  • homeless didn't speed the search for a cure. In fact, the first ray of hope came in the

  • form of a drug initially intended for a different purpose.

  • AZT, our first molecule, was meant for cancer treatment. And it worked, it stopped the virus'

  • progression. But the virus has many entry points: to the cell outer protection, to inside

  • the integration the virus, and after that also the virus will produce new viruses. All these

  • stages need treatment. The first treatments, unfortunately, were

  • too many drugs. So patients would tell you that they could take up to 20 pills a day.

  • Today, thankfully, it's a different story.

  • When HIV is caught soon enough, more options are available to patients.

  • It takes up to 72 hours to go deeper into the lymphocytes, so cells that would keep

  • it forever. At that stage we can stop the virus by providing treatment we call post-exposure

  • prophylaxis.

  • Pre- and post-exposure prophylaxis are known as PrEP and PEP, respectively.

  • When administered on a daily basis or within 72 hours of exposure, these methods can be up

  • to 99% effective for preventing HIV from taking hold. Once diagnosed, however, taking just

  • one pill per day can slow the virus' multiplication and allow the body's CD4 cell-count to catch

  • up. While it isn't a cure, this treatment, known as antiretroviral therapy, can bring

  • patients' viral loads down to below detectable levels, meaning they can't pass the virus

  • on sexually. Long-Acting treatment, injectables are coming

  • very soon. The same way we see for family planning, you take an implant for several

  • months or years. This is the near future. While the current cohort of HIV patients grows

  • older, new infections are down by 40% from the peak of the epidemic in the late 1990s.

  • But certain areas of the world, like Southern Africa, are still reeling from its effects.

  • Currently, throughout the world, there are 37 and a half million people living with HIV.

  • There are a little bit less than a million deaths per year.

  • Those fatalities are largely in places where the stigma of a diagnosis and the cost of

  • treatment present huge barriers to patients. And this makes developing an HIV vaccine a

  • sort of 'holy grail' for this global epidemic. Turns out that's proving to be as complex

  • and nuanced as HIV itself, as the virus can mutate over time. The way that it tricks the

  • immune system means that there really aren't any natural human antibodies to it that we

  • can use as a starting point, as we do with other vaccines.

  • Unlike almost any other infection that the body deals with, the body does not make a

  • very adequate immune response against natural infection with HIV.

  • In a clinical trial known as RV144, an investigational vaccine regimen

  • showed a modest level of efficacy, protecting 30% of patients from the virus' invasion.

  • Since it ended in 2009, scientists have worked to build on those results, testing candidates

  • all over the world. As we speak now, the candidates are being

  • tried in the United States, in Asia, in Africa. Here in Rwanda we have a vaccine trial site.

  • But still efforts are going on and we hope that one

  • day we may have a vaccine that can stop or can help people to get protected against HIV.

  • Now all that's left is to better implement the tools we do havelike improving the

  • cost and convenience of antiretroviral therapyand continue the search for the vaccine that will

  • put HIV to rest for good. It might not be in the next 525,600 minutes,

  • but we'll keep you posted.

With its uncanny ability to disguise itself from the body's immune system, HIV is a

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HIV患者の未来は明るいと思われるが、その理由はここにある (The Future Looks Bright for Patients with HIV, Here's Why)

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    林宜悉 に公開 2021 年 01 月 14 日
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