First Immature form of HIV seen at high resolution surprises researchers

The first structure of the immature form of HIV at a high enough resolution has been obtained by researchers, allowing them to pinpoint exactly where each building block sits in the virus. The study reveals that the building blocks of the immature form of HIV are arranged in a surprising way.

Sientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany and collaborators from Heidelberg University, in the joint Molecular Medicine Partnership Unit, have obtained the first structure of the immature form of HIV at a high enough resolution to pinpoint exactly where each building block sits in the virus. The study reveals that the building blocks of the immature form of HIV are arranged in a surprising way.

"The structure is definitely different from what we'd expected," says John Briggs from EMBL, who led the work. "We assumed that retroviruses like HIV and Mason-Pfizer Monkey Virus would have similar structures, because they use such similar building blocks, but it turns out that their immature forms are surprisingly different from each other. At this point, we don't really know why."

Briggs and colleagues used cryo-electron microscopy to study the protein lattice that surrounds the virus' genetic material. After infecting one of the cells in our immune system, HIV replicates, producing more copies of itself, each of which has to be assembled from a medley of viral and cellular components into an immature virus. This is the form that leaves the cell. The protein building blocks that make up the virus are then rearranged into the virus' mature form, which can infect other cells.

The first cryo-electron microscopy images of immature HIV, obtained at EMBL in the 1990s, surprised researchers by showing that the virus did not have a regular symmetrical structure, as had been assumed. That meant it was going to be difficult to get a detailed picture of the structure of its protein lattice. Two decades on, by optimising both how data is collected at the microscope and how it is analysed, Florian Schur, a PhD student in Briggs' lab, has now achieved an unprecedentedly detailed structure.

With this structure in hand, scientists have a basis to probe further. They can use it to decide where to focus efforts for achieving the even greater detail needed to explore potential drug targets, for instance. It will also enable researchers to understand how mutations might influence how the virus assembles. And the techniques themselves can be applied to a variety of questions.

"This approach offers so many possibilities," says Schur. "You can look at other viruses, of course, but also at complexes and proteins inside cells, with a whole new level of detail."

In future, the EMBL scientists will use the approach to look at other viruses and at the vesicles that transport material inside cells. They also aim to push the techniques even further, to allow them to see other parts of the viral proteins that are currently beyond their reach, but which they suspect play an important role in HIV maturation.

"In the long term, we'd also like to investigate how drugs which are known to inhibit virus assembly and maturation actually work," Briggs concludes.

Can social media help stop the spread of HIV?

In addition to providing other potential benefits to public health, all of those tweets and Facebook posts could help curb the spread of HIV. Although public health researchers have focused early applications of social media on reliably monitoring the spread of diseases such as the flu, a new article tells of a future in which social media might predict and even change biomedical outcomes.

Although public health researchers have focused early applications of social media on reliably monitoring the spread of diseases such as the flu, Sean Young of the Center for Digital Behavior at the University of California, Los Angeles.

"We know that mining social media will have huge potential benefits for many areas of medicine in the future, but we're still in the early stages of testing how powerful these technologies will be," Young said.

With the right tools in place, he says, social media offers a rich source of psychological and health-related data generated in an environment in which people are often willing to share freely.

His recent work on Behavioral Insights on Big Data (BIBD) for HIV offers the tantalizing possibility that insights gleaned from social media could be used to help governments, public health departments, hospitals, and caretakers monitor people's health behaviors "to know where, when, and how we might be able to prevent HIV transmission."

Young details a social-media-based intervention in which African American and Latino men who have sex with men shared a tremendous amount of personal information through social media, including when or whether they had 'come out,' as well as experiences of homelessness and stigmatization. What's more, they found that people who discussed HIV prevention topics on social media were more than twice as likely to later request an HIV test.
In the context of HIV prevention, tweets have also been shown to identify people who are currently or soon to engage in sexual- or drug-related risk behaviors. Those tweets can be mapped to particular locations and related to actual HIV trends.

What's needed now is the updated infrastructure and sophisticated toolkits to handle all of those data, Young said, noting that there are about 500 million communications sent every day on Twitter alone. He and a team of University of California computer scientists are working to meet that challenge now.
Although privacy concerns about such uses of social media shouldn't be ignored, Young says there is evidence that people have already begun to accept such uses of social media, even by corporations looking to boost profits.

"Since people are already getting used to the fact that corporations are doing this, we should at least support public health researchers in using these same methods to try and improve our health and well being," he said. "We're already seeing increased support from patients and public health departments."

Real-life social networking prompts people to get tested for HIV

Old-school face-to-face social networking is a more effective way to identify people with HIV than the traditional referral method, suggests research. The study shows that social networking strategies - enlisting people in high-risk groups to recruit their peers to get tested – is more efficient and targeted than traditional testing and referral programs, resulting in 2-and-a-half times more positive test results.

As many as 20 percent of HIV-positive people are unaware of being infected with the virus, and therefore do not receive vital treatment. In addition to missing out on medications that can improve their prognosis and quality of life, these patients also are more likely to spread the disease to others. Therefore, encouraging people at risk for HIV to get tested is critical.

SNS programs likely are more effective because they are more proactive than traditional counseling, testing and referral (CTR) programs, which are available to anyone who wishes to be tested but do not offer the same motivation as encouragement by peers.

"A limitation of the traditional approach is that many people who are at high risk of HIV never take the initiative to get tested on their own," said Ryan Westergaard, MD, PhD, MPH, lead author of the study and assistant professor of medicine at the University of Wisconsin School of Medicine and Public Health, Madison. "Our study found that using social network strategies, in which we enlist people at high risk to encourage peers in their social networks to get tested, results in a higher proportion of positive HIV tests - making our efforts more effective and allowing us to reach the people who need it most."

In the study, researchers collected data from 45 HIV testing sites in Wisconsin over four years. Through SNS, 54 of 2,169 (2.49 percent) people tested were HIV-positive vs. 440 of 48,318 (.91 percent) of those tested through CTR.

In SNS - which is growing in large cities - people at high risk for HIV are paid an incentive (typically $10 to $20) for every person they refer who gets tested. Some experts are concerned that these programs are costly, but the new research suggests that SNS is worthwhile, because it results in a higher percentage of positive tests.

"Some SNS programs limit the numbers of people a recruiter can refer for testing, based on the assumption that that they're just signing up everyone they know to make more money, even if they're unlikely to be HIV-positive," said Dr. Westergaard. "Our study showed that, on average, the 30th or 40th person referred for testing through SNS had just as high if not a higher probability of having a positive HIV test than the first five or 10 people referred.This suggests SNS can be a cost-effective tool to increase testing in specific high risk pools, such as men who have sex with men and transgender people."

Antiretroviral therapy benefits HIV-infected stimulant users

New clinical research from UC San Francisco shows that 341 HIV-infected men who reported using stimulants such as methamphetamine or cocaine derived life-saving benefits from being on antiretroviral therapy that were comparable to those of HIV-infected men who do not use stimulants.

That said, those who reported using stimulants at more than half of at least two study visits did have modestly increased chances of progressing to AIDS or dying after starting antiretroviral therapy compared to non-users. The data was collected between 1996 and 2012.

"Patients with HIV who use stimulants and other substances often experience difficulties with accessing antiretroviral therapy, partially due to the concerns of healthcare providers that they will not be able take their medications as directed. Findings from this study demonstrate that many stimulant users take their antiretroviral therapy at levels sufficient to avoid negative clinical outcomes. When we look at overall mortality, antiretroviral therapy leads to similar clinical benefits for both stimulant users and non-users, notwithstanding stimulant use," said the study's primary investigator, Adam W. Carrico, PhD., UCSF assistant professor of nursing.

The study included 1,313 HIV-infected men who have sex with men within the Multicenter AIDS Cohort Study, an ongoing nationwide prospective study of HIV infection among men who have sex with men in the U.S.

"If we are to achieve the goals of the President's National HIV/AIDS Strategy and UNAIDS to end the HIV/AIDS epidemic, we will need to treat HIV-positive active substance users for their HIV while encouraging them to stop or reduce their substance use. Programs integrating substance abuse services with HIV clinical care may both improve health outcomes for patients and reduce new infections," said Carrico.

The UCSF Division of HIV/AIDS at San Francisco General Hospital has created an integrated care delivery system that could serve as a model for other clinics, added Carrico. The HIV primary care clinic utilizes a patient centered team care approach that includes substance abuse services for stimulant and opioid users, along with mental health services, all located onsite. STOP, the "stimulant treatment outpatient program," within the clinic provides outpatient substance abuse and mental health treatment integrated with patients' primary medical care.

"The pattern of use varies and the real issue is whether patients can take their antiretrovirals as prescribed. We find that some patients are able to start taking antiretrovirals very reliably before they are able to decrease or stop their stimulant use, which often requires more complex behavioral, emotional, interpersonal and environmental changes. Being in an HIV primary care setting allows us to engage stimulant users even if they are not ready to go to specialty substance abuse programs or support groups," said Valerie Gruber, PhD, STOP director and UCSF professor of psychiatry.

Could there be an end in sight for AIDS?

South Africa is the epicentre of the HIV and AIDS epidemic with a staggering 6.4 million HIV infected citizens. In 1990 the WHO reported just 386 cases in South Africa. Over the next 15 years, despite warnings from scientists and policy makers, a tidal wave of infections ensued.  How can policy and health provision cope to improve the outlook?  A new article strategically examines the whole epidemic and identifies economic, epidemiological, and programmatic points for transition and future improvement.

Until 2001, HIV infection in the developing world amounted to certain death for all but the wealthiest. Development of Antiretroviral (ART) drugs now gives an infected young adult a life expectancy of 60. A massive break through, but each patient needs drugs for up to 30 years, representing a huge burden of cost and an enduring challenge for government and health providers to manage. The high cost of drugs may over reach the South African national health budget in a very few years. New infections outnumber AIDS deaths, increasing the number of people living with AIDS; patients requiring treatment increase faster than funding and the scenario escalates. Can the epidemic ever be managed out of an emergency into a more controlled state?

Prevention is central; only by reducing the rate of new infections can an eventual decline in HIV sufferers be achieved; an economic transition. After this tipping point those newly receiving treatment can outpace new infections; an epidemiological transition. In 2006 programmatic transition took place when newly initiated ART patients exceeded numbers of new patients needing ART. Sustained commitment to prevention and treatment has undoubtedly resulted in attrition of untreated HIV/AIDS patients. In future ART is proposed for a wider group of HIV patients, which the WHO believes will prevent 3 million deaths and 3.5 million new infections. It is clear though that despite this, AIDS and the financial load of ART will be here for many more generations, even if infection rates are brought under control.

The authors note "Although significant progress has been made in combating HIV and AIDS, the end of the epidemic may still be a long way off. However, sustained efforts to expand prevention and treatment programmes, as well as health systems strengthening and innovative financing, will ensure the long-term impact of these transitions."

Stem cell transplant does not cure SHIV/AIDS after irradiation of infected rhesus macaques

A new study reports a new primate model to test treatments that might cure HIV/AIDS and suggests answers to questions raised by the "Berlin patient," the only human thought to have been cured so far.

Being HIV-positive and having developed leukemia, the Berlin patient underwent irradiation followed by a bone-marrow transplant from a donor with a mutation that abolishes the function of the CCR5 gene. The gene codes for a protein that facilitates HIV entry into human cells, and the mutation - in homozygous carriers who, like the donor, have two defective copies - protects against HIV infection.

Several factors could have contributed to the cure of HIV/AIDS in the patient:

1. the ablation of blood and immune cells following irradiation killed all or many of the viral reservoir cells that are not eliminated by antiretroviral treatment (ART);
2. the CCR5 deletion mutation in the donor cells protected them and their progeny from HIV infection;
3. a "graft versus host" reaction occurred, where the transplanted cells and their progeny recognize the host cells as foreign and attacked and eliminated HIV-positive reservoir cells that survived the irradiation.

Guido Silvestri, from Emory University in Atlanta, USA, and colleagues investigated the relative contribution of the irradiation to eliminate the reservoir of HIV-infected cells. The scientists worked with the animal model of Simian Immunodeficiency Virus (SIV, a close relative of HIV that infects primates and causes a disease similar to AIDS) infection in rhesus macaques. Using a total of six monkeys (three of which served as controls and did not receive transplants) they performed, for the first time, hematopoietic stem cell transplantation in rhesus macaques infected with a chimeric simian/human immunodeficiency virus (SHIV) and treated with ART.

The researchers harvested hematopoetic stem cells from three macaques prior to infection (of all six animals) with SHIV. They also treated the macaques with ART to reduce viral load and mimic the situation in human HIV-infected patients on ART. They then exposed the three monkeys from which they had collected hematopietic stem cells to a high dose of radiation. This killed most of their existing blood and immune cells, including between 94 and 99% of their CD4-T cells -- the main target of HIV infection -- in the blood. The irradiation was followed by transplantation of each monkey's own virus-free hematopoietic stem cells. The latter can regenerate the blood and immune cells, and did so in all three monkeys within 3 to 6 weeks. Because the transplanted cells are not from a different donor, no graft versus host disease would be expected, and none was observed.

After that time, the scientists stopped ART in all six monkeys. As expected, the virus rebounded rapidly in the control animals. Of the three transplanted animals, two also showed a rapid rebound. The third monkey developed kidney failure two weeks after ART was stopped and was euthanized. It still had undetectable levels of virus in the blood at that time, but post-mortem analysis showed low levels of viral DNA in a number of tissues, arguing that none of the three transplanted monkeys was cured.

The researchers acknowledge a number of limitations of the study, including the small number of monkeys, and the relatively short period of ART prior to irradiation and transplantation. Nonetheless, they say their study "supports the hypothesis that myeloablative total body irradiation can cause a significant decrease in the viral reservoir in blood cells, even though it was not sufficient to eliminate all reservoirs." Their results, they say, suggest that in the cure of the Berlin patient, "the use of the CCR5 mutant donor and/or the presence of graft versus host disease played a significant role."

Having demonstrated in this first test-of-concept study that total body irradiation and hematopoietic stem cell transplantation in ART-treated SIV-infected rhesus macaques is feasible, the researchers express hope that "further studies using this model will provide critical information for the requirements to cure HIV infection in humans."

HIV antibody discovered that binds to novel target on virus

An NIH-led team of scientists has discovered a new vulnerability in the armor of HIV that a vaccine, other preventive regimen or treatment could exploit. The site straddles two proteins, gp41 and gp120, that jut out of the virus and augments other known places where broadly neutralizing antibodies (bNAbs) bind to HIV. This newly identified site on the viral spike is where a new antibody found by the scientists in an HIV-infected person binds to the virus. Called 35O22, the antibody prevents 62 percent of known HIV strains from infecting cells in the laboratory and is extremely potent, meaning even a relatively small amount of it can neutralize the virus.

Following their discoveries, the scientists found that 35O22-like antibodies were common in a group of HIV-infected people whose blood contained antibodies that potently neutralized a broad array of HIV strains. According to the researchers, this suggests that it might be easier for a vaccine to elicit 35O22 than some other known bNAbs, which are less common.

Since 35O22 binds only to forms of the viral spike that closely resemble those that naturally appear on HIV, the scientists believe a vaccine that elicits 35O22-like antibodies would need to mimic the natural shape of the spike as closely as possible. This would require a different approach than that used in many previous experimental HIV vaccines, which have included just parts of the viral spike rather than a structure that looks like the entire native viral spike.

In addition, the researchers report, the HIV strains that 35O22 neutralizes complement strains neutralized by other bNAbs. This suggests that eliciting or combining 35O22 with a few other bNAbs in a vaccine or a prevention or treatment regimen could likely neutralize the vast majority of HIV strains found around the globe, according to the scientists.

Tolerating, not fighting, viruses a viable survival strategy

In ecology, disease tolerance is defined as a host strategy not to fight a pathogen tooth and nail, but rather tolerate it to live (and survive) better in the long term. One key feature of tolerance is that the disease only progresses very slowly - if at all - even if the host carries a high pathogen load.

Roland Regoes, a senior scientist at ETH Zurich's Institute of Theoretical Biology, has now transferred this approach to HIV. He set about investigating whether there are infected people who are more tolerant of the HI virus than others and if so which factors this tolerance depends upon.

Regoes came up with the idea for the study during his postdoctoral stay in Atlanta, where he was working with researchers from a large primate centre. They studied sooty mangabeys (Cercocebus atys) infected with SIV, an HIV-like virus that affects primates. Although a large amount of the SI virus was found in their blood, some of the monkeys did not become ill. "The infection in this primate species is one of the best examples of disease tolerance," says the researcher. He and his co-authors -- all medical doctors -- are now interested in whether the concept of tolerance can also be carried over to human diseases. In order to determine which factors are linked to tolerance, the scientists evaluated the data from the Swiss HIV Cohort Study statistically.

Their analyses revealed that certain patient groups are more tolerant of HIV than others. For instance, the twenty-year-old group is more tolerant than sixty-year-olds, with the disease developing 1.7 times more rapidly in older patients than in their younger counterparts.

The same goes for the group of patients whose HLA-B genes come in two different variants. HLA-B genes are a group of genes which facilitate immunity to the HI virus. Every person has two copies of every gene, which do not have to be identical. If they are not, this is referred to as heterozygosity. If both HLA-B variants are identical, i.e. homozygotes, the tolerance of the virus is considerably lower.

Certain HLA-B variants are known to facilitate an immune defence against the virus geared towards its destruction. These variants are not responsible for tolerance. Instead, tolerance is linked to combinations of other HLA-B variants.

Regoes and his co-authors did not find any difference in tolerance between genders. The ETH-Zurich researcher recorded roughly the same high values in women and men, although on average women exhibit lower initial viral loads than men.

For his analyses, Regoes used the number of particular immune cells, the CD4+ cells, on the one hand and the viral load during the asymptomatic phase on the other. The latter is a key quantity in HIV infection. As soon as the virus infects someone, it multiplies rapidly and heavily before the immune system reduces its number to a certain level. From then on, the immune system keeps the pathogen relatively well under control for a long time. However, the number of CD4+ cells drops continuously until it reaches a critical level. If the number of these immune cells falls below 200 per millionth of a litre of blood, AIDS breaks out. The researchers calculated the tolerance of HIV sufferers to the virus from the correlation between the rate at which the CD4+ cells decreased and the viral load during the asymptomatic phase.

Tolerance and resistance are alternative but complementary defence strategies deployed by a host to combat pathogens. In the case of tolerance, it is not the destruction of the adversary and thus the reduction of the viral load that is the priority, but rather the alleviation of the negative effects of the infection for the host. This is not tantamount to capitulation. Instead, the strategy ensures that the evolutionary race between the parties cools off. "It is heading in the direction of commensalism," says Regoes -- a kind of ceasefire between two disparate partners. However, the two strategies have different evolutionary consequences: while tolerance tends to suppress the emergence of adaptations, resistance challenges the adaptability of viruses, which results in an evolutionary arms race with the adversaries.

"In the long run, one could try to use this ceasefire therapeutically," says the ETH-Zurich researcher. Tolerance-based therapeutic strategies could constitute interesting alternatives as they are not expected to lead to treatment-resistant pathogens.

Complexities of reducing HIV rates in Russia

Decreasing HIV transmission among Russian HIV-infected drinkers will require creative and innovative approaches, results of a new study conducted in St. Petersburg, Russia, show. While new HIV infections globally have declined, HIV rates remain high in Russia. This is due in large part to injection drug use and spread via heterosexual sex transmission.Results of a new study conducted in St. Petersburg, Russia, show that decreasing HIV transmission among Russian HIV-infected drinkers will require creative and innovative approaches.

While new HIV infections globally have declined, HIV rates remain high in Russia. This is due in large part to injection drug use and spread via heterosexual sex transmission. Alcohol use also has been shown to be related to risky sexual behaviors and sexually transmitted infections (STIs).

The study showed that a behavioral intervention did not lead to a reduction of STIs and HIV risk behaviors in Russian HIV-infected heavy drinkers when compared to the control group. This study was led by researchers from Boston University School of Medicine (BUSM), Boston Medical Center (BMC) and First St. Petersburg Pavlov State Medical University, Russia.

In this study, the researchers adapted a Centers for Disease Control and Prevention-best evidence risk reduction intervention for a Russian clinical setting and assessed its ability to reduce STIs and HIV risk behaviors among 700 HIV-infected heavy drinkers. The intervention stressed disclosure of HIV serostatus and condom use in two individual sessions and three small group sessions. Participants had a laboratory test at a 12-month follow up appointment to determine if they had contracted STIs. They also answered questions about risky behaviors, including unprotected sex, drinking alcohol or injecting drugs.

At the 12-month follow-up assessment, STIs occurred in 20 subjects (8 percent) in the intervention group and 28 subjects (12 percent) in the control group. Both groups, however, reported having decreased their participation in risky behaviors.

"Addressing prevention of HIV transmission from HIV-infected Russian drinkers, a group at particularly high risk for disease transmission, requires creative approaches and aggressive uptake of antiretroviral therapy," said Jeffrey Samet, MD, MA, MPH, professor of medicine at BUSM and chief of the section of general internal medicine at Boston Medical Center. "This study shows that we need to explore other options to help stem the growing epidemic.".

Why HIV patients develop dementia

HIV-associated neurocognitive disorders" (HAND) include disorders of the cognitive functions, motor capacities as well as behavioural changes. How exactly HAND occur has not, as yet, been fully understood. "Scientists assume that HIV is harmful to cells directly and that is also triggers indirect mechanisms that lead to nerve cell damage," explains Dr Simon Faissner (RUB clinic for neurology, St. Josef-Hospital).

The researchers strongly suspect that, once activated in the brain and the spinal cord, immune cells keep up a chronic inflammation level which then results in the destruction of nerve cells. An immune activation in peripheral tissue as well as therapeutic consequences may likewise contribute to nerve cell damage in the brain.

The HIV virus overcomes the blood-brain barrier hitchhiking on infected immune cells, the monocytes and probably the T cells. The researchers from Bochum tested the hypothesis that HIV-infected monocytes activate specific immune cells in the brain, the so-called microglial cells. These cells, in turn, respond by releasing harmful substances, such as reactive oxygen metabolites and inflammatory signalling molecules, i.e. cytokines. To test this hypothesis, the researchers developed a cell culture system in which they initially examined the effect of HIV-infected monocytes on microglial cells. The researchers simulated the individual steps of HIV infection and measured the volume of the cytokines released at each stage. Thus, they were able to demonstrate that releasing the viral RNA in the monocytes was a sufficient trigger for maximal microglial activation. Subsequent infection phases -- reverse transcription into DNA and the resulting formation of HIV proteins -- did not augment activation any further.

In the second step, they analysed nerve cells from rat brains to determine if the substances released by the microglial cells could lead to cell death. Compared with the control group, the number of cell deaths was indeed twice as high. Studies of liquor cerebrospinalis received from HIV-infected patients have shown a positive correlation with marker of neuronal degeneration in patients who did not as yet present any neurocognitive disorders. Detailed understanding necessary for therapeutic strategies

"Thanks to our research, we have gained a better understanding of the mechanisms of HIV-associated neurodegeneration," concludes Prof Dr Andrew Chan. "These results are likely to contribute to HAND biomarkers becoming established. In the long term, these data will be used to develop therapeutic strategies aiming at retarding HAND progression in HIV-infected patients." Starting points may include activation of microglial cells -- a method that is applied in other autoimmune diseases of the central nervous system, for example in multiple sclerosis.