Breaking News
May 26, 2018 - Scientists develop lab-based system to study mechanisms of common liver disease
May 25, 2018 - New guidelines may help pathologists to more accurately classify and diagnose invasive melanoma
May 25, 2018 - Immune cells promote lung cancer metastases by forming clots in tumors, study finds
May 25, 2018 - Can Excess Weight in Toddlers Cause Brain Drain?
May 25, 2018 - Studying insight
May 25, 2018 - Researchers reveal potent new mechanism of action for treatment of IBD
May 25, 2018 - Study shows lack of follow-up care for patients with concussion
May 25, 2018 - Study establishes the importance of haploid cells
May 25, 2018 - Coveted BMJ award bestowed on The Clatterbridge Cancer Center
May 25, 2018 - AACN outlines evidence-based protocols and clinical strategies to manage alarms
May 25, 2018 - Origami inspires researchers to develop new solution for tissue regeneration
May 25, 2018 - Melorheostosis – Genetics Home Reference
May 25, 2018 - Non-addictive pain medication changing therapy for substance use disorders
May 25, 2018 - Delayed lactate measurements in sepsis patients increase risk of in-hospital death
May 25, 2018 - Researchers identify novel epigenetic mutations as cause of neurodevelopmental, congenital disorders
May 25, 2018 - UD researchers examine connection between DNA replication in HPV and cancer
May 25, 2018 - Researchers identify neurons that play key role in aggressive behavior
May 25, 2018 - Researchers discover unexpected chemosensor pathway for predator odor-evoked innate fear behaviors
May 25, 2018 - Nearly one in three people know someone addicted to opioids
May 25, 2018 - Research suggests link between faulty gene, alcohol, and heart failure
May 25, 2018 - New findings could help fine-tune treatment for cancer patients
May 25, 2018 - New cancer treatment approach targets specific sugar receptors
May 25, 2018 - Skin responsible for uptake of cancer-causing compounds during barbecuing than lungs
May 25, 2018 - Early-onset cannabis use linked to further drug abuse problems
May 25, 2018 - Covered California takes aim at hospital C-section rates
May 25, 2018 - FDA Approves Palynziq (pegvaliase-pqpz) for the Treatment of Adults with Phenylketonuria
May 25, 2018 - Arthritis Glossary
May 25, 2018 - Study links breast cancer to the body’s internal clock
May 25, 2018 - Strenuous exercise in teenage years may protect against height loss later in life
May 25, 2018 - FDA approves novel enzyme therapy for adults with rare and serious genetic disease
May 25, 2018 - New research project aims at developing effective interventions for kids with DLD
May 25, 2018 - Middlemen who save $$ on medicines — but maybe not for you
May 25, 2018 - Study sheds new light on sharp rise in fatal drug overdoses in recent years
May 25, 2018 - Students propose revision of listeriosis guidelines for safer pregnancy
May 25, 2018 - TNFi Exposure In Utero Does Not Up Serious Infection Risk
May 25, 2018 - Organization of cells in the inner ear enables the sense and sensitivity of hearing
May 25, 2018 - Yoga May Be Right Move Against Urinary Incontinence
May 25, 2018 - Drinking recommended amount of milk could protect obese children against metabolic syndrome
May 25, 2018 - New cytokine network can repair tissue damage in the intestine, study finds
May 25, 2018 - Lyme disease researcher dispels misconceptions about ticks and provides prevention tips
May 25, 2018 - Penn researchers find link between social media usage and underage drinking
May 25, 2018 - Unique nanotechnology method to simplify skin disease diagnosis
May 25, 2018 - Study reveals new protective mechanism for tumor cells in breast cancer
May 25, 2018 - FRAME Alternatives Laboratory chosen for major European liver research collaboration
May 25, 2018 - Study shows yogurt may dampen chronic inflammation linked to multiple diseases
May 25, 2018 - Invasive cancers that are born to be bad show detectable differences from harmless tumors
May 25, 2018 - Study identifies new mechanism involved in development of Lou Gehrig’s disease
May 25, 2018 - UAB professor receives award for malaria prevention study in pregnant women in Cameroon
May 25, 2018 - Study provides blueprint of how fruit flies can be used to screen potentially pathogenic human genes
May 25, 2018 - New drug-delivering nanoparticle could offer better way to treat brain tumors
May 25, 2018 - Kessler Foundation scientists compare two tests for assessing learning in individuals with MS
May 25, 2018 - Stroke Symptoms and Diagnosis (Beyond the Basics)
May 25, 2018 - Protein goes against the family to prevent cancer
May 25, 2018 - Drugmakers blamed for blocking generics have milked prices and cost U.S. billions
May 25, 2018 - Speakers announced for National Medicines Symposium 2018
May 25, 2018 - GSK Receives FDA Approval of Arnuity Ellipta for Asthma in Children From 5 Years of Age
May 25, 2018 - Pfizer settles kickback case related to copay assistance for $24m
May 25, 2018 - Nuclear pore functions are essential for T cell survival
May 25, 2018 - Study defines molecular basis to explain connection between mother’s nutrition and infant growth
May 24, 2018 - IHI hosts representatives to develop a national action plan for patient safety
May 24, 2018 - Zika detection breakthrough by University of Queensland
May 24, 2018 - FDA Alert: 95% Ethyl Alcohol Product by Ethanol Extraction: Recall
May 24, 2018 - New method allows scientists to study how HIV persists
May 24, 2018 - Study reveals rate of vertebral and non-vertebral fractures in children with leukemia
May 24, 2018 - Whey protein supplementation and physical activity aid women in improving body composition
May 24, 2018 - Seniors’ air pollution exposure linked to hospitalization for ARDS
May 24, 2018 - Home-based telehealth therapy program effective for stroke rehabilitation, shows study
May 24, 2018 - Addressing Parents’ HPV Vaccine Hesitancy Ups Vaccination Rates
May 24, 2018 - Opioid addiction treatment drug helps suppress HIV in former prisoners
May 24, 2018 - FDA warns against using teething remedies for babies
May 24, 2018 - Healthy lifestyle counseling program linked to reduced risk of developing cancers
May 24, 2018 - CU research sheds light on liver disease caused by intravenous nutrition
May 24, 2018 - Skin cream containing rapamycin reduces TSC-related facial tumors
May 24, 2018 - Suicide rates twice as high among black children finds new study
May 24, 2018 - Researchers find new method to treat severe asthma
May 24, 2018 - Scientists report new strategy for fighting bacteria
May 24, 2018 - South Asians living in the United States more likely to die of heart disease and stroke
May 24, 2018 - Health Tip: Why Get a Biopsy
May 24, 2018 - Metabolic Syndrome Prevalence by Race/Ethnicity and Sex in the United States, National Health and Nutrition Examination Survey, 1988–2012
May 24, 2018 - Motivation to move may start with being mindful
Microbiome research offers new clues to increased HIV risk in women

Microbiome research offers new clues to increased HIV risk in women

image_pdfDownload PDFimage_print

Drawing from data collected for years by AIDS researchers in six African nations, scientists have pinpointed seven bacterial species whose presence in high concentrations may significantly increase the risk of HIV infection in women.

The findings add strength and precision to a growing body of evidence that the makeup of bacterial communities in the vagina — the vaginal microbiome — may increase or decrease HIV risk for women, depending on which bacteria are there. These clues are particularly important in sub-Saharan Africa, where women account for 56 percent of new HIV infections.

Dr. David Fredricks, a physician-scientist at Fred Hutchinson Cancer Research Center and senior author of the study, said the results could lead to a better understanding of how biological conditions may promote infection by the virus that causes AIDS, and perhaps offer targets for future prevention research. The Lancet Infectious Diseases released the paper online today.

Fredricks is a leading expert on the complex microbial communities that live in the vagina and the role they play in health and disease. He and his Hutch team wrote up the study with researchers in Kenya and with University of Washington colleagues led by physician and epidemiologist Dr. Scott McClelland, who is first author on the paper.

The bacterial equivalent of a bad poker hand

Of seven bacterial species linked to higher risk, the most conspicuous of them is Parvimonas Type 1, an otherwise common bug not considered particularly worrisome. But to use a poker game analogy, the researchers found that women carrying high concentrations of that bug had been dealt the equivalent of a bad hand. They had much higher odds — 4.6 to one — of acquiring HIV than those who did not.

The study also showed that the odds of HIV infection increased as concentrations of that bacterium increased. Biologists call this a “dose-dependent response” — the more bugs, the more risk of HIV infection. Three other bacterial species had a similar dose response.

“When we see dose-response effect, it increases our confidence that this is real,” Fredricks said.

He said studies of microbial communities often show associations between bacterial populations and health impact, but frequently they lack corroborating evidence to validate the findings. In this study, two complementary methods of evaluating the effects of vaginal bacteria were deliberately used.

“We validated this,” he said. “No matter how we sliced and diced it, we found the same result. That tells us this signal is likely to be true.”

Most studies of microbes that colonize different parts our body — inside and out — suggest that a greater variety of bacteria in those locations is healthier for the human who harbors them. The greater the diversity of bugs in a person’s microbial jungle, the better. But Fredricks’ earlier research turned up a surprising exception: the vagina.

His studies have shown that women whose vaginas are colonized by a wide variety of microbial species are more likely to suffer from bacterial vaginosis, or BV. It is a common condition associated with malodorous discharge and an increased risk of sexually transmitted infections. Several studies have shown that BV is linked to a 1.5-fold increased risk of HIV, and a recent South African study showed that women with “high diversity” bacterial communities had a fourfold increase in their odds of acquiring HIV.

The new study is the first ever to link higher HIV risk to the amount, or concentrations, of specific vaginal bacteria.

Understanding how BV affects HIV

Fred Hutch HIV researcher Dr. Julie Overbaugh, holder of the Endowed Chair for Graduate Education, is a co-author of the new study. Reached in Kenya, she wrote in an email that the latest work “begins to more clearly define which bacteria species associated with BV are linked to HIV risk,” which is important for understand how BV affects HIV.

“The study was incredibly challenging because, to study bacterial cofactors of HIV risk, the team needed to identify samples collected just prior to HIV acquisition,” she said. “These types of cohort studies take years.”

Gathering this detailed information required a remarkable collaboration involving five of the largest studies of HIV risk carried out in Africa. It involved intensive molecular testing of swab samples from 87 women who had acquired HIV infection and of 262 who did not, and sophisticated analysis comparing the vaginal microbial communities in each of those groups.

Fredricks and UW’s McClelland were able to obtain frozen samples of vaginal swabs taken, in some cases, as far back as 2004. The studies included the Mombasa cohort, which tracks HIV infection in female sex workers in Kenya — for which McClelland is site leader — and the UW-led Partners in Prevention study funded by the Bill & Melinda Gates Foundation. The various studies included women from Botswana, Kenya, South Africa, Tanzania, Uganda and Zambia.

The results were consistent throughout Africa, and among three distinctly different groups of women at high risk of HIV infection: pregnant women, sex workers and women who were initially HIV negative but had HIV-positive male partners. “What this means,” said Fredricks, is that these results are generalizable to many women, at least in sub-Saharan Africa.”

Publication of the results, said McClelland, comes 10 years after he and Fredricks first envisioned such a study. It took three tries to obtain funding for the research, and another seven years to gather the samples and the data, analyze it and come up with the results.

‘A great example of team science’

“This is a paper where the heavy lifting came in several different places, starting with the field researchers,” McClelland said. “It was a huge amount of work involving teams in a dozen different sites. It is a great example of team science, with a lot of people doing fantastic work to make this come together.”

The study also depended on extensive, time-consuming analysis to identify the most important vaginal bacteria involved. Key to the research was the use of a two-step process to analyze the samples. First, the team used a gene hunting method known as PCR to find out which types of bacteria were most commonly found among the women in the study. The results from these screens produced a list of 20 suspect bacteria but no information on the quantity of each species.

In the second stage of the study, the researchers used another version of the gene-probe technology, called “quantitative PCR,” which yielded the vaginal concentrations of each of the 20 species in every sample, and linked it to HIV risk. This was the most important and novel test, the one that implicated each of the seven bacterial species.

The seven species of rogue bacteria linked to the highest increases in risk of HIV infection are: Parvimonas species Types 1 and 2, Gemella asaccharolytica, Mycoplasma hominis, Leptotrichia/Sneathia, Eggerthella species Type 1 and vaginal Megasphaera.

The teams already are heavily engaged in additional studies to replicate the results and to gain further insight into what makes these seven species in particular affect HIV risk. There appears to be no common denominator among the seven bacteria. None are seen as dangerous pathogens — disease-causing bacteria such as staphylococcus or E. coli. But the researchers suspect these bugs, alone or in combination, may have a role in promoting inflammation, an immune response that can bring to the vagina the very kind of infection-fighting blood cells that HIV is most prone to infect. Further research is needed to prove that suspicion.

McClelland said that BV can be treated with antibiotics, but the treatments are only modestly effective, and the condition has a high recurrence rate. The new study suggests that some bacteria involved in BV are more important than others in raising HIV risk, and that treating those bacteria with antibiotics might be a more effective way to protect these women from the virus.

Source:

http://www.fredhutch.org/

Tagged with:

About author

Related Articles