This blog originated as a press release from ISGlobal, the Barcelona Institute for Global Health. Thanks to ISGlobal for permission to post it here.
A new study shows that extracellular vesicles from the malaria parasite Plasmodium vivax promote parasite adhesion to spleen cells
Extracellular vesicles (EVs) play a role in the pathogenesis of malaria vivax, according to a study led by researchers from the Barcelona Institute for Global Health (ISGlobal), an institution supported by the ”la Caixa” Foundation, and the Germans Trias i Pujol Research Institute (IGTP). The findings, published in Nature Communications, indicate that EVs from P. vivax patients communicate with spleen fibroblasts promoting the adhesion of parasite-infected red blood cells. These data provide important insights into the pathology of vivax malaria. The study was carried out at the Can Ruti Campus, with the participation of the IGTP Genomics platform, the Nephrology service of the Germans Trias i Pujos Hospital, and researchers from the Irsicaixa AIDS Research Institute.
Plasmodium vivax is the most widely distributed human malaria parasite, mostly outside sub-Saharan Africa, and responsible for millions of clinical cases yearly, including severe disease and death. The mechanisms by which P. vivax causes disease are not well understood. Recent evidence suggests that, similar to what has been observed with the more lethal P. falciparum, red blood cells infected by the parasite may accumulate in internal organs and that this could contribute to the pathology of the disease. In fact, the team led by Hernando A. del Portillo and Carmen Fernández-Becerra, recently showed that P. vivax-infected red blood cells adhere to human spleen fibroblasts thanks to the surface expression of certain parasite proteins, and that this expression is induced by the spleen itself. “These findings indicate that the spleen plays a dual role in malaria vivax,” says ICREA researcher Hernando A del Portillo. “On one hand, it eliminates infected red blood cells. On the other hand, it may serve as a “hiding” place for the parasite.” This could explain why P. vivax can cause severe disease in spite of low peripheral blood parasitemia.
|Hernando A. del Portillo and Carmen Fernández-Becerra|
To understand the molecular mechanisms responsible for this adhesion process, the research team turned its attention to something they have been working on for the last few years: extracellular vesicles. These small particles surrounded by a membrane are naturally released from almost any cell and play a role in communication between cells. There is increasing evidence that they could be involved in a wide range of pathologies, including parasitic diseases such as malaria. “Our new findings reveal, for what we believe is the first time, a physiological role of EVs in malaria,” says del Portillo, last author of the study.
The research team isolated EVs from the blood of patients with acute P. vivax infection or from healthy volunteers and showed a very efficient uptake of the former by human spleen fibroblasts. Furthermore, this uptake induced the expression of a molecule (ICAM-1) on the surface of the fibroblast which in turn serves as an “anchor” for the adherence of P. vivax-infected red blood cells.
“Our study provides insight into the role of extracellular vesicles in malaria vivax and supports the existence of parasite populations adhering to particular cells of the spleen, where they can multiply while not circulating in the blood” says Fernández-Becerra, senior co-author of the study. “Importantly, these hidden infections could represent an additional challenge to disease diagnosis and elimination efforts as they might be the source of asymptomatic infections,” she adds.
Toda H, Diaz-Varela M, Segui-Barber J. Plasma-derived extracellular vesicles from Plasmodium vivax patients signal spleen fibroblasts via NF-kB facilitating parasite cytoadherence. Nat Commun 11:2761. doi: 10.1038/s41467-020-16337-y PMID: 32487994.
With a focus on screening local healthcare workers and first responders, the epidemiological study seeks to understand the prevalence of coronavirus infections in the community. The lab of ERCC2’s Louise Laurent is part of the core research team.
LA JOLLA, CA—A consortium that includes many of San Diego’s top medical and scientific research institutes has launched a large-scale COVID-19 screening effort to better understand the spread and prevalence of the virus in the local community, with an initial focus on evaluating healthcare workers and first responders.
Known as the San Diego Epidemiology and Research for COVID Health (SEARCH) alliance, the cross-institutional collaboration is co-led by scientists and clinical researchers at Rady Children’s Hospital-San Diego, Rady Children’s Institute for Genomic Medicine, Scripps Research, and University of California San Diego.
| As part of the SEARCH study, San Diego fire fighters are screened for SARS-CoV-2, the virus that causes COVID-19. .|
Credit: Don Boomer
The research project is applying innovative technologies and screening strategies to paint a more comprehensive picture of how widely COVID-19 has spread—and continues to spread—throughout the San Diego area. All data collected will contribute to an epidemiological study that will encompass active cases of COVID-19 as well as its “silent spread” to people who never developed symptoms.
“For health officials to gain the upper hand on a virus in our community, they need more complete information about how it’s moving through the population,” says Lauge Farnaes, MD, PhD, assistant medical director at Rady Children’s Institute for Genomic Medicine. “Our goal is to fill those gaps of knowledge by leveraging San Diego’s unique expertise in science and medicine.”
As COVID-19 cases in San Diego began to rapidly increase in late March, the collaborators sprang into action. Through emails and Zoom meetings, they formulated a research proposal and created a scalable testing framework that would enable them to screen symptomatic individuals as well as people who may have COVID-19 without showing symptoms.
In the initial phase of the program, nasopharyngeal swabs are used to collect samples from study participants at a local drive-up site and the samples are screened at research laboratories at Scripps Research and UC San Diego. Any positive results are then confirmed by Rady Children’s Institute of Genomic Medicine’s nationally accredited and certified clinical laboratory.
In addition, the researchers are conducting “serosurvey” studies that look for antibodies to the virus. Serosurveys, short for serological surveys, involve finger-prick blood tests of people who haven’t been diagnosed with COVID-19 to gauge the extent to which SARS-CoV-2 has spread undetected. The program relies heavily on automation for screening, with the capacity to screen thousands of individuals daily while keeping costs low.
Since the study launched, SEARCH has enrolled more than 10,000 participants who are asymptomatic or mildly symptomatic. Thus far, researchers have found that an average of two participants per every 1,000 enrolled had a positive result for the SARS-CoV-2 virus.
Participation is voluntary but currently limited to invited healthcare workers from participating hospitals, firefighters and other first responders.
“The majority of our personnel are firefighters and lifeguards who regularly interact with the public and are at a greater risk of exposure to COVID-19. Our goal is for each and every employee to be screened,” says San Diego Fire-Rescue Chief Colin Stowell. “We appreciate the opportunity to participate in the SEARCH study, which benefits our employees and the communities we serve.”
SEARCH is also conducting large-scale SARS-CoV-2 genomic studies, analyzing changes in the virus genome from patient samples for clues to how the disease moved from city to city and person to person. All genomic data gathered by SEARCH is deidentified and then made publicly available to the scientific community to expedite discoveries that will help end the pandemic.
SEARCH’s core research team consists of the following members of the San Diego scientific and medical communities:
- Kristian Andersen, PhD, Professor of Immunology and Microbiology at Scripps Research
- Lauge Farnaes, MD, PhD, Assistant Medical Director at Rady Children’s Institute for Genomic Medicine
- Rob Knight, PhD, Professor of Pediatrics, Bioengineering and Computer Science & Engineering, and Founding Director of the Center for Microbiome Innovation at UC San Diego
- Louise Laurent, MD, PhD, Professor of Obstetrics, Gynecology, and Reproductive Sciences at UC SanDiego School of Medicine
- Gene Yeo, PhD, MBA, Professor of Cellular and Molecular Medicine and Co-Director Bioinformatics and Systems Biology Graduate Program at UC San Diego School of Medicine
The research is made possible by a dedicated team of laboratory staff, postdoctoral researchers, graduate students, nurses, physicians, and volunteers across the partner institutions.
For more information, visit searchcovid.info.
This blog originated as a press release from Scripps Research. Thanks to Scripps and the SEARCH team for permission to post it here.
This blog originated as a press release from Notre Dame News.
As testing for the coronavirus continues throughout the United States, researchers have been closely watching results, particularly reported rates of false negatives.
According to the Radiological Society of North America, a reported 40 to 70 percent of coronavirus tests from throat swab samples returned false negatives at the onset of the epidemic. Given the highly infectious nature of this particular coronavirus, individuals receiving false negative results — told they do not carry the virus when in fact they do — could continue to infect others.
“It is very concerning,” said Hsueh-Chia Chang, the Bayer Professor of Chemical and Biomolecular Engineering at the University of Notre Dame. “In an overcrowded hospital, where there is only room to quarantine the COVID-19 carriers, false negatives would mean some carriers can continue to infect other patients and healthcare workers. This, unfortunately, is also true for other infectious viral diseases such as dengue and malaria, when there is an epidemic. False negatives are usually not an urgent problem, when every symptomatic patient can be quarantined and there are fewer people to infect — until an epidemic overcrowds our hospitals and we have only enough space to sequester the carriers.”
At Notre Dame, Chang’s research lab focuses on the development of new diagnostic and micro/nanofluidic devices that are portable, sensitive and fast. His work includes diagnostics with applications to DNA/RNA sensing. Current coronavirus tests are RNA-based.
Chang said technology his lab developed for other uses could easily be extended to apply to testing for the coronavirus.
“I had developed the technology for isolating cellular material such as vesicles and exosomes during liquid biopsies. They turn out to be the same size as the virus,” he said.
|Dr. Chang at the ERCC2 kickoff meeting in September 2019 discussing his work developing technology to isolate extracellular vesicles.|
The tests combine nanofiltration with immersed AC Electrospray (iACE) digital droplet isothermal polymerase chain reaction (PCR) technology. The nanofiltration part of the test would work to wash away inhibitors while the iACE would allow detection of a very small number of the coronavirus viral particles per sample, improving sensitivity during testing.
Detection can be inhibited at the molecular level, Chang explained. The current tests for coronavirus are PCR-based, a common method that replicates a small sample of RNA — from a nose or throat swab, for example —increasing the number of RNA exponentially in order to identify the presence of the virus and determine the stage of infection.
“The inhibitors, in this case molecules and ions, prevent the reaction from occurring even when the target virus is there, resulting in a false negative,” said Chang. “Our technology removes these inhibitors. There is also the question of yield. In removing the inhibitors, you do not want to lose the target virus as well, so they escape detection. Our technology achieves higher yield in retaining the virus. It extracts the target virus with higher yield and purity than current technology.”
His size-based nanotechnology is especially useful in this case. The coronavirus is between 60 and 140 nm in size. The inhibiting molecules, Chang explained, are smaller than 60 nm, which means he can effectively wash away those particles while retaining the virus.
“The issue is that such small particles often cause clogging and produce high pressure during tests, and break up virus particles, so they’re lost to detection. This is one cause for false negatives,” Chang said. “We already have a patented design that allows filtration of the virus from inhibitors without clogging and without breaking the target virus particles.”
Notre Dame has suspended laboratory research operations across campus with the exception of coronavirus-related research. Chang’s lab is one that received approval to remain operational. Researchers in his lab are not currently working with samples that contain the coronavirus, rather they are testing the technology against a lentivirus serum — a virus that is similar but safe to work with.
“I’m fortunate to have very passionate and capable postdoctoral and Ph.D. students that believe in these technologies and are willing to be in the lab during these trying times,” he said. “Their presence is completely voluntary. In fact, we reduced the number of researchers to three essential people even though several more had volunteered. They abide by very stringent social distancing and lab hygiene rules. They also work in shifts to minimize contact. Another research professor and I are in constant email and cellular communication with them. They are currently testing lentivirus in saliva samples and trying to get more data to back up the numbers.”
The numbers, so far, show that Chang’s test combining nanofiltration with iACE technology are 1,800 times more sensitive in tests run with the lentivirus.
If additional grant funding is approved for his research, Chang said he intends to work with the Centers for Disease Control and Prevention or other Food and Drug Administration approved labs to validate the technology with actual samples containing the coronavirus.
In a white paper outlining the research, Chang set milestones for the work with hopes —if approved — to begin manufacturing devices in six months. However, given the current state of the pandemic, Chang said realistically the technology would be used in cases of future epidemics and outbreaks.
“I think the country is realizing the need for better control of infectious epidemics,” he said. “We hope to develop technology that will help control future epidemics involving any virus or bacteria, not just in the U.S., but especially in the developing world.”