New single virus detection techniques for faster disease diagnosis

Researchers at the Conference on Lasers and Electro-Optics describe optical techniques for counting individual viruses outside the lab

2013-05-30

(Press-News.org) To test the severity of a viral infection, clinicians try to gauge how many viruses are packed into a certain volume of blood or other bodily fluid. This measurement, called viral load, helps doctors diagnose or monitor chronic viral diseases such as HIV/AIDS and hepatitis. However, the standard methods used for these tests are only able to estimate the number of viruses in a given volume of fluid. Now two independent teams have developed new optics-based methods for determining the exact viral load of a sample by counting individual virus particles. These new methods are faster and cheaper than standard tests and they offer the potential to conduct the measurements in a medical office or hospital instead of a laboratory. The teams will present their latest results at the Conference on Lasers and Electro-Optics (CLEO: 2013), to be held June 9-14, in San Jose, Calif.

One research group, led by electrical engineer and bioengineer Aydogan Ozcan of UCLA, is working to directly image single virus particles using holographic microscopy. The other, led by electrical engineer Holger Schmidt of the University of California, Santa Cruz (UCSC), is detecting single particles tagged with fluorescent labels on a microfluidic chip. Both teams expect to use their work to develop commercial instruments useful for on-site diagnosis and monitoring with rapid results and fast turnaround.

Ozcan's UCLA team has demonstrated the ability to capture optical images of single viruses and nanoparticles over a comparatively large field of view – about the size of a postage stamp – using nanolenses that self-assemble around the virus particles like little magnifying glasses.

"Because viruses are very small--less than 100 billionths of a meter--compared to the wavelength of light, conventional light microscopy has difficulty producing an image due to weak scattering of sub-wavelength particles," Ozcan says. When lighted, the team's new nanolens-nanoparticle assembly projects a hologram that can be recorded using a CMOS imager chip (a type of semiconductor-based light detector) and digitally reconstructed to form an optical image of the particle. "The resulting image improves the field-of-view of a conventional optical microscope by two orders of magnitude," says Ozcan.

This wide field of view allows the device to form images of many nanoparticles in a single photograph and provides a high-throughput platform for a direct and accurate viral load count. The instrument can be made sufficiently compact and lightweight for field applications and, attached to a cell phone, could become useful even in remote locations.

The UCSC researchers will present the results of a collaborative effort between UCSC, Liquilume Diagnostics Inc., and the groups of infectious disease clinician and virologist Charles Chiu at University of California, San Francisco, and engineer Aaron Hawkins at Brigham Young. While Ozcan's group visually counts individual viruses, Schmidt's counts them by detecting their nucleic acids--the genetic makeup of the viruses. The nucleic acids are labeled with a fluorescent dye, and light from the fluorescence is detected as they pass through a channel in a microfluidic chip about the size of a thumbnail.

Current tests for determining viral load generally rely on a technique called polymerase chain reaction (PCR), which amplifies a small sample of nucleic acid, such as DNA, and makes it easier to detect. "The gold standard for viral load detection is PCR, due to its sensitivity and specificity," Schmidt says, but PCR is limited to merely estimating the number of viruses. In contrast, the new method counts real particles as they pass through the fluorescence detector on the chip. "We have demonstrated actual virus counts of specific nucleic acids in less than 30 minutes with minimal sample workup," Schmidt says. So far, the group has collected reliable data on samples diluted to a point well within the range required for clinical detection.

Unlike direct visualization techniques, Schmidt's chip-based method requires that the targeted virus particles be labeled. The labeling technique would allow clinicians to target specific viruses while ignoring unlabeled background material. This makes the process potentially useful in situations where clinicians already know what they are looking for – often the case for viral load tests.

The chip is currently housed in an instrument about one foot square, making the device portable. Along with rapid analysis turnaround, this portability should make the technique useful for point-of-treatment tests. In addition to detecting viruses, the device may also find uses as a sensor for cancer biomarkers, for environmental analyses of chemicals, and even in industrial production monitoring.

INFORMATION:

CLEO: 2013 presentation AW1I.6. "High-throughput Imaging of Single Viruses using Self-assembled Nano-lenses and On-Chip Holography" by Aydogan Ozcan will take place Wednesday, June 12 at 12:15 p.m. in the San Jose Convention Center.

CLEO: 2013 presentation CM1M.7. "Clinical Detection of Viral Infection on an Optofluidic Chip" by Philip Measor will take place Monday, June 10 at 9:45 a.m. in the San Jose Convention Center.

EDITOR'S NOTE: High-resolution images are available upon request. Contact Brielle Day, bday@osa.org

Press Registration

A Press Room for credentialed press and analysts will be located on-site in the San Jose Convention Center, June 9 - 13. Media interested in attending the conference should register on the CLEO website or contact Brielle Day at 202.416.1435, bday@osa.org.

About CLEO

With a distinguished history as the industry's leading event on laser science, the Conference on Lasers and Electro-Optics (CLEO) is where laser technology was first introduced. CLEO unites the field of lasers and electro-optics by bringing together all aspects of laser technology, with content stemming from basic research to industry application. CLEO: Expo showcases the latest products and applications from more than 300 participating companies from around the world, providing hands-on demonstrations of the latest market innovations and applications. The Expo also offers valuable on-floor programming, including Market Focus and the Technology Transfer program.

Sponsored by the American Physical Society's (APS) Laser Science Division, the IEEE Photonics Society and the Optical Society (OSA), CLEO provides the full range of critical developments in the field, showcasing the most significant milestones from laboratory to marketplace. With an unparalleled breadth and depth of coverage, CLEO connects all of the critical vertical markets in lasers and electro-optics. For more information, visit the conference's website at http://www.cleoconference.org.

ELSE PRESS RELEASES FROM THIS DATE:

Soccer training improves heart health of men with type 2 diabetes

2013-05-30

A new study from the Copenhagen Centre for Team Sport and Health at the University of Copenhagen, Denmark, demonstrates that soccer training improves heart function, reduces blood pressure and elevates exercise capacity in patients with type 2 diabetes. Soccer training also reduces the need for medication. The study, recently published in Medicine & Science in Sports and Exercise, investigated the effects of soccer training, consisting of small-sided games (5v5), on 21 men with type 2 diabetes, aged 37-60 years. Soccer training makes the heart ten years younger "We ...

When friends create enemies

2013-05-30

PITTSBURGH—The mutual-friends feature on social networks such as Facebook, which displays users' shared friendships, might not be so "friendly." Often revered for bringing people together, the mutual-friends feature on Facebook actually creates myriad security risks and privacy concerns according to a University of Pittsburgh study published in Computers & Security. The study demonstrates that even though users can tailor their privacy settings, hackers can still find private information through mutual-friends features. "Oftentimes, mutual-friends features have not ...

UGA research uncovers cost of resiliency in kids

2013-05-30

Athens, Ga. – Children living in poverty who appear to succeed socially may be failing biologically. Students able to overcome the stress of growing up poor are labeled "resilient" because of their ability to overcome adversity, but University of Georgia researchers found this resiliency has health costs that last well into adulthood. "Exposure to stress over time gets under the skin of children and adolescents, which makes them more vulnerable to disease later in life," said Gene Brody, founder and director of the UGA Center for Family Research. Looking at a sample ...

Young people are overwhelmingly the victims of sexual assaults

2013-05-30

Sexual assault has almost as much to do with age as it does with gender, according to Penn State criminologists. Young people -- both male and female -- are the most likely targets of rape and other sexual assaults, said Richard Felson, professor of criminology and sociology. The most frequent victims of those assaults are 15 years old, regardless of gender, or the age of the offender, he said. Older people and women rarely commit the crime, but when they do, their most frequent victims are still 15 years old. "People tend to look at sexual assault almost exclusively ...

New York City successfully locates HIV-positive patients 'lost to follow-up'

2013-05-30

Philadelphia, Pa. (May 30, 2013) – Public health officials in New York City have launched a successful program to locate HIV-positive patients who have been "lost to follow-up" and reconnect them with treatment services, reports a study published in AIDS, official journal of the International AIDS Society. AIDS is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health. Efforts to restart antiretroviral therapy are especially important with the current emphasis on "treatment-as-prevention" for HIV, according to the study by Chi-Chi N. Udeagu, MPH, ...

Fast-food restaurants near schools affect black and Hispanic students more than white and Asian ones

2013-05-30

When their schools are near fast-food restaurants, black and Hispanic adolescents are more likely to be overweight and receive less benefit from exercise than Asian or white students, according to a study published in the current issue of Journal of Public Policy & Marketing. The study underscores the importance of understanding how adolescents respond to fast-food availability near school. "Our study demonstrates that fast food near schools is an environmental influence that has magnified effects on some minority children at lower-income urban schools," said Brennan ...

Farmland fires in Angola

2013-05-30

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite detected hundreds of fires burning in Angola on May 24, 2013. The fires are outlined in red. Most of the fires burn in grass or cropland. The location, widespread nature, and number of fires suggest that these fires were deliberately set to manage land. Farmers often use fire to return nutrients to the soil and to clear the ground of unwanted plants. This type of field clearing is the easiest and most cost effective for the farmer. While fire helps enhance crops and grasses for pasture, ...

Low doses of THC can halt brain damage

2013-05-30

Though marijuana is a well-known recreational drug, extensive scientific research has been conducted on the therapeutic properties of marijuana in the last decade. Medical cannabis is often used by sufferers of chronic ailments, including cancer and post-traumatic stress disorder, to combat pain, insomnia, lack of appetite, and other symptoms. Now Prof. Yosef Sarne of Tel Aviv University's Adelson Center for the Biology of Addictive Diseases at the Sackler Faculty of Medicine says that the drug has neuroprotective qualities as well. He has found that extremely low doses ...

Study: Pedometer program helps motivate participants to sit less, move more

2013-05-30

Indiana University researchers found that a simple program that uses pedometers to monitor how much people move throughout the day was effective at increasing physical activity, decreasing sitting time, a particular problem for office workers, and helping participants drop some pounds. "Even if somebody works out 30 minutes a day, the fact that they're sitting and not moving for long periods of time for the rest of the day is in and of itself detrimental to their health and well-being, physiologically," said Saurabh S. Thosar, an associate instructor at the IU School ...

NASA sees Hurricane Barbara quickly weaken to a depression

2013-05-30

Tropical Storm Barbara strengthened into a hurricane just before it made landfall late on May 29, and after landfall it weakened into a tropical depression. NASA satellite imagery showed that cloud tops warmed and thunderstorms became more fragmented around the storm's center after Barbara made landfall. Barbara is moving across the Isthmus of Tehuantepec today, May 30. Barbara could regenerate over the Bay of Campeche, on the Gulf of Mexico side of Mexico, and satellite imagery is watching Barbara closely. The Bay of Campeche is surrounded on three sides by the Mexican ...

New single virus detection techniques for faster disease diagnosis

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: