The Science of Detecting Terror - ACS Publications

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A N A LY T I C A L C H E M I S T R Y / M A R C H 1 , 2 0 0 2

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The Science of Detecting Ter ror Amid patriotism, politics, and research money, analytical chemists face new challenges in the fight against biological and chemical - war fare.

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n any other ordinary year, David Walt?s symposium on Detection of Terrorist Weapons at this month?s Pittcon 2002 in - New Or leans, La., would be business as usual. But these times are be yond ordinary. The chemistry professor at Tufts University in Medford, Mass., has

Cheryl M. Harris

M A R C H 1 , 2 0 0 2 / A N A LY T I C A L C H E M I S T R Y

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Hazardous materials experts enter the Hart Building of the U.S. Senate on November 7, 2001, in Washington, D.C. The Hart Building was closed after an anthraxlaced letter was found in Senator Tom Daschle’s office.

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worked for 20 years in the field of sensor and detection systems for biological warfare (BW) and chemical warfare (CW) agents. He had planned the symposium at the Morial Conven tion Center a year ago well before September 11 and it had attracted anticipated interest but modest fanfare. Now, I?m getting calls from the Pittcon organizers that they?re high lighting this and scheduling press conferences and everything, says Walt.

Many analytical chemists are seeing their research get more attention since the September 11 assaults and the anthrax attacks that followed. Others are asking, “What can we do to help?” Richard Meyer, director of the Bioterrorism, Rapid Response, and Advanced Technology Laboratory at the Centers for Disease Control and Prevention (CDC) based in Atlanta, Ga., saw a surge of calls pitching the latest counter-bioterrorsim technology after September 11. Before then, his phones had been nearly silent. “It amazed me how in the past couple of months there’s been such a tremendous scientific breakthrough in the area of anthrax diagnostics,” says Meyer, a microbiologist. “I’ve had virtually hundreds of calls from everyone saying, ‘I’ve got the better mousetrap.’ … We had to actually set up an office that was

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handling those calls because we had so many.” September 11 and the five anthrax deaths, which began with the death of a Florida news photographer in October, have changed the United States’ sense of security. These events have evoked patriotism among citizens, including many analytical chemists who have the expertise—from MS to microfluidics— to find ways of protecting the country. In November, the Science Advisory Board, an online panel of more than 6000 scientists, physicians, and other life science professionals from 62 countries, announced a survey in which more than 1900 website visitors were asked what they thought would be the best scientific investment for fighting bioterrorism. Forty-five percent believed allocating resources to developing rapid and sensitive diagnos-

tics, 32% said generating prophylactic vaccines, 15% said new therapies, and 8% said “other”. Americans are realizing that unlike the 1991 Gulf War, which made BW and CW household terms, the threat is now at their front door. The U.S. government and its citizens want solutions. Meanwhile, researchers who have worked in the field of BW/CW agent detection face concerted interest from the government. They must grapple not only with developing the technology but also with the politics and intense emotions that have wrapped themselves around the science of detecting terror.

A call to arms and federal funding Among the researchers who feel a duty to contribute is Allen


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Northrup, founder, president, and chief executive officer of Microfluidic Systems, Inc. (MFSI) in Berkeley, Calif. The company specializes in, among other things, automated, integrated instruments for environmental monitoring and military and civilian biodefense. “I think that there’s a real sense that we kind of owe it to the country,” says Northrup. “We’ve all been basically drafted, especially the people who’ve been getting the [research] money all these years.” Other researchers describe how they want to work harder on new sensors and detection systems. “As a researcher, … I’m more anxious to do more,” says Touradj Solouki, an assistant professor at the University of Maine in Orono. “You can do things defense-related, and then you can come up with answers that are … also for public health.” Some, like Walt, see the need for scientists to work together. “I think unless we move into a Manhattan Project-type of environment, where all scientists are going to be called to government service, … as a community we are obligated to participate in this effort.” The terrorist attacks also prompted immediate action from government officials and agencies. In November, U.S. Homeland Security Director Tom Ridge attended a Department of Energy counter-terrorism technology exposition in Washington, D.C., that showcased various chemical- and biodetection devices from more than 10 national laboratories. Technologies included a holographic imaging system for airport screening, an automated sample preparation system that breaks apart samples for pathogen detectors (1), polymer-coated surface acoustic wave sensors to detect chemical vapors (2), and decontamination foam for anthrax and other BW/CW agents. Just before adjourning for the year in December, the U.S. Congress approved $8.3 billion from an allocated $20 billion Department of Defense (DoD) spending bill to improve domes-

tic security. According to reports, more than $3.5 billion is earmarked to counter bioterrorism. Other features of the bill include protecting the U.S. food supply. Despite the new emphasis on combating BW/CW, government research agencies, such as the Naval Surface Warfare Center, the Naval Research Laboratory, and the Defense Advanced Research Project Agency (DARPA)—all under DoD—are divulging little if any information about their latest research. DARPA officials, for instance, would not comment on whether the agency is collaborating with researchers outside the United States, and they would not specify how many calls from researchers the agency received right after September 11. “When [researchers] feel that they have a technical idea that can help, they are contacting the government about their idea,” says Jan Walker of DARPA’s external relations department. “DARPA is receiving some of these calls; it is likely that other federal agencies are as well.” DARPA, which has two programs under its belt— tissue-based biosensors and biosensor technologies—requested $30 million in funding for this year, she says. Last year, $24 million was funded to the agency, which primarily focuses on BW defense rather than CW defense, says Walker. Federal officials have advised some scientists not to talk to the media, and there are those who are talking but choosing their words carefully to protect their work. “I think the scientific community, like the rest of America, wants very much to help,” says Catherine Fenselau, a professor of biochemistry at the University of Maryland in College Park. “And we need to be coordinated in doing so. Some of us need to be funded.” But with money comes responsibility, and some analytical chemists are asking themselves what will really be the outcome of September 11 in sensor and detection research.

COURTESY OF THE U.S. DEPARTMENT OF ENERGY

The Department of Energy’s counter-terrorism technology exposition held in Washington, D.C., drew the attention of top U.S. officials. Mark Tucker of Sandia National Laboratory shows U.S. Homeland Security Director Tom Ridge how decontamination foam works to neutralize BW/ CW agents.

Searching for solutions Soon after the first anthrax death in Florida, Walt got the call from government officials. He packed his bags and headed for the nation’s capital to meet with them. “People began to scramble to put some things together in terms of what are our present capabilities and what were the future prospects in terms of being able to address some of these kinds of threats,” recalls Walt. But for Walt, an expert in the area of high-density optical arrays who has served on several advisory groups for federal agencies, such scrambling causes some worry. He and other researchers are carefully watching how the government will encourage and coordinate good, feasible science from universities or private companies for detecting BW/CW agents. Northrup and Bill Nelson, who is president of Tetracore, Inc., in Gaithersburg, Md., a biotechnology research and development laboratory that produces diagnostic reagents and assays for infectious diseases and BW threat agents, see an opportunity for the commercial sector to receive government funding and get more involved. Tetracore and MFSI, both incorporated in the past few years, have established a partnership to produce and commercialize “detect-to-warn” and “detect-to-treat” sensors. The technology that’s being used today directly comes from government funding, says Northrup. Government officials, he says, should “reach down” into what’s already been developed

the kind of time frame that people need to realistically think about in terms of solving this particular challenge,” he says. Researchers also understand that competition over research money and bureaucratic control are realities for any scientist. “I think that if it’s coordinated through the funding agencies, which have review processes, we’ll pick out the best stuff, the proposals with highest potential,” says Fenselau. All the scientists interviewed agreed that every field, from particle physics and engineering to chemistry and microbiology, that has the potential to contribute to BW/CW agent detection should be considered. The effort needs to be integrated and multidisciplinary, they say. In the 1991 Gulf War, explain researchers, battlefield detection systems were limited to benchtop, enzyme-linked immunosorbent assays (ELISAs) and portable antibody-based chromatographic assays, which are described as “relatively primitive,” by Walt and David Franz, who is vice president at the Chemical and Biological Defense Division for the Southern Research Institute in Frederick, Md., a not-for-profit affiliate of the University of Alabama at Birmingham (3). Today, detection devices are based primarily on immunochemistry and range from hand-held devices to expansive “labs on wheels”. For example, the Biological Integrated Detection System requires a generator and all-terrain vehicle; the Long-Range Biological Standoff Detection System is

Unfortunately, researchers haven?t reached the of detecting BW agents in real time. and done successfully. “My concern, and this is more of a business side thing, is … let’s make sure that it doesn’t become politicized,” adds Northrup. Northrup and Nelson say the downside is there will likely be “pie-in-the-sky” projects that will steal funding and attention from legitimate research. Nelson, however, goes further in his concerns. He says the CDC put together a program that’s mostly “in-house” rather than one that looks outside its institution to see what’s available. “I think they really bogged down the system by not going [outside the CDC],” he says. “There isn’t enough openness in terms of looking at some of the solutions.” He adds that when vying for contract research with the government, “it’s really knowing people as opposed to having an opportunity.” Meyer refutes any claims that the CDC exclusively uses inhouse methods or evaluations. “We’ve been totally open and seek out people who have good technology and good science,” he says. Officials are working with a lot of different groups, government and private, and one product CDC officials are evaluating is from Tetracore, he says. Researchers in academia have similar worries about how funding will be distributed. Walt encourages government officials to not rush into things, saying they should seek the advice of experts about what’s possible and what’s not in order to “separate the wheat from the chaff.” “The 5- to 10-year time frame is clearly

a rapid, continuous aerosol detection system for early warning; and the Portal Shield uses immunochromatographic hand-held assays (HHAs). Overall, says Franz, “we really have three options. We have antibody-based assays, like the ELISAs, we have nucleic acid-based assays … and then we have ‘mass spec’ approaches.” The future of BW detection, according to Walt and Franz, will rely on four principles: measuring particles by shining light or using sunlight to illuminate samples, detecting specific agents or toxins by various immunoassays, amplifying DNA by polymerase chain reaction (PCR) and then detecting results with specific gene probes, and using MS to detect various BW agents. Many such systems continue to be candidates for BW/CW agent detection, says Walt, including immunoassays, methods that combine PCR with DNA-type array systems, and MS techniques. Real-time PCR with fluorescence detection is being implemented, and integrating sample analysis and miniaturization is also being investigated, he adds. Private companies, such as Tetracore and MFSI, have come up with their own techniques. While Tetracore offers antibodybased tests—immunochromatographic assays that perform like home pregnancy test kits and can be taken out onto the field— MFSI sells microfluidic-based sample processing systems to support those assays and DNA-based assays. During the anthrax investigations, officials at the CDC rapidly screened for Bacil-


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lus anthracis contamination at the Brentwood postal facility in Washington with real-time PCR-based devices and time-resolved fluorescence (TRF) antigen detection assays. The specimens were then cultured, and an algorithm that relies upon a few tests—one being a direct fluorescence antibody test and another a gamaphage analysis that’s very specific for B. anthracis—was used to confirm anthrax, says Meyer. The real-time PCR and the TRF are being used as rapid screening tests at this point, says Meyer, “even though [those tests] have an extremely high confidence level and have correlated 100% with the confirmatory test over the course of the investigation.” He adds that although the CDC’s assay is not approved by the Food and Drug Administration, which is why it’s used only as a screening assay, “we have a very well-defined, worked-out plan for testing, and we’ve been following it, and it has worked very well.” However, Meyer adds, CDC officials are more cautious about HHAs, which they say are not as sensitive as laboratory-based tests, are not specific enough, and require a fair amount of organisms present for a positive reaction. “The hand-held assays, we don’t know how well they perform. That’s why we are in the process of an FBI [Federal Bureau of Investigation]-sponsored study. This is a six-month study to take a good, thorough look at these hand-held assays.” Unfortunately, says Franz, researchers haven’t reached the level of detecting BW agents in real time. Other obstacles to overcome for BW agent detection are automating these systems to minimize user intervention, improving detection limits and accuracy, and developing systems that consume little power and

way in 1995, when the Japanese religious cult Aum Shinrikyo unleashed the organophosphate nerve gas sarin on commuters, killing 11 and injuring more than 5000. Victims reacted quickly, making it obvious who was ill, says Franz. “But with biological [agents], I think there is a big psychological overlay because it’s hard to triage and find out who was exposed before they show clinical signs.” An MS method comes closest to being almost reagentless and a timely chemical assay, says Franz. The problem, however, is that one would have to, for example, know in advance the spectrum that uniquely identifies anthrax, he adds. In December, Metropolitan Area Transit Authority (Metro) safety officials in Washington, D.C., installed various unnamed chemical sensors at selected, undisclosed Metro stops. “We’ve been testing the devices for a couple of years now … and they have performed to our satisfaction,” says Metro spokesperson Cheryl Johnson. Once the technology is available, BW agent detectors will be installed, she says. Officials estimate the cost of installing chemical sensors at 47 underground locations along the Metro rail line at $81 million. Such quick measures perplex researchers like Nelson. He says he hasn’t seen a chemical sensor yet that’s specific and fully automated enough to detect a threat without giving out false-positive alarms. “It sounds like a great idea,” he says. “[But] I don’t know that we are currently capable of implementing it in a rational manner. … Will they be turned off all the time because they have too many false alarms?” Maybe in the future these sensors could be useful, Nelson adds, “but this is one of those things where they may be rushing to spend enormous amounts of money.”

We can invent a great analytical chemistry pri and it?s still got to be engineered into someth no reagents. Today’s systems, with occasional false-positives and long response times, do not meet the “detect to warn” needs for soldiers or civilians. Walt says the goal is now designing “detect to treat” devices for civilians. In spite of the limitations of today’s systems, researchers are hopeful about the future. If scientists continue to make headway in sensor and detection research, installing advanced BW agent alarm systems in places like post offices will be possible, says Northrup. So far, says Fenselau, the PCR-based methods being used are impressive, but there’s a need for something faster and more sensitive. “Those folks have done a real good job of getting the speed of PCR down to maybe 30 minutes,” she says, “but that’s still 30 minutes … One of the other challenges for analytical chemistry is the 2-minute turn around.” Researchers add that the technical challenges in creating detection systems for BW agents are harder than those for CW agents. Chemical agents are volatile enough for almost immediate detection, say experts. Such was the case in a Tokyo sub-

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There are also logistical problems in BW/CW agent detection, say experts. There are areas of the country at higher risk than others, and Franz wonders who will decide where these sensors will be installed. “I don’t think my mother in Kansas needs a biological detector in the retirement center,” he says. And an outdoor attack is much more difficult to do than an attack inside a building, with heat and air conditioning ventilation systems, say researchers. When a BW agent is deployed outside as an aerosol, its effectiveness will depend on the environment, says Franz. In a city, for example, there are thermals that cause turbulence and make it difficult to lay a uniform cloud across a city. Another problem is taking a scientific method and applying it on a larger scale for civilian communities. Some researchers are optimistic that the technology to address these problems is well on the way, but, adds Fenselau, “We can invent a great analytical chemistry principle, and it’s still got to be engineered into something … that doesn’t have to be attended, that has computer reporting.”

COURTESY OF THE U.S. DEPARTMENT OF ENERGY

Jay Grate of Pacific Northwest National Laboratory explains the science behind the surface acoustic wave sensor to U.S. Homeland Security Director Tom Ridge during the Department of Energy’s counter-terrorism technology exposition in Washington.

Government officials are also reevaluating their response procedures to BW/CW threats. When two employees from the Brentwood post office in Washington died after a series of anthrax-contaminated letters had arrived on the desks of legislators and news organizations, the CDC was blamed for underestimating the danger to workers. In the agency’s defense, CDC Director Jeffrey Koplan said in late October that officials had assumed that “the concept of a powder in a sealed letter was one that suggested that it would stay in that letter.” CDC officials are now reevaluating a common guide of infective dose requirements of selected aerosol BW agents, which, researchers say, was based mostly on military studies on animals. There needs to be more research, says Meyer. For example, it’s thought that 8000–10,000 inhaled spores can cause anthrax infection and only 10–100 organisms are required to develop smallpox. “Certainly with the anthrax situation that has occurred, we question, for example, the number of spores needed as an infectious dose by aerosol,” says Meyer. “We certainly saw that during the anthrax investigations, [it] certainly seemed like people might have been exposed to much lesser doses.” Investigators agree that might be the case in the anthrax deaths of two women in Connecticut and New York City. Although the CDC seems to have become a lightening rod for the government’s miscalculations with anthrax, Meyer says that contrary to media reports that CDC laboratories were in chaos—a matter that has frustrated him—its scientists were well prepared. A laboratory response network set up in 1998 that includes the FBI and the Association of Public Health Laborato-

ries established a direct line of communication to all the members, he says. “This was an unprecedented situation where the public health system had never seen this type, this volume, of material,” he says. “It was handled quite well.” At least 45,000 specimens were collected throughout the investigation, with the CDC looking at more than 7000, he says. And Meyer says U.S. Department of Agriculture (USDA) officials didn’t do the testing, which some may have believed, because their technology isn’t that far advanced, he says. “I used to work for the USDA for 10 years, and believe me, they are lagging behind in playing catchup right now … for [detecting] biological agents.”

Finding common ground In a November 1997 televised press conference, former Defense Secretary William Cohen dramatically held up a sack of sugar and said that with an equivalent amount of anthrax, Iraq could eliminate at least half of the population of Washington, D.C. “That was the introduction to the American public,” says Franz, “although the Department of Defense had been thinking about these things for a long time, and with heightened interest after the Gulf War.” If Cohen’s bag of sugar was the wake-up call for Americans— six years after the 1991 Gulf War, where BW/CW warfare was an ever-present reality to soldiers—was the government fully prepared for a civilian attack? “I think we believed that we faced certainly a future threat on the battlefield … and we took it seriously to that extent,” says Franz, once commander and deputy commander of the U.S. Army Medical Research Institute of Infectiouse Diseases. “I’m


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The Science of Detecting Terror - ACS Publications

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