fundamental target genes have been identified and sequenced in the laboratory, the designed primers and probes can be transferred directly to the portable machine format. Many commercially available machines can use the same chemistries, and multiple fluorescent wavelengths should eventually allow multiplex analysis for more than one pathogen per reaction. Also, unlike immunologically based detection methods, fluorescent primers and probes can be altered slightly to accommodate known genetic changes, without having to regenerate and revalidate as with serum-based reagents.

Agricultural Biological Threat Agents

Although agriculture does not immediately come to mind when one considers biowarfare or bioterrorism, every nation that has had a biological warfare program has had an anti-animal and an anticrop component (Rodgers et al., 1999; Wilson et al., 2001). Thus a number of potential threats have been identified for both animals and plants. Expert panels have been convened in recent years to determine attributes most likely to contribute to effectiveness of a bioweapon, and oftentimes the agents have then been ranked. Table 5-2 is a working top ten list of animal pathogens that have been used by the Agricultural Research Service in the last 2 years as a guide for developing detection reagents. At least four of these listed organisms (foot-and-mouth disease [FMD] virus, Newcastle disease virus [NDV], hog cholera virus, and Rinderpest) have been weaponized at one time in the past and evaluated under field conditions (Wilson et al., 2000). Since many of the animal commodity groups, including poultry, are clustered in high concentrations in various regions of the country, the possibility of an event of widespread introduction is high. The reasons for potential purposeful introductions are many and varied, and unfortunately it is not difficult to think of scenarios resulting in purposeful introduction of biological agents into the poultry industry. Thus, we must remain vigilant. The regulatory agencies that would respond to introduction of foreign animal diseases are likely capable of handling a single introduction (Ginsburg, 2000), although the recent FMD outbreak in the United Kingdom clearly illustrates the potential devastating effects of just a single entry point of a highly infectious foreign animal disease. A concerted attack on U.S. poultry with multiple introductions would almost certainly paralyze the industry even with the best efforts of the regulatory agencies.

Avian Influenza A Viruses as Potential Bioweapons

Highly pathogenic avian influenza viruses are generally found on all the lists of potential agricultural bioweapons. Like virulent Newcastle disease viruses that have been weaponized in the past, the AI viruses can be highly



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