Viral biology

DEFINITION: Subspecialty of biology that focuses on viruses, tiny nonliving microbes that serve as receptacles for nucleic acids (RNA or DNA) and are dependent on prokaryotic or eukaryotic hosts for replication.

SIGNIFICANCE: Viral biologists have knowledge of the structure, genetics, and replication of viruses as well as the skills needed to identify associated viral pathology. These skills are becoming increasingly significant to forensic science, given growing threats of biocrime, acts of bioterrorism, and emerging and reemerging viral diseases. The domains of viral biology and forensic science appear to overlap in the areas of biosecurity and epidemiology of infectious disease.

In contrast to the epidemiological and diagnostic requirements of public health and private practice, respectively, microbial forensics (the branch of forensic science that deals with microorganisms) demands more detailed characterization of microbes in order to determine the origins of pathogens or toxins (identification) and who or what organizations were responsible for their dissemination (attribution). Microbial forensic scientists use genetic and nongenetic assays to attribute a source or to discount one and to determine whether an event occurred naturally (for example, through the spread of an infectious disease) or as the result of an inadvertent release of a toxin or pathogen, a biocrime, or an act of bioterrorism.

Methods and Technologies

Forensic microbiological investigations are essentially similar to standard forensic investigations in that they involve investigation, attention to chain of custody, and strict adherence to protocols for collection, preservation, and shipping. The evidence samples analyzed in relation to a suspected biocrime or act of bioterrorism may include liquids, powders, and organic matter as well as fingerprints, hair, and fibers. Given that the goal is to provide for use in legal proceedings, an effective microbial forensics program mandates validation of each step in the investigation, from sample collection to interpretation of results, in order to guarantee that quality-assurance practices are being implemented.

In 1999, when West Nile virus disease was found in the state of New York, apparently the first time it had occurred in the United States, authorities worried that a biocrime had been committed. Microbial forensic techniques helped scientists determine that the emerging West Nile virus disease had been spread by mosquitoes and was a natural occurrence. The technologies scientists use in such cases include Polymerase chain reaction (PCR) assays, which amplify samples, and sequencing to identify pathogens. Information obtained from PCR and sequencing of nucleic acids may then be evaluated through phylogenetic studies, which are used to infer relationships between organisms and may help characterize novel viral strains, as was demonstrated in 1999 when a new strain of the human immunodeficiency virus (HIV) was identified in Africa.

Phylogenetic studies may also help determine whether a viral strain was introduced through negligent or criminal action. For example, forensic scientists were able to identify the source of an HIV infection in a case of sexual abuse of a child even after several years had passed; they compared the nucleotide sequences of the child with those of her abuser and found that the strain of HIV was the same. (Deoxyribonucleic acid, or DNA, and ribonucleic acid, or RNA, are composed of nucleotides.) Previously, a group of hemophiliac patients who had received pooled blood plasma and were later infected with HIV were shown to have been infected from the same source—that is, contaminated plasma. In another case, genetic analysis showed that a New Jersey dentist and five of his patients harbored the same strain of HIV, indicating that the dentist was the source of the infection.

Bioterrorism and Emerging Viral Diseases

Advances in sanitation, the discovery of vaccines for diseases such as smallpox, and, in the early 1940’s, the development of penicillin as an antibiotic resulted in growing optimism in the public health community that infectious disease—the number one killer worldwide—would soon be controlled. In the late twentieth century, however, the world began to experience the greatest pandemic of all time, that of HIV and acquired immunodeficiency syndrome (AIDS). Within less than three decades, approximately fifty million persons had been infected worldwide and twenty million were dead, and HIV/AIDS, along with its cohort, tuberculosis, threatens to kill hundreds of millions more. Molecular epidemiologists are focusing on understanding drug-resistant strains of HIV and tuberculosis so that they can discover ways to combat them. Virologists are studying the blood from survivors of the catastrophic influenza epidemic of 1918 to understand why the flu was so deadly and to prepare for the possibility of another pandemic caused by the avian influenza virus H5N1.

At no time in history has the dilemma of the application of science for either the good or the detriment of humankind been more apparent as the specters of bioterrorism and emerging viral diseases underscore the need for biosecurity and biosurveillance around the world. (Emerging viral diseases may be caused by previously unknown viruses or by known viruses that have newly appeared or reappeared in particular locales or populations or have mutated, become drug-resistant strains, or developed new modes of transmission.) The National Institute of Allergy and Infectious Diseases (NIAID) has categorized agents responsible for the emergence and reemergence of highly virulent and contagious infectious viral diseases across the globe and has classified a host of pathogens as “agents with bioterrorism potential,” including Ebola and Marburg hemorrhagic viruses, the smallpox virus and related pox viruses, hantaviruses, Lassa virus, and bacteria such as Bacillus anthracis (which causes anthrax) and Yersinia pestis (which causes plague), all of which may be weaponized.

The Laboratory Response Network—involving the Centers for Disease Control and Prevention (CDC), the Association of Public Health Laboratories, and the Federal Bureau of Investigation (FBI), with links to laboratories across the United States—was created specifically to respond to acts of bioterrorism and outbreaks of emerging infectious disease. In 2003, the U.S. Department of Homeland Security launched the National Bioforensic Analysis Center to serve as a resource for the analysis of microbial evidence derived from acts of bioterrorism.

In 2016, a study showed that viruses have traceable geographic distributions. This allows investigators to use viral forensics to trace an individual's travel history.

Bibliography

Budowle, Bruce, et al. “Quality Sample Collection, Handling, and Preservation for an Effective Microbial Forensics Program.” Applied and Environmental Microbiology 72 (October, 2006): 6431-6438.

Budowle, Bruce, Randall Murch, and Ranajit Chakraborty. “Microbial Forensics: The Next Forensic Challenge.” International Journal of Legal Medicine 119 (November, 2005): 317-330.

Carter, John B., and Venetia A. Saunders. Virology: Principles and Applications. Hoboken, N.J.: John Wiley & Sons, 2007.

Ellison, D. Hank. Handbook of Chemical and Biological Warfare Agents. 2d ed. Boca Raton, Fla.: CRC Press, 2007.

Lederberg, Joshua, ed. Biological Weapons: Limiting the Threat. Cambridge, Mass.: MIT Press, 1999.

Nathanson, Neal. Viral Pathogenesis and Immunity. 2d ed. Burlington, Mass.: Elsevier Academic Press, 2007.

Santos, Raquel. "The Role of Forensic Virology in Crime Investigation." Medium, 3 Nov. 2022, medium.com/pasteurs-quadrant/the-role-of-forensic-virology-in-crime-investigation-1049fe71e708. Accessed 19 Aug. 2024.

Yuan, Huiya, et al. "Trends in Forensic Microbiology: From Classical Methods to Deep Learning." Frontiers, 29 Mar. 2023, www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1163741/full. Accessed 19 Aug. 2024.