The evolving field of biodefence: therapeutic developments and diagnostics.

The threat of bioterrorism and the potential use of biological weapons against both military and civilian populations has become a major concern for governments around the world. For example, in 2001 anthrax-tainted letters resulted in several deaths, caused widespread public panic and exerted a heavy economic toll. If such a small-scale act of bioterrorism could have such a huge impact, then the effects of a large-scale attack would be catastrophic. This review covers recent progress in developing therapeutic countermeasures against, and diagnostics for, such agents.

Modification of dengue virus strains by passage in primary dog kidney cells: preparation of candidate vaccines and immunization of monkeys.

Dengue (DENV) virus strains for each of the four DENV serotypes were modified by passage in primary dog kidney (PDK) cell cultures with final manufacture of vaccine lots in fetal rhesus monkey diploid cell cultures. "Strain sets" consisting of serially-passaged DENV were inoculated in rhesus monkeys along with unmodified parent viruses for each strain. Vaccine candidates were compared with unmodified parent viruses by measuring viremia and immune responses. All except one DENV-1 strain demonstrated reduced infection in monkeys after PDK cell passage. A DENV-3 strain lost all monkey infectivity after PDK cell passage. Twelve vaccine candidates were selected for Phase 1 human trials through this selection process.

Implementation of biosurety systems in a Department of Defense medical research laboratory.

New biosurety regulations and guidelines were implemented in 2003 because of increased concern for the safety and security of biological select agents and toxins (BSAT) that may be used as weapons of mass destruction. Biosurety is defined as the combination of security, biosafety, agent accountability, and personnel reliability needed to prevent unauthorized access to select agents of bioterrorism. These new regulations will lead to increased scrutiny of the use of select biological agents in registered research laboratories, but the regulations may have unintended effects on cost, progress, and perceptions in programs previously considered part of the academic research community. We review the history of biosurety, evolving guidelines, implementation of the regulations, and impacts at the lead research laboratory for medical biological defense for the Department of Defense.

Viral replication and host gene expression in alveolar macrophages infected with Ebola virus (Zaire strain).

In order to characterize the cellular response to and identify potential diagnostic markers for the early detection of Ebola virus, an in vitro culture system involving nonhuman primate alveolar macrophages was developed. Ebola virus replication in the alveolar macrophages was characterized by plaque assay, immunohistochemical analysis, and in situ hybridization. Fluorogenic 5'-nuclease assays specific for nonhuman primate proinflammatory cytokines and chemokines were designed and used to evaluate mRNA transcription in macrophages infected with Ebola virus. Transient increases in cytokine and chemokine mRNA levels were observed immediately following exposure to Ebola virus. At 2 h postexposure, levels of cytokine and chemokine mRNAs were markedly reduced. Although Ebola virus infection of alveolar macrophages failed to induce a sustained increase in proinflammatory cytokine and chemokine mRNA transcription (potentially reducing the use of these markers as diagnostic tools), the fluorogenic 5'-nuclease assays developed may have prognostic value for individuals infected with Ebola virus. Recently published data have indicated that persons who remain asymptomatic after exposure to Ebola virus are capable of mounting an early proinflammatory cytokine response and that those who become clinically ill are not. If implemented immediately after exposure, these assays could be used to predict which individuals will be more likely to remain asymptomatic as opposed to those who will be more likely to develop clinical signs and eventually succumb to the virus.