Preclinical coronavirus studies and pathology: Challenges of the high-containment laboratory

Abstract

The COVID-19 pandemic has highlighted the critical role that animal models play in elucidating the pathogenesis of emerging diseases and rapidly analyzing potential medical countermeasures. Relevant pathologic outcomes are paramount in evaluating preclinical models and therapeutic outcomes and require careful advance planning. While there are numerous guidelines for attaining high-quality pathology specimens in routine animal studies, preclinical studies using coronaviruses are often conducted under biosafety level-3 (BSL3) conditions, which pose unique challenges and technical limitations. In such settings, rather than foregoing pathologic outcomes because of the inherent constraints of high-containment laboratory protocols, modifications can be made to conventional best practices of specimen collection. Particularly for those unfamiliar with working in a high-containment laboratory, the authors describe the logistics of conducting such work, focusing on animal experiments in BSL3 conditions. To promote scientific rigor and reproducibility and maximize the value of animal use, the authors provide specific points to be considered before, during, and following a high-containment animal study. The authors provide procedural modifications for attaining good quality pathologic assessment of the mouse lung, central nervous system, and blood specimens under high-containment conditions while being conscientious to maximize animal use for other concurrent assays.

Keywords: BSL3; SARS-CoV-2; biosafety; coronavirus; high-containment; preclinical model; specimen handling.

Figure 1.

Typical personal protective equipment worn in a BSL3 facility, including powered air-purifying respirator, Tyvek suit, solid-front gown, double gloves, and shoe covers.

Figure 2.

Conducting animal studies in a biosafety cabinet in a BSL3 facility.

Figures 3–6.

Examples of standard hands-on versus preferred hands-free techniques when using sharps with animals in a BSL3 facility. Figure 3. Cardiocentesis was performed with the nondominant hand stabilizing the mouse body. Figure 4. Cardiocentesis was performed with forceps stabilizing the mouse body. Figure 5. Intracranial inoculation was performed with the nondominant hand stabilizing the mouse head. Figure 6. Intracranial inoculation was performed with forceps stabilizing the mouse head.

Figures 7–8.

Direct lung lobe inflation, mouse. Figure 7. Clamping of the main bronchus with hemostats. Figure 8. Instillation of fixative into lung parenchyma with a 29G needle on an insulin syringe.

Figures 9–10.

Lung, mouse. Hematoxylin and eosin. Figure 9. A needle track artifact is visible. The left lung lobe was directly injected with formalin using an insulin syringe with a 30G needle. Figure 10. Typical histomorphology with inflation of alveoli acceptable for pathologic assessment. The lung was inflated by direct injection of air as shown in Figs. 7, 8.