Effect of environmental factors on aerosol‐induced lassa virus infection

Abstract

Previous studies suggested that the most frequent means of transmission of Lassa virus was by either direct or indirect contact with infectious material. Aerosol stability and respiratory infectivity of the Josiah strain of Lassa virus were assessed to determine the effect of environmental factors on aerosol-induced infection. The stability of the virus in aerosol, particularly at low relative humidity (30% RH), plus the ability of the virus to infect guinea pigs and monkeys via the respiratory route emphasize the potential for aerosol transmission of Lassa virus. Biological half-lives at both 24 and 32 degrees C ranged from 10.1 to 54.6 min, and were sufficient for aerosol dispersion of virus to considerable distances in natural situations. Infectivity of Lassa virus in small particle aerosol was demonstrated in outbred guinea pigs and cynomolgus monkeys using dynamic aerosol equipment. Monkeys exposed to inhaled doses to 465 PFU were infected and died. The median infectious dose (ID50) for guinea pigs was 15 PFU, yet a definitive median lethal aerosol dose (LD50) could not be established. Organ tropism of aerosol-induced Lassa virus infections in outbred guinea pigs was similar to that previously reported for inbred guinea pigs infected by subcutaneous inoculation.

Hemorrhagic fever occurs after intravenous, but not after intragastric, inoculation of rhesus macaques with lymphocytic choriomeningitis virus

“…However, epidemiological and laboratory studies implicate mucosal routes of infection as the most common natural mode of transmission [Danes et al, 1963;Stephensen et al, 1984;ter Meulen et al, 1996;Rai et al, 1997]. Our work in the murine model of LCMV indicates that intragastric infection is less efficient than intravenous infection .…”

Early and Strong Immune Responses Are Associated with Control of Viral Replication and Recovery in Lassa Virus-Infected Cynomolgus Monkeys

“…Here, we report some virological, pathological, and immunological variables associated with fatal and nonfatal outcomes after LV infection of cynomolgus monkeys. Both rhesus monkeys (7,26,33,65) and cynomolgus monkeys have frequently been used as models for Lassa fever, and similar clinical signs and pathological events have been observed after LV infection in these closely related species (16,21,27,29,58). We used two different doses of virus to assess the influence of the viral inoculum on the disease course, and because the AV strain of LV has never been evaluated in primate models.…”

“…Therefore, nonhuman primates are still the only relevant model for Lassa fever: rhesus and cynomolgus monkeys (Macaca mulatta and Macaca fascicularis, respectively) are the primates that have been most extensively used (7,16,21,26,27,29,58,65). These closely related nonhuman primates both reproduce the systemic disease involving most of the visceral organs, with microscopic lesions, including hepatocellular necrosis, interstitial pneumonia, arteritis, and encephalitis.…”

Managing Potential Laboratory Exposure to Ebola Virus by Using a Patient Biocontainment Care Unit1

“…It is acknowledged that BSL-4-like infection control precautions may not be necessary for observation or illness. However, most clinical experience managing fi lovirus infections is from sub-Saharan Africa, where increased temperature and humidity may reduce stability of viruses in aerosol (22). Contrast that environment with a US hospital where air is cool, dry, and recycled within the facility, a setting potentially more conducive to airborne virus spread.…”