Civets are equally susceptible to experimental infection by two different severe acute respiratory syndrome coronavirus isolates

Abstract

Severe acute respiratory syndrome (SARS) was caused by a novel virus now known as SARS coronavirus (SARS-CoV). The discovery of SARS-CoV-like viruses in masked palm civets (Paguma larvata) raises the possibility that civets play a role in SARS-CoV transmission. To test the susceptibility of civets to experimental infection by different SARS-CoV isolates, 10 civets were inoculated with two human isolates of SARS-CoV, BJ01 (with a 29-nucleotide deletion) and GZ01 (without the 29-nucleotide deletion). All inoculated animals displayed clinical symptoms, such as fever, lethargy, and loss of aggressiveness, and the infection was confirmed by virus isolation, detection of viral genomic RNA, and serum-neutralizing antibodies. Our data show that civets were equally susceptible to SARS-CoV isolates GZ01 and BJ01.

FIG. 1.

Clinical changes in civets after inoculation with SARS coronavirus (SARS-CoV). (A) Daily average temperature of animals in groups A and B plotted together with the daily temperature of the control animal. Febrile episodes commenced around 3 dpi, and temperatures remained elevated for up to 7 days in infected civets. (B) White blood cell (WBC) counts measured on day 0 and at 3, 8, and 13 dpi for the control animal and animals in groups A and B. For animals in groups A and B, the average counts are used in the plot. Leucopenia was observed, with white blood cell counts reaching a minimum at approximately 3 dpi and recovering to about normal levels from 13 dpi.

FIG. 2.

Pathological changes in civets after inoculation with SARS-CoV. Lung tissues were taken at 13 dpi from animal no. 5 of group A (A) and no. 7 of group B (B). Alveolar septa enlargement with macrophage and lymphocyte infiltration was evident in both animals. (C) Hematoxylin and eosin stain (magnification, ×20) of lung tissue of the control animal showed no abnormal changes.

FIG. 2.

Pathological changes in civets after inoculation with SARS-CoV. Lung tissues were taken at 13 dpi from animal no. 5 of group A (A) and no. 7 of group B (B). Alveolar septa enlargement with macrophage and lymphocyte infiltration was evident in both animals. (C) Hematoxylin and eosin stain (magnification, ×20) of lung tissue of the control animal showed no abnormal changes.

FIG. 2.

Pathological changes in civets after inoculation with SARS-CoV. Lung tissues were taken at 13 dpi from animal no. 5 of group A (A) and no. 7 of group B (B). Alveolar septa enlargement with macrophage and lymphocyte infiltration was evident in both animals. (C) Hematoxylin and eosin stain (magnification, ×20) of lung tissue of the control animal showed no abnormal changes.