Ebola Reston Virus Infection of Pigs: Clinical Significance and Transmission Potential

Abstract

In 2008, Reston ebolavirus (REBOV) was isolated from pigs during a disease investigation in the Philippines. Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV-2) infections were also confirmed in affected herds and the contribution of REBOV to the disease outbreak remains uncertain. We have conducted experimental challenge studies in 5-week-old pigs, with exposure of animals to 10(6) TCID(50) of a 2008 swine isolate of REBOV via either the oronasal or subcutaneous route. Replication of virus in internal organs and viral shedding from the nasopharynx were documented in the absence of clinical signs of disease in infected pigs. These observations confirm not only that asymptomatic infection of pigs with REBOV occurs, but that animals so affected pose a transmission risk to farm, veterinary, and abattoir workers.

Index of Authors

“…Almost no infiltration of other immune cells into the lungs was observed for macaques infected with ZEBOV [12] or pigs infected with REBOV [10], while massive infiltration of not only macrophages but also neutrophils and lymphocytes was observed in the lungs of older piglets infected with ZEBOV, although antigen was present only in the alveolar macrophages. The infiltration had essentially reached the point when no alveolar space was left, and lead to necrosis 5-7 days post-infection [11].…”

“…Shedding from the nasopharynx at the RNA and infectious virus levels was detected in all pigs inoculated oronasally. The virus was detected in multiple organs in all inoculated pigs, although the piglets remained clinically healthy [10].…”

“…REBOV RNA was also detected in skeletal muscle, but the RNA detection attempts in the muscle of ZEBOV infected piglets were negative [10,11].…”

“…Marsh and co-authors infected oronasally eight 5-6 weeks old piglets with 10 6 TCID 50 of the Philippines 2008 isolate of REBOV, and eight piglets of the same age subcutaneously with the same dose of virus [10]. Shedding from the nasopharynx at the RNA and infectious virus levels was detected in all pigs inoculated oronasally.…”

“…IgG antibody development was detected using ELISA in subcutaneously inoculated piglets at 8 dpi, when only 2 out of 4 oronasally infected pigs seroconverted. All pigs were considered positive for EBOV IgG antibody at 10 dpi [10], similar to the antibody development against ZEBOV.…”