Open Access
Vet. Res.
Volume 37, Number 1, January-February 2006
Page(s) 15 - 23
Published online 13 December 2005
How to cite this article Vet. Res. (2006) 15-23
Vet. Res. 37 (2006) 15-23
DOI: 10.1051/vetres:2005041

Pathogenesis of encephalomyocarditis experimental infection in young piglets: a potential animal model to study viral myocarditis

Daniela Gelmettia, Alessandra Meronia, Emiliana Brocchia, Frank Koenenb and Giorgio Cammaratac

a  Istituto Zooprofilattico Sperimentale Lombardia-Emilia Romagna,Via Celoria 12, 20133 Milano, Italy
b  Veterinary and Agrochemical Research Centre (CODA), Groeselenberg 99, 1180 Ukkel, Belgium
c  Dipartimento di patologia animale, igiene, profilassi e sanità pubblica veterinaria, Università degli Sudi di Milano, Via Celoria 10, 20133 Milano, Italy

(Received 13 August 2004; accepted 9 June 2005; published online 13 December 2005)

Abstract - The pathogenesis of encephalomyocarditis (EMC) due to the EMC virus (EMCV) was studied in 24 piglets oro-nasally infected with the field isolate B279/95. Two pigs were kept as negative controls and were euthanised at hour 0. The remaining 24 were euthanised every 6 h up to 78-h post infection (hpi). Virus isolation, histological examination and EMCV immunodetection were performed on the spleen, intestine, pancreas, liver, kidneys, heart, lungs, lymph nodes, tonsils and brain. EMCV was isolated at 6-hpi from the intestine and lymph nodes and at 12-hpi from the heart. From 6 to 12-hpi, scattered degenerate myocardiocytes were immunolabelled. Subsequently, myocarditis developed and progressively worsened. Immunopositive reaction in tonsil macrophages, observed in the early stage of infection (6-hpi), suggests that tonsils are the portal of entry, and by mean of wandering macrophages the EMC virus is then distributed through the body. Afterwards, EMCV-B279/95 replicates intensively in the cytoplasm of myocardiocytes and the acute myocarditis is strictly related to the tropism of these cells. Four pigs died spontaneously. In three animals no post mortem lesions or virus were isolated/detected, although all of them showed mild myocarditis. The experimental infection with EMCV B279/95 indicates: (i) the experimental protocol mimics the individual variability observed in natural disease, (ii) tonsils are the portal of entry of infection and the heart is the target organ, (iii) EMCV provides a valuable animal model for comparative studies on progressive viral myocarditis.

Key words: encephalomyocarditis virus-EMCV / swine / myocarditis / immunohistochemistry

Corresponding author: Daniela Gelmetti

© INRA, EDP Sciences 2005