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Research article - Peer-reviewed, 2021

Evaluation of Lesions and Viral Antigen Distribution in Domestic Pigs Inoculated Intranasally with African Swine Fever Virus Ken05/Tk1 (Genotype X)

Sanchez-Cordon, Pedro J.; Floyd, Tobias; Hicks, Daniel; Crooke, Helen R.; McCleary, Stephen; McCarthy, Ronan R.; Strong, Rebecca; Dixon, Linda K.; Neimanis, Aleksija; Wikstrom-Lassa, Emil; Gavier-Widen, Dolores; Nunez, Alejandro


The understanding of the pathogenic mechanisms and the clinicopathological forms caused by currently circulating African swine fever virus (ASFV) isolates is incomplete. So far, most of the studies have been focused on isolates classified within genotypes I and II, the only genotypes that have circulated outside of Africa. However, less is known about the clinical presentations and lesions induced by isolates belonging to the other twenty-two genotypes. Therefore, the early clinicopathological identification of disease outbreaks caused by isolates belonging to, as yet, not well-characterised ASFV genotypes may be compromised, which might cause a delay in the implementation of control measures to halt the virus spread. To improve the pathological characterisation of disease caused by diverse isolates, we have refined the macroscopic and histopathological evaluation protocols to standardise the scoring of lesions. Domestic pigs were inoculated intranasally with different doses (high, medium and low) of ASFV isolate Ken05/Tk1 (genotype X). To complement previous studies, the distribution and severity of macroscopic and histopathological lesions, along with the amount and distribution of viral antigen in tissues, were characterised by applying the new scoring protocols. The intranasal inoculation of domestic pigs with high doses of the Ken05/Tk1 isolate induced acute forms of ASF in most of the animals. Inoculation with medium doses mainly induced acute forms of disease. A less severe but longer clinical course, typical of subacute forms, characterised by the presence of more widespread and severe haemorrhages and oedema, was observed in one pig inoculated with the medium dose. The severity of vascular lesions (haemorrhages and oedema) induced by high and medium doses was not associated with the amount of virus antigen detected in tissues, therefore these might be attributed to indirect mechanisms not evaluated in the present study. The absence of clinical signs, lesions and detectable levels of virus genome or antigen in blood from the animals inoculated with the lowest dose ruled out the existence of possible asymptomatic carriers or persistently infected pigs, at least for the 21 days period of the study. The results corroborate the moderate virulence of the Ken05/Tk1 isolate, as well as its capacity to induce both the acute and, occasionally, subacute forms of ASF when high and medium doses were administered intranasally.


African swine fever virus; genotype X; domestic pig; Sus scrofa domesticus; infection routes and doses; pathology; lesion scoring; viral antigen distribution in tissues

Published in

2021, volume: 10, number: 6, article number: 768
Publisher: MDPI

Authors' information

Sanchez-Cordon, Pedro J.
Instituto Nacional Investigacion Tecnologia Agraria Alimentaria (INIA)
Floyd, Tobias
Animal & Plant Health Agency
Hicks, Daniel
Animal & Plant Health Agency
Crooke, Helen R.
Animal & Plant Health Agency
McCleary, Stephen
Animal & Plant Health Agency
McCarthy, Ronan R.
Animal & Plant Health Agency
Strong, Rebecca
Animal & Plant Health Agency
Dixon, Linda K.
The Pirbright Institute
Neimanis, Aleksija
National Veterinary Institute SVA
Wikström-Lassa, Emil
National Veterinary Institute (SVA)
Gavier-Widen, Dolores (Gavier Widén, Dolores)
National Veterinary Institute (SVA)
Gavier-Widen, Dolores (Gavier Widén, Dolores)
Swedish University of Agricultural Sciences, Department of Biomedical Science and Veterinary Public Health
Núñez, Alejandro
Animal & Plant Health Agency

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