Clinical Course and Gross Pathological Findings in Wild Boar Infected with a Highly Virulent Strain of African Swine Fever Virus Genotype II

Abstract

African swine fever (ASF) is a notifiable disease that in recent years has spread remarkably in Europe and Asia. Eurasian wild boar (Sus scrofa) plays a key role in the maintenance and spread of the pathogen. Here we examined gross pathology of infection in wild boar with a highly virulent, hemadsorbing genotype II ASF virus (ASFV) strain. To this end, six wild boars were intramuscularly inoculated with the 10 HAD50 Arm07 ASFV strain, and 11 wild boars were allowed to come into direct contact with the inoculated animals. No animals survived the infection. Clinical course, gross pathological findings and viral genome quantification by PCR in tissues did not differ between intramuscularly inoculated or contact-infected animals. Postmortem analysis showed enlargement of liver and spleen; serosanguinous effusion in body cavities; and multiple hemorrhages in lungs, endocardium, brain, kidneys, urinary bladder, pancreas, and alimentary system. These results provide detailed insights into the gross pathology of wild boar infected with a highly virulent genotype II ASFV strain. From a didactic point of view, this detailed clinical course and macroscopic description may be essential for early postmortem detection of outbreaks in wild boar in the field and contribute to disease surveillance and prevention efforts.

The Role of Interleukine-10 and Interferon-γ as Potential Markers of the Evolution of African Swine Fever Virus Infection in Wild Boar

“…The combination of a strong humoral response and high levels of IFN-γ might have protected the vaccinated animals from the virulent isolate. These results coincide with those of previous studies, in which elevated IFN-γ levels have been associated with specific immune responses [14,47,48]. For instance, it has been reported that the deletion of IFN-γ inhibitor genes DP148R, MGF360, and 530/505 genes from ASFV Benin97/1 isolate induced protective immune responses against a challenge [35], thus showing the importance of this cytokine in regards to triggering an effective immune response against the virus.…”

Distinct African Swine Fever Virus Shedding in Wild Boar Infected with Virulent and Attenuated Isolates

“…Some animals had slight erythema, ocular and nasal discharges, slight walking difficulties, and an increased respiratory rate. These observations were previously detailed by Rodríguez-Bertos et al [ 22 ].…”

“…Because of the lack of differences with regard to clinical course, pathological findings, and virus presence in tissues ( Supplementary Table S1 ) between the intramuscularly inoculated or in-contact animals, we considered the six wild boars intramuscularly inoculated and the 11 in-contact wild boars in a single group, denominated as the virulent group. Their study period lasted 15 days, as described previously by Rodríguez-Bertos et al [ 22 ] ( Figure 1 ).…”

“…The hemadsorbing p72 genotype II ASFV Armenia07 isolate was used as the field virulent virus. This isolate was previously described as a highly virulent ASFV in wild boar, causing an acute rapid progression of the disease [ 22 ]. The virus was propagated in PBM as described in [ 24 ].…”

“…This paper examines the shedding patterns of the attenuated ASFV isolate Lv17/WB/Riel in order to evaluate its potential as a vaccine candidate for wild boar. The possible survival and shedding of AFSV were investigated by collecting blood, oral swabs, and feces while carrying out previously published studies in which wild boars were orally inoculated with the Lv17/WB/Rie1 ASFV isolate [ 5 ] and another study where wild boars were intramuscularly inoculated with the highly virulent Arm07 ASFV isolate [ 22 ]. This information will help to determine the potential risk of the deliberate release into the environment of this attenuated isolate in comparison with highly virulent field isolates and will additionally complement studies previously described by Barasona et al [ 5 ] and Rodríguez-Bertos et al [ 22 ].…”