Intrapancreatic accessory spleens in African swine fever infection of wild boar (Sus scrofa)

Néstor Porras; Blanca Chinchilla; Antonio Rodríguez-Bertos; José Á Barasona; Aleksandra Kosowska; Esther Vázquez-Fernández; Pedro J Sánchez-Cordón; José M Sánchez-Vizcaíno

doi:10.3389/fvets.2023.1306320

Intrapancreatic accessory spleens in African swine fever infection of wild boar (Sus scrofa)

Front Vet Sci. 2023 Dec 12:10:1306320. doi: 10.3389/fvets.2023.1306320. eCollection 2023.

Authors

Affiliations

¹ VISAVET Health Surveillance Centre, Complutense University of Madrid, Madrid, Spain.
² Department of Animal Production, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain.
³ Department of Internal Medicine and Animal Surgery, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain.
⁴ Department of Animal Health, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain.
⁵ Pathology Department, Animal Health Research Center (CISA), National Institute of Research, Agricultural and Food Technology (INIA-CSIC), Madrid, Spain.

Abstract

Intrapancreatic accessory spleen (IPAS) is one of the most frequent congenital splenic anomalies in humans; however, studies in veterinary medicine are scarce. This study aimed to describe the macroscopic, histopathological and immunohistochemical features of 11 suspected cases of IPAS in wild boar piglets of 3-4 months old. Seven of the 11 animals were immunised with a low virulence isolate of African swine fever virus (ASFV) and subsequently challenged with a highly virulent ASFV isolate (LVI-HVI group). The remaining four animals were exclusively infected with a highly virulent isolate of ASFV (HVI group). Grossly, lesions comprised focal or multifocal reddish areas of variable shape, located on the surface of the pancreatic tail or within the parenchyma. Histological and immunohistochemical studies (anti-CD79 and CD3) confirmed the presence of IPAS in eight of the 11 cases. IPAS shared the same histological structure and alterations as those observed in the original spleen. The immunohistochemical study against ASFV revealed the presence of VP72+ cells in both the spleen and IPAS of seven of the eight piglets. The results of this study describe for the first time the presence of IPAS in ASFV infection of wild boar (Sus scrofa) regardless the isolate and suggest that the infection may induce the development of ectopic splenic tissue due to an increased demand for phagocytic cells from the reticuloendothelial system. However, further studies are needed to understand the immunological mechanisms that trigger the formation of these accessory organs.

Keywords: African swine fever virus (ASFV); highly virulent isolate; histopathology; immunohistochemistry; intrapancreatic accessory spleen (IPAS); low virulence isolate; wild boar.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was funded by European Project H2020 VACDIVA – “A Safe DIVA vaccine for African Swine Fever control and eradication,” grant agreement n° 862874.