Immunohistochemical identification of a malignant catarrhal fever virus in cattle with renal diseases from Paraná state, Southern Brazil: A retrospective epidemiological study

Authors: XAVIER, ANA - State University Of Londrina; QUEIROZ, GUSTAVO - Universidade Federal Do Parana; LISBÔA, JÚLIO - State University Of Londrina; Cunha, Cristina; HEADLEY, SELWYN - State University Of Londrina

Submitted to: Tropical Animal Health and Production
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2023
Publication Date: 10/2/2023
Citation: Xavier, A.A., Queiroz, G.R., Lisbôa, J.A., Cunha, C.W., Headley, S.A. 2023. Immunohistochemical identification of a malignant catarrhal fever virus in cattle with renal diseases from Paraná state, Southern Brazil: A retrospective epidemiological study. Tropical Animal Health and Production. 55. Article 344. https://doi.org/10.1007/s11250-023-03740-y.
DOI: https://doi.org/10.1007/s11250-023-03740-y

Interpretive Summary: Malignant catarrhal fever (MCF) is a severe and fatal syndrome that affects mainly ruminants caused by a group of herpes viruses collectively identified as MCF viruses (MCFV). The goal of this study was to determine the prevalence of MCFV infections in cattle within the state of Paraná, Brazil, and to better understand renal pathologies associated with the infection. Kidney samples from cattle with renal disease submitted to the Laboratory of Animal Pathology, Universidade Estadual de Londrina, Paraná, Brazil during the period of January 2010 and December 2019 were used in the study. The samples were examined for pathological manifestations and evaluated for the presence of MCFV-specific antigens using immunohistochemistry. Out of 115 samples examined, 48 (41.7%) showed positive reactivity for MCFV antigens. The principal histological findings in MCFV infected animals were lymphocytic interstitial nephritis and proliferative vascular lesions. Presence of MCFV antigens in kidneys was not associated with age, gender or breed of animals or with their geographic localization or season. The study confirms that MCFV infections are endemic in the state of Paraná and suggests that kidney can be a valuable tissue to be submitted to laboratory testing for definitive diagnosis of MCF in cattle.

Technical Abstract: Sheep associated-malignant catarrhal fever (SA-MCF) is a viral infectious disease caused by gamma herpesviruses within the MCF virus (MCFV) complex group. This study determined the prevalence of MCFV-associated infections in cattle within the mesoregions of the state of Paraná, Southern Brazil, by analyzing the histopathologic patterns of renal lesions in association with positive immunoreactivity to intralesional antigens of MCFV. Intracytoplasmic MCFV antigens were identified in 41.7% (48/115) of the kidneys evaluated. The median morbidity, mortality and lethality rates were 4.2%, 3%, and 100%, respectively; most infections were identified in cattle from the North Central mesoregion. Significant differences in breeds, gender, and seasonal predominance were not identified; however, calves 12 months of age or younger were more frequently affected. Lymphocytic interstitial nephritis, vascular degeneration, and ballooning degeneration of the renal tubules were the principal histopathological findings associated with positive immunoreactivity to MCFV. The results indicate that MCFV infections are endemic within state of Paraná and suggest that kidney can be of diagnostic value in suspected cases of MCF in cattle. Furthermore, the utilization of in situ diagnosis resulted in the detection of a greater number of cases of infections by MCFV than previously determined using other methods. Additionally, degenerative vascular lesions of the kidney should be considered during the establishment of a histological diagnosis of MCFV-induced infections in cattle in the absence of fibrinoid change or necrotizing vasculitis.