Lumpy Skin Disease Is Characterized by Severe Multifocal Dermatitis With Necrotizing Fibrinoid Vasculitis Following Experimental Infection

Abstract

Lumpy skin disease is a high-consequence disease in cattle caused by infection with the poxvirus lumpy skin disease virus (LSDV). The virus is endemic in most countries in Africa and an emerging threat to cattle populations in Europe and Asia. As LSDV spreads into new regions, it is important that signs of disease are recognized promptly by animal caregivers. This study describes the gross, microscopic, and ultrastructural changes that occur over time in cattle experimentally challenged with LSDV. Four calves were inoculated with wildtype LSDV and monitored for 19 to 21 days. At 7 days after inoculation, 2 of the 4 cattle developed multifocal cutaneous nodules characteristic of LSD. Some lesions displayed a targetoid appearance. Histologically, intercellular and intracellular edema was present in the epidermis of some nodules. Occasional intracytoplasmic inclusion bodies were identified in keratinocytes. More severe and consistent changes were present in the dermis, with marked histiocytic inflammation and necrotizing fibrinoid vasculitis of dermal vessels, particularly the deep dermal plexus. Chronic lesions consisted of full-thickness necrosis of the dermis and epidermis. Lesions in other body organs were not a major feature of LSD in this study, highlighting the strong cutaneous tropism of this virus. Immunohistochemistry and electron microscopy identified LSDV-infected histiocytes and fibroblasts in the skin nodules of affected cattle. This study highlights the noteworthy lesions of LSDV and how they develop over time.

Madin-Darby bovine kidney (MDBK) cells are a suitable cell line for the propagation and study of the bovine poxvirus lumpy skin disease virus

“…In order to develop a PRNT for LSDV, sera from five calves experimentally inoculated with LSDV were analysed. The experimental study has been described previously ( Sanz-Bernardo et al, 2020 ). Briefly, one calf (#1) was not inoculated and served as a negative control.…”

“…The polyclonal anti-LSDV074 antibody was a kind gift from IDvet (France). The sera used in the neutralization assays were collected from five calves at 21 days post-challenge with LSDV ( Sanz-Bernardo et al, 2020 ).…”

Quantifying and modelling the acquisition and retention of lumpy skin disease virus by haematophagus insects reveals clinically but not subclinically-affected cattle are promoters of viral transmission and key targets for control of disease outbreaks

“…act as donors on which blood-feeding insects could feed. The clinical and pathological findings (summarised in Text S1) have been described previously 9 , and resemble those of naturally infected cattle 2,4,8,11,12,37 . Three calves (calves 3, 5, and 9) developed lumpy skin disease, characterised by severe multifocal dermatitis with necrotising fibrinoid vasculitis consistent with field reports of LSD ( Figure S1).…”

“…Cattle were housed in the primary high containment animal facilities (Biosafety Level 3 Agriculture) at The Pirbright Institute. The husbandry of the animals during the study was described previously 9 .…”

“…LSDV is a rapidly emerging pathogen. LSD is characterised by fever, weight loss, and prominent multifocal necrotising cutaneous lesions 9 , and affect cattle of all ages 10 . Morbidity in disease outbreaks range from 5-26%, and mortality 0.03-2% [2][3][4][11][12][13] .…”