A low-passage insect-cell isolate of bluetongue virus uses a macropinocytosis-like entry pathway to infect natural target cells derived from the bovine host

Abstract

Bluetongue virus (BTV) causes an economically important disease in domestic and wildlife ruminants and is transmitted by Culicoides biting midges. In ruminants, BTV has a wide cell tropism that includes endothelial cells of vascular and lymphatic vessels as important cell targets for virus replication, and several cell types of the immune system including monocytes, macrophages and dendritic cells. Thus, cell-entry represents a particular challenge for BTV as it infects many different cell types in widely diverse vertebrate and invertebrate hosts. Improved understanding of BTV cell-entry could lead to novel antiviral approaches that can block virus transmission from cell to cell between its invertebrate and vertebrate hosts. Here, we have investigated BTV cell-entry using endothelial cells derived from the natural bovine host (BFA cells) and purified whole virus particles of a low-passage, insect-cell isolate of a virulent strain of BTV-1. Our results show that the main entry pathway for infection of BFA cells is dependent on actin and dynamin, and shares certain characteristics with macropinocytosis. The ability to use a macropinocytosis-like entry route could explain the diverse cell tropism of BTV and contribute to the efficiency of transmission between vertebrate and invertebrate hosts.

African Horse Sickness: A Review of Current Understanding and Vaccine Development

“…First, the antigenic tip domains bind to certain surface cell receptors which have yet to be identified. There is some preliminary evidence implicating heparin sulphate as one possible candidate [59], but due to the high sequence variability in the AHSV outer protein VP2, it is possible that different receptors and entry mechanisms may be utilized by the different serotypes to enter distinct cell types [60]. These initial bonds are then stabilised by a second connection between the SA-binding domain and a surface glycoprotein such as glycophorin A [61,62], which is a heavily glycosylated sialoglycoprotein abundantly present on the surface of equine erythrocytes.…”

“…These initial studies suggested that viral cell entry was accomplished by clathrin-mediated endocytosis. However, more recently evidence has been presented which describes a macropinocytosis-like entry route dependant on actin and dynamin [60]. In both instances, the low pH (6.0–6.5) within the early endosome disturbs the interactions between VP2 and VP7, facilitating detachment of the VP2 trimers and disrupting the zinc finger motif situated at the interface between the VP2 hub and body domains, which is believed to play a role in controlling conformational changes [30].…”

Review on the Biology of African Horse Sickness Virus and Its Vector

“…For attachment antigenic tip domains bind to certain surface sulphate as one possible candidate [54], but due to the high sequence variability in the AHSV outer cell receptors which have yet to be identified. Different receptors and entry mechanisms used by different serotypes to enter different cell types [76]. However, bond was stabilized by inter linkage between surface glycoprotein (glycophorin A) and SA-binding domain which is a heavily glycosylated sialoglycoprotein abundantly exist on the surface of equine erythrocytes [20].…”

Bovine Organospecific Microvascular Endothelial Cell Lines as New and Relevant In Vitro Models to Study Viral Infections

“…Endothelial cells are often targeted by viruses, including members of Flaviviridae such as dengue, West Nile or Zika viruses [ 7 ], or members of Reoviridae such as African horse sickness virus or Bluetongue (BT) virus (BTV) [ 8 ], which can result in severe lesions. For instance, Bluetongue is transmitted by hematophagous Culicoides midges and is notably characterized in domestic ruminants by vascular injury with hemorrhage and ulceration of the oral cavity and upper gastrointestinal tract, tissue infarction, and widespread edema [ 9 ].…”

“…For instance, Bluetongue is transmitted by hematophagous Culicoides midges and is notably characterized in domestic ruminants by vascular injury with hemorrhage and ulceration of the oral cavity and upper gastrointestinal tract, tissue infarction, and widespread edema [ 9 ]. Endothelial cells represent the major site of BTV replication, thus explaining the typical lesions that result in excessive bleeding and coagulopathy [ 8 , 10 ]. In the case of Dengue, hemorrhagic fever and shock syndrome are caused by vascular leakage due to impaired endothelial permeability [ 11 ].…”