Bovine Lactoferrin Inhibits Dengue Virus Infectivity by Interacting with Heparan Sulfate, Low-Density Lipoprotein Receptor, and DC-SIGN.

Jo-Mei Chen,Jen-Wei Lin,Yi-Chin Fan,Wei-Li Hsu,Shyan-Song Chiou,Yi-Ying Chen

doi:10.3390/ijms18091957

Abstract

Bovine lactoferrin (bLF) presents in milk and has been shown to inhibit several viral infections. Effective drugs are unavailable for the treatment of dengue virus (DENV) infection. In this study, we evaluated the antiviral effect of bLF against DENV infection in vivo and in vitro. Bovine LF significantly inhibited the infection of the four serotypes of DENV in Vero cells. In the time-of-drug addition test, DENV-2 infection was remarkably inhibited when bLF was added during or prior to the occurrence of virus attachment. We also revealed that bovine LF blocks binding between DENV-2 and the cellular membrane by interacting with heparan sulfate (HS), dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN), and low-density lipoprotein receptors (LDLR). In addition, bLF inhibits DENV-2 infection and decreases morbidity in a suckling mouse challenge model. This study supports the finding that bLF may inhibit DENV infection by binding to the potential DENV receptors.

Highlights

Lactoferrin (LF) is an iron-binding glycoprotein of 692 amino acids in length, and is present in breast milk and mucous secretions [1]
In order to study the anti-dengue virus (DENV) activity of Bovine lactoferrin (bLF), Vero cell monolayers were infected with DENV-1 to -4 at a multiplicity of infection (MOI) of five for 24 h with or without bLF (200 μg/mL), and analyzed by indirect immunofluorescence assay (IFA) to determine infection rates (File S1)
In the presence of bLF, the infection rates of DENV-1 to -4 decreased by 43%, 76%, 61% and 56%, respectively, relative to rates observed in the absence of bLF

Summary

Introduction

Lactoferrin (LF) is an iron-binding glycoprotein of 692 amino acids in length, and is present in breast milk and mucous secretions [1]. LF is a multifunctional protein that is involved in iron transportation in the intestines and blood, the inhibition of viral and bacterial infections, the modulation of immunity, and nonspecific immune responses [1,2]. The excellent antiviral activity of LF has been shown to prevent several viral infections, ones caused by intestinally and mucosally-transmitted viruses, by binding to viral particles or viral receptors on the host cell membrane [3,4]. Positively-charged LF can interact with negatively-charged compounds such as glycosaminoglycan (GAG), inhibiting virus-receptor interaction [5]. In addition to interacting with GAGs, LF prevents viral infections by binding to dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) and low-density lipoprotein receptors (LDLR) [6,7]. DENV is an encapsidated and enveloped virus consisting of genome of 11 kb positive-sense, single-stranded RNA that encodes 10 viral proteins, including a capsid, a premembrane/membrane, and an envelope (E) protein; and seven nonstructural proteins, designated NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5 [9]

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Conclusion