Toll-like receptor 4-mediated activation of p38 mitogen-activated protein kinase is a determinant of respiratory virus entry and tropism.
Respiratory viruses exert a heavy toll of morbidity and mortality worldwide. Despite this burden there are few specific treatments available for respiratory virus infections. Since many viruses utilize host cell enzymatic machinery such as protein kinases for replication, we determined whether pharmacological inhibition of kinases could, in principle, be used as a broad antiviral strategy for common human respiratory virus infections. A panel of green fluorescent protein (GFP)-expressing recombinant respiratory viruses, including an isolate of H1N1 influenza virus (H1N1/Weiss/43), was used to represent a broad range of virus families responsible for common respiratory infections (Adenoviridae, Paramyxoviridae, Picornaviridae, and Orthomyxoviridae). Kinase inhibitors were screened in a high-throughput assay that detected virus infection in human airway epithelial cells (1HAEo-) using a fluorescent plate reader. Inhibition of p38 mitogen-activated protein kinase (MAPK) signaling was able to significantly inhibit replication by all viruses tested. Therefore, the pathways involved in virus-mediated p38 and extracellular signal-regulated kinase (ERK) MAPK activation were investigated using bronchial epithelial cells and primary fibroblasts derived from MyD88 knockout mouse lungs. Influenza virus, which activated p38 MAPK to approximately 10-fold-greater levels than did respiratory syncytial virus (RSV) in 1HAEo- cells, was internalized about 8-fold faster and more completely than RSV. We show for the first time that p38 MAPK is a determinant of virus infection that is dependent upon MyD88 expression and Toll-like receptor 4 (TLR4) ligation. Imaging of virus-TLR4 interactions showed significant clustering of TLR4 at the site of virus-cell interaction, triggering phosphorylation of downstream targets of p38 MAPK, suggesting the need for a signaling receptor to activate virus internalization.
Marchant
David
D
UBC James Hogg Research Centre, Providence Heart+Lung Institute, Department of Pathology and Laboratory Medicine, University of British Columbia, Room 166, Burrard Building, St. Paul's Hospital, 1081 Burrard Street, Vancouver, British Columbia, Canada V6Z 1Y6.
Singhera
Gurpreet K
GK
Utokaparch
Soraya
S
Hackett
Tillie L
TL
Boyd
John H
JH
Luo
Zongshu
Z
Si
Xiaoning
X
Dorscheid
Delbert R
DR
McManus
Bruce M
BM
Hegele
Richard G
RG
D006801:Humans; D053594:Myeloid Differentiation Factor 88 / Q000096:biosynthesis; D010766:Phosphorylation; D012141:Respiratory Tract Infections / Q000821:virology*; D051197:Toll-Like Receptor 4 / Q000502:physiology*; D056189:Viral Tropism; D053586:Virus Internalization; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D051197:Toll-Like Receptor 4; D048051:p38 Mitogen-Activated Protein Kinases