Marek's disease virus (MDV) encodes an interleukin-8 homolog (vIL-8): characterization of the vIL-8 protein and a vIL-8 deletion mutant MDV.
Chemokines induce chemotaxis, cell migration, and inflammatory responses. We report the identification of an interleukin-8 (IL-8) homolog, termed vIL-8, encoded within the genome of Marek's disease virus (MDV). The 134-amino-acid vIL-8 shares closest homology to mammalian and avian IL-8, molecules representing the prototype CXC chemokine. The gene for vIL-8 consists of three exons which map to the BamHI-L fragment within the repeats flanking the unique long region of the MDV genome. A 0.7-kb transcript encoding vIL-8 was detected in an n-butyrate-treated, MDV-transformed T-lymphoblastoid cell line, MSB-1. This induction is essentially abolished by cycloheximide and herpesvirus DNA polymerase inhibitor phosphonoacetate, indicating that vIL-8 is expressed with true late (gamma2) kinetics. Baculovirus-expressed vIL-8 was found to be secreted into the medium and shown to be functional as a chemoattractant for chicken peripheral blood mononuclear cells but not for heterophils. To characterize the function of vIL-8 with respect to MDV infection in vivo, a recombinant MDV was constructed with a deletion of all three exons and a soluble-modified green fluorescent protein (smGFP) expression cassette inserted at the site of deletion. In two in vivo experiments, the vIL-8 deletion mutant (RB1BvIL-8DeltasmGFP) showed a decreased level of lytic infection in comparison to its parent virus, an equal-passage-level parent virus, and to another recombinant MDV containing the insertion of a GFP expression cassette at the nonessential US2 gene. RB1BvIL-8DeltasmGFP retained oncogenicity, albeit at a greatly reduced level. Nonetheless, we have been able to establish a lymphoblastoid cell line from an RB1BvIL-8DeltasmGFP-induced ovarian lymphoma (MDCC-UA20) and verify the presence of a latent MDV genome lacking vIL-8. Taken together, these data describe the identification and characterization of a chemokine homolog encoded within the MDV genome that is dispensable for transformation but may affect the level of MDV in vivo lytic infection.
Parcells
M S
MS
Center of Excellence for Poultry Science, Department of Poultry Science, University of Arkansas, Fayetteville, Arkansas 72701, USA. parcells@uark.edu
Lin
S F
SF
Dienglewicz
R L
RL
Majerciak
V
V
Robinson
D R
DR
Chen
H C
HC
Wu
Z
Z
Dubyak
G R
GR
Brunovskis
P
P
Hunt
H D
HD
Lee
L F
LF
Kung
H J
HJ
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D016367:Baculoviridae / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D002461:Cell Line, Transformed; D002630:Chemotactic Factors / Q000235:genetics*; D002645:Chickens; D003001:Cloning, Molecular; D003513:Cycloheximide; D017353:Gene Deletion; D049452:Green Fluorescent Proteins; D008381:Herpesvirus 2, Gallid / Q000235:genetics / Q000276:immunology*; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010746:Phosphonoacetic Acid; D012333:RNA, Messenger / Q000032:analysis; D011994:Recombinant Proteins / Q000096:biosynthesis; D016415:Sequence Alignment; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics; D014779:Virus Replication
D002630:Chemotactic Factors; D016209:Interleukin-8; D008164:Luminescent Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014764:Viral Proteins; D049452:Green Fluorescent Proteins; D003513:Cycloheximide; D010746:Phosphonoacetic Acid