N-Linked glycosylation is essential for the yellow head virus replication cycle.
Yellow head virus (YHV) particles contain a nucleocapsid protein (p20) and two envelope glycoproteins (gp116 and gp64). The glycans attached to the two glycoproteins are N-linked and are complex and high mannose types, respectively. Here, we show that treatment with the N-linked glycosylation inhibitor tunicamycin in YHV-infected black tiger shrimp (Penaeus monodon) resulted in less severe yellow head disease and reduced mortality when compared with untreated control shrimp. Quantitative real-time reverse transcription PCR analysis also revealed lower YHV copy numbers in the haemolymph of treated than control shrimp. This was concurrent with less intense immuno-reactions in tissues of treated versus untreated shrimp using mAbs against all three YHV structural proteins. In addition, transmission electron microscopy of lymphoid organ tissue of the treated and untreated shrimp [eight collected at 36 h and eight at 48 h post-infection (p.i.)] revealed only unenveloped nucleocapsids in all but one of the treated shrimp (collected at 48 h p.i.). By contrast, all the untreated shrimp showed a mixture of many unenveloped and enveloped virions. These results were supported by purification of YHV from the cell-free haemolymph of treated and untreated shrimp followed by YHV structural protein analysis by SDS-PAGE. It revealed three expected structural protein bands (116, 64 and 20 kDa) from the untreated shrimp but no structural protein bands from the tunicamycin-treated shrimp (confirmed by Western blot analysis). Overall, the results indicated that blocking glycosylation with tunicamycin inhibited the formation of mature YHV virions and their subsequent release into shrimp haemolymph, reducing the severity of disease.
CENTEX SHRIMP, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.|National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Thailand Science Park, Klong Luang, Patumthani 12120, Thailand.
Chumporn
C
Soowannayan
CENTEX SHRIMP, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
Nhuengtida
N
Chanarpakorn
CENTEX SHRIMP, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
Mongkhol
M
Phanthura
CENTEX SHRIMP, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
Nattawoot
N
Deekhlai
CENTEX SHRIMP, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
Chanon
C
Kunasol
CENTEX SHRIMP, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
Siriporn
S
Sriurairatana
D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D006031:Glycosylation; D006458:Hemolymph / Q000821:virology; D008562:Membrane Glycoproteins; D033561:Penaeidae / Q000187:drug effects* / Q000821:virology; D011134:Polysaccharides / Q000378:metabolism*; D046828:Roniviridae / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D014415:Tunicamycin / Q000494:pharmacology*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins; D014771:Virion / Q000187:drug effects / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects*
D000998:Antiviral Agents; D008562:Membrane Glycoproteins; D011134:Polysaccharides; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C040496:gp 118 protein, Herpesvirus 3, Human; D014415:Tunicamycin