Surface IgM λ light chain is involved in the binding and infection of infectious bursal disease virus (IBDV) to DT40 cells
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Infectious bursal disease virus (IBDV) is an important immunosuppressive virus in chickens. Surface immunoglobulin M (sIgM)-bearing B lymphocytes act as the major targets of IBDV in the bursa of Fabricius, and sIgM may function as one of the membrane binding sites responsible for IBDV infection. Recently, using the virus overlay protein binding assay, the chicken λ light chain of sIgM was identified to specifically interact with IBDV in a virulence-independent manner in vitro. To further investigate sIgM λ light chain-mediated IBDV binding and infection in pre-B cells, the cell line DT40, which is susceptible to both pathogenic and attenuated IBDV, was used. Based on the RNA interference strategy, the DT40 cell line whose λ light chain of sIgM was stably knocked down, herein termed DT40LKD, was generated by the genomic integration of a specific small hairpin RNA and a green fluorescence protein co-expression construct. Flow cytometry analysis indicated that the binding of IBDV to DT40LKD cells was significantly reduced due to the loss of sIgM λ light chain. In particular, reduced viral replication was observed in IBDV-incubated DT40LKD cells, and no viral release into cell culture medium was detected by the IBDV rapid diagnostic strips. In addition, the rescue of sIgM λ light chain expression restored viral binding and replication in DT40LKD cells. These results show that sIgM λ light chain appears to be beneficial for IBDV attachment and infection, suggesting that sIgM acts as a binding site involved in IBDV infection.
KeywordsDT40 cell Infectious bursal disease virus Lambda light chain Small hairpin RNA Surface immunoglobulin M
We thank all the editors and anonymous reviewers for their helpful suggestions on the quality improvement of our paper. This work was supported by the Fundamental Research Funds for the Central Universities of China (No. 2016-JYB-JSMS-004), Key Program of NSFC-Henan Joint Fund (No. U1604232), the National Natural Science Foundation of China (No. 31602050) and the National Key Research & Development Program of China (No. 2016YFD0500800).
JC, LY, JL, and GZ conceived and designed the experiments. JC, PL, LY, and MT performed the experiments. LY, JL, GZ, and AW analysed the data. JC and LY wrote the paper and designed the figures. All authors read and approved the final manuscript.
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Conflict of interest
The authors declare that there are no conflict of interest.
This article does not contain any studies with animals performed by any of the authors.
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