[Frontiers in Bioscience E3, 380-390, January 1, 2011]

Hepatitis D antigens cause growth retardation and brood-size reduction in C. elegans

Li-Wei Lee1, Tsui-Yun Chang3, Hsiao-Wen Lo2, Szecheng J. Lo1,2,3

1Department of Life Science, Chang Gung University, Tao-Yuan 333, Taiwan, 2Graduate Institute of Biomedical Sciences, Chang Gung University, Tao-Yuan 333, Taiwan, 3National Yang-Ming University, School of Life Science, Institute of Microbiology and Immunology, Taipei 112, Taiwan


1. Abstract
2. Introduction
3. Materials and Methods
3.1. Plasmid construction
3.1.1. pFib-LD-SS
3.1.2. pPmyo-2::GFP::icr::DsRed::SD I
3.1.3. pPmyo-2::GFP::icr::DsRed::SD II and pPmyo-2::GFP::icr::DsRed::SD III
3.1.4.pPmyo-2::GFP::icr::DsRed:: SD441, SD327, SD267 and SD201
3.1.5. pHsp16.41::GFP::icr and pHsp16.41::GFP::icr::DsRed::SD I
3.1.6. L-HDAg RNAi construct and feeding experiment
3.2. Worm culture
3.3. Microinjection and microscopy
4. Results
4.1. Phenotypes of transgenic worms expressing hepatitis D antigens
4.2. Mapping the domain of HDAg caused worm growth retardation and brood-size reduction
4.3. Sensitivity of larval stage to HDAg effect
4.4. The effect of various genotypes of HDAg on transgenic worms
5. Discussion
6. Acknowledgement
7. References


Caenorhabditis elegans is a model organism that has been used to study human bacterial and viral pathogenesis. We report here the expression of human hepatitis delta viral antigens (HDAg) in C. elegans and measure the effect on the sterility, growth, and brood size in transgenic worms. Expression of HDAg under two different promoters, fib-1 (a ubiquitous promoter) and myo-2 (a pharynx-specific promoter), was achieved in C. elegans using dicistronic or tricistronic vectors derived from the operon CEOP5428. Transgenic worms expressing HDAg ubiquitously resulted in 20% to 70% sterility while those expressing HDAg in the pharynx displayed 70% sterility. Most of worms expressing HDAg in pharynx were arrested at larvae stage 2 or 3 and displayed a 70% reduction in brood size. Domain mapping experiments suggested that the nuclear localization signal of HDAg is required for the observed effect. Heat-shock induction of HDAg expression revealed that L4 larvae were the most sensitive to brood size reduction. These studies demonstrate that C. elegans can provide an additional model for studying HDAg interactions with host targets.