Identification of some heat-induced genes of Trichinella spiralis

Three heat-induced genes of the infective-stage larvae of Trichinella spira lis were successfully identified by the suppression subtractive hybridizati on (SSH) technique. As indicated by reverse Northern blotting, 19 of 25 clo nes were scored as differentially transcribed in the heat-shocked infective -stage larvae. The sequencing data showed the presence of 12 different gene s. Three were homologous to histone H3, histone H2B and translationally con trolled tumour protein (TCTP). A 0.6 kb cDNA of histone H3 was generated by the RACE method and sequenced. It contained an open reading frame of 136 a mino acids that demonstrated 94% identity with genes from Drosophila hydei. Semi-quantitative RT-PCR indicated that after heat-shock treatment, the ex pression levels of histone H3, historic H2B and TCTP increased 4.8, 27 and 5.7-fold, respectively. Northern analysis confirmed the upregulation of his tone H3, historic H2B and TCTP transcripts. The upregulation of these genes during stress conditions has not been reported in parasitic organisms. The stress proteins may play an active role to sustain the parasite after expo sure to hostile host factors.