Cloning and expression pattern of a heat shock cognate protein 70 gene in ticks (Haemaphysalis flava)

Ticks and tick-borne-diseases have serious public health implications, and screening feasible protein candidates for vaccines development is identified to be an effective alternative to control of tick infestations. In current study, we focused on cloning the full-length gene encoding a heat shock cognate protein 70 (Hsc70), a molecular chaperone of critical functional roles belonging to heat shock protein 70 (HSP70) family, in salivary glands of Haemaphysalis flava, namely Hf-Hsc70, and analyzing the expression of Hf-Hsc70 in different life phases, organs and ambient temperatures. Rapid amplification of cDNA ends (RACE) was performed to amplify the 5' and 3' ends of Hf-Hsc70. The expression profiles of Hf-Hsc70 were studied by semi-quantitative real-time PCR (RT-PCR). The full-length of Hf-Hsc70 was 2363 bp, and contained an ORF of 1965 bp encoding a protein of 648 amino acids. The expression levels of Hf-Hsc70 at different life phases were in the order of female larvae < female fully engorged nymphs < male adult ticks < female full engorged adult ticks < female half engorged adult ticks. The relative expression of Hf-Hsc70 in salivary glands was steadily higher than that in midguts (p < 0.05) regardless of feeding status. A 3-h of heat stress did not significantly induce the up-regulation of Hf-Hsc70 transcription. These results indicated that Hf-Hsc70 was a constitutive form of HSP70 family, and its expression pattern in different life phases and organs suggested a possible role in blood feeding, which would further make Hsc70 a potential candidate for the development of vaccines against ticks.