Detection and quantification of Parascaris P-glycoprotein drug transporter expression with a novel mRNA hybridization technique

Macrocyclic lactone-resistant Parascaris have been reported throughout the world. In part, the drug resistant phenotype is hypothesized to be associated with ATP-binding cassette transporters known as P-glycoproteins. In many systems, P-glycoproteins efflux drugs out of cells thereby precluding drug binding to target receptors. Parascaris may evade macrocyclic lactone-mediated death by effluxing drugs away from target receptors in the nervous system. Alternatively, P-glycoprotein expression in the gut or body wall could prevent penetration of drugs into the body of the parasite altogether. In the present study, we evaluate expression of Peq-pgp-11 and Peg-pgp-T-16 using a novel multiple nucleic acid hybridization method. This method allowed for visualization of individual mRNA transcripts within fixed tissue sections of Parascaris adults. Our investigation revealed expression of Peq-pgp-11 and Peq-pgp-16 in the intestine, body wall, nerves, lateral cords, and reproductive tissues of male and female parasites. These results suggest that Pgp could efflux drugs locally at the level of parasite neuronal tissue as well as at sites of entry for drugs such as the hypodermis and intestine. The multiple nucleic acid hybridization method could be useful for providing tissue context for gene expression in a variety of nematode parasites.