Ontogenetic profile of Antiviral Mx gene and its role in innate immunity in Mrigal, Cirrhinusmrigala (Hamilton 1822).

Abstract

The aim of this study was to determine the ontogeny of antiviral Mx gene expression in different stages of development of Cirrhinus mrigala (mrigal). For this purpose, three experiments were designed; in the first experiment, Mx expression was observed in eggs, milt, poly I:C treated twitching stage and control twitching stage, and the Mx expression was maximum in eggs. In the second experiment, upregulation of Mx transcript was studied in hatchling stages of mrigal after poly I:C induction by bath treatment, while control hatchlings were studied as such. Hatchlings (both control and treated) were collected at 2‐, 4‐, 6‐ and 8‐h interval after 24, 48, 72 and 96 h of poly I:C induction. The Mx gene expression showed an increasing trend up to 72 h, where it was highest 3.3‐fold higher than the control and then decreased at 96 h where it was threefold higher when compared to the control. In the third experiment, expression of Mx transcript was studied in mrigal fry after intramuscular stimulation with poly I:C for a duration of 28 days. A gradual upregulation of Mx transcript was seen for the experimental period of 28 days. From the study, it is concluded that Mx gene is transmitted from egg and twitching stages and reduced in larvae and fry. Hence, ontogenically, without poly I:C induction, Mx gene is constitutively expressed at early stages indicating the antiviral defences transmitted from parents to offspring in the process of embryonic development. This indicates there is an antiviral Mx defence mechanism playing at early stages of the development for a period of 45 days.