Copy number variations in mitochondrial DNA has a potent role in parasitic immunity against Haemonchus contortus- A novel report

Mitochondria is a cellular organelle responsible for a variety of function, apart from energy production through oxidative phosphorylation, TCA cycle, apoptosis, plays a major role in iron and calcium metabolism and immune functions against pathogens (bacterial, viral or parasitic). Unlike nucleus, mitochondria exist in multiple copies, with many copies of mitochondrial DNA. A metabolically active cell possess about 10 ³ and 10 ⁴ copies of the mitochondrial genome. Lowered mtDNA copy number leads to disorders or disease, in a similar way as mutation in mtDNA causes a wide range of disease or disorders. In this current article, we estimated mtDNA copy number through QPCR analysis of cytochrome B gene and revealed that healthy individuals have better mtDNA copy number compared to that of the infected ones under natural challenge in sheep model against the parasite Haemonchus contortus infection. We diagnosed the infected animals for H. contortus primarily with symptoms, followed by Faecal egg count and final confirmation through molecular diagnosis. We had characterized the cytochrome B gene from abomasum(stomach) of sheep, which is the site of predilection of this parasite. In our lab, earlier we have documented certain immune response nuclear genes to have antiparasitic role. We had reported the mutations in cytochrome B leading to debility and disease in sheep. Quantitative expression profile for cytochrome B is an indication of the copy number of mitochondrial genes and we observed significantly better expression profile of cytochrome B in healthy sheep in comparison to infected one. Thus, mitochondrial copy number is directly associated with antiparasitic immunity, first time reported.