Nitric Oxide production following vaccination with killed mycobacterium Tuberculosis (H37Rv) and BCG

Abstract Background: Protective immune response induced by viable BCG has been suggested by several investigators. Both killed BCG and Mycobacterium tuberculosis are able to induce response. Nitric oxide (NO) is one of the non-specific responses produced against these agents. Objective: To survey the effect of a live, killed BCG and also killed Mycobacterium tuberculosis (H37Rv strain) on NO production. Methods: 6-8-week-old female BALB/c mice were used. Three groups were vaccinated with viable, killed BCG and killed Mtb, respectively. One group received PBS as a control. After 5-8 weeks of vaccination, peritoneal cells of all groups were collected in usual manner and plated out in 96-well plates. Cells were treated with killed H37Rv, killed BCG and viable BCG alone or with rIFN? and NO inhibitors (Aminoguanidine and NGMA). Supernatant of each well was collected after 24h. NO level was estimated by Griess method by ELISA reader at 540nm absorbance. Findings: Results indicated that NO induction level in vaccinated groups were higher than control (P?0.05). Among vaccinated groups, those vaccinated with Mtb produced more NO than the others. Conclusion: Killed Mtb was more potent than the others and should be considered in any planning of new vaccine in term of NO release.