Due to scarcity of bacilli, an accurate diagnosis of osteoarticular tuberculosis is always being a challenge. Though conventional methods lack sensitivity and are time consuming, molecular diagnostic modalities are very effective for early diagnosis with high sensitivity and specificity. Timely diagnosis even in latent period will improve the efficacy of the treatment of osteoarticular tuberculosis. Under some stress conditions like hypoxia, nitric oxide stress, long term viability of M. tuberculosis is favoured by alpha crystallin protein (acr), which is adominant protein of latent phase. In this article we focus on protein that shows significant expression in the latent phase of M.tuberculosis. It may be further used as a prognostic biomarker for differentiating latent and active tuberculosis.