Identification of immune-associated genes involved in latent Mycobacterium marinum infection.

Tuberculosis (TB) is a high mortality infectious disease caused by Mycobacterium tuberculosis (Mtb), and often develops into latent infection. About 5～10% of latent infections turn into active tuberculosis when the host immune system becomes deficient. Therefore, exploring the latent infection mechanism of Mtb is pivotal for the prevention and treatment of tuberculosis. We first established the zebrafish latent infection model and the chronic infection model utilizing Mycobacterium marinum, which has the highly similar gene background to Mtb. Using the latent infection model, we characterized the gene expression profiles and found 462 genes expressed differentially in the latent period and chronic tuberculosis infection. These differentially expressed genes are involved in various biological processes including transcription, transcriptional regulation, organism development, and immune responses. Among them, nineteen immune-related genes were found to express differentially in the latent period. By analyzing immune related protein network, the genes in the center of the network, including Nos2b, TNFα, IL1, TNFβ, TLR1, TLR2, and TLR4b, displayed significant deferential expression in latent infection and chronic infection period of zebrafish, suggesting that these genes might play an important role in controlling latent infection of Mtb. Identifying immune biomarker related to the status of tuberculosis latent infection might lead to novel strategy for diagnosis and treatment.