Characterization and comparison of differentially expressed genes involved in Chlamydia psittaci persistent infection in vitro and in vivo.

[Display omitted] • Transcriptome analysis of an in vitro model of IFN-γ-mediated C. psittaci persistence in HeLa cells. • 68 genes were up-regulated and 109 genes were down-regulated during persistent infection of C. psittaci in HeLa cells by cDNA microarrays assays. • Amoxicillin treatment could induce a non-infectious but viable (persistent) state in C. psittaci infected BALB/c mice. • Amoxicillin-exposed organisms three genes up regulates and five genes down-regulated expression of a panel of genes similar to that transcribed by cDNA microarrays assays in vitro , providing important insights towards understanding the potential targets of chlamydial persistence. Chlamydia psittaci is an obligate intracellular zoonotic pathogen that can enter a persistence state in host cells. While the exact pathogenesis is not well understood, this persistence state may play an important role in chronic Chlamydia disease. Here, we assess the effects of chlamydial persistence state in vitro and in vivo by transmission electron microscopy (TEM) and cDNA microarray assays. First, IFN-γ-induced C. psittaci persistence in HeLa cells resulted in the upregulation of 68 genes. These genes are involved in protein translation, carbohydrate metabolism, nucleotide metabolism, lipid metabolism and general stress. However, 109 genes were downregulated following persistent C. psittaci infection, many of which are involved in the TCA cycle, expression regulation and transcription, protein secretion, proteolysis and transport, membrane protein, presumed virulence factor, cell division and late expression. To further study differential gene expression of C. psittaci persistence in vivo , we established an experimentally tractable mouse model of C. psittaci persistence. The C. psittaci -infected mice were gavaged with either water or amoxicillin (amox), and the results indicated that the 20 mg/kg amox-exposed C. psittaci were viable but not infectious. Differentially expressed genes (DEGs) screened by cDNA microarray were detected, and interestingly, the results showed upregulation of three genes (euo , ahpC , prmC) and downregulation of five genes (pbp3 , sucB_1 , oppA_4 , pmpH , ligA) in 20 mg/kg amox-exposed C. psittaci , which suggests that antibiotic treatment in vivo can induce chlamydial persistence state and lead to differential gene expression. However, the discrepancy on inducers between the two models requires more research to supplement. The results may help researchers better understand survival advantages during persistent infection and mechanisms influencing C. psittaci pathogenesis or evasion of the adaptive immune response. [ABSTRACT FROM AUTHOR]