Anaplasma phagocytophilum is an emerging pathogen that causes human granulocytic anaplasmosis. Infection with this zoonotic pathogen affects cell function in both vertebrate host and the tick vector, Ixodes scapularis. Global tissue-specific response and apoptosis signaling pathways were characterized in I. scapularis nymphs and adult female midguts and salivary glands infected with A. phagocytophilum using a systems biology approach combining transcriptomics and proteomics. Apoptosis was selected for pathway-focused analysis due to its role in bacterial infection of tick cells. The results showed tissue-specific differences in tick response to infection and revealed differentiated regulation of apoptosis pathways. The impact of bacterial infection was more pronounced in tick nymphs and midguts than in salivary glands, probably reflecting bacterial developmental cycle. All apoptosis pathways described in other organisms were identified in I. scapularis, except for the absence of the Perforin ortholog. Functional characterization using RNA interference showed that Porin knockdown significantly increases tick colonization by A. phagocytophilum. Infection with A. phagocytophilum produced complex tissue-specific alterations in transcript and protein levels. In tick nymphs, the results suggested a possible effect of bacterial infection on the inhibition of tick immune response. In tick midguts, the results suggested that A. phagocytophilum infection inhibited cell apoptosis to facilitate and establish infection through up-regulation of the JAK/STAT pathway. Bacterial infection inhibited the intrinsic apoptosis pathway in tick salivary glands by down-regulating Porin expression that resulted in the inhibition of Cytochrome c release as the anti-apoptotic mechanism to facilitate bacterial infection. However, tick salivary glands may promote apoptosis to limit bacterial infection through induction of the extrinsic apoptosis pathway. These dynamic changes in response to A. phagocytophilum in I. scapularis tissue-specific transcriptome and proteome demonstrated the complexity of the tick response to infection and will contribute to characterize gene regulation in ticks.

File nymphs_replica 1.raw.zip This file contains the mass spectrometry data of iTRAQ labeled nymph sample (A. phagocytophilum-infected and uninfected control) replicate 1 (RAW.ZIP). Files may be viewed with Thermo Scientific Qual Browser. nymphs_replica 1.raw.zip File nymphs_replica 2.raw.zip This file contains the mass spectrometry data of iTRAQ labeled nymph sample (A. phagocytophilum-infected and uninfected control) replicate 2 (RAW.ZIP). Files may be viewed with Thermo Scientific Qual Browser. nymphs_replica 2.raw.zip File tissues_ replica 1.raw.zip This file contains the mass spectrometry data of iTRAQ labeled adult female gut and salivary gland sample (A. phagocytophilum-infected and uninfected control) replicate 1 (RAW.ZIP). Files may be viewed with Thermo Scientific Qual Browser. tissues_ replica 1.raw.zip File tissues_ replica 2.raw.zip This file contains the mass spectrometry data of iTRAQ labeled adult female gut and salivary gland sample (A. phagocytophilum-infected and uninfected control) replicate 2 (RAW.ZIP). Files may be viewed with Thermo Scientific Qual Browser. tissues_ replica 2.raw.zip Folder RNAseq analysis This folder contains RNAseq data analysis for A. phagocytophilum-infected and uninfected nymphs, guts and salivary glands samples replicates 1 and 2. RNAseq analysis.zip File Sample_Tissues_Ixo_all_samples.fastq.zip This file contains the reads from I. scapularis adult female tissue samples replicates 1 and 2 (FASTQ.ZIP). Sample_Tissues_Ixo_all_samples.fastq.zip File Sample_Nymphs_Ixo_all_samples.fastq.zip This file contains the reads from I. scapularis nymph samples replicates 1 and 2 (FASTQ.ZIP). Sample_Nymphs_Ixo_all_samples.fastq.zip

Peer reviewed