Comprehensive RNA-Seq Profiling to Evaluate the Sheep Mammary Gland Transcriptome in Response to Experimental Mycoplasma agalactiae Infection

Abstract

Mycoplasma agalactiae is a worldwide serious pathogen of small ruminants that usually spreads through the mammary route causing acute to subacute mastitis progressing to chronic persistent disease that is hard to eradicate. Knowledge of mechanisms of its pathogenesis and persistence in the mammary gland are still insufficient, especially the host-pathogen interplay that enables it to reside in a chronic subclinical state. This study reports transcriptome profiling of mammary tissue from udders of sheep experimentally infected with M. agalactiae type strain PG2 in comparison with uninfected control animals using Illumina RNA-sequencing (RNA-Seq). Several differentially expressed genes (DEGs) were observed in the infected udders and RT-qPCR analyses of selected DEGs showed their expression profiles to be in agreement with results from RNA-Seq. Gene Ontology (GO) analysis revealed majority of the DEGs to be associated with mycoplasma defense responses that are directly or indirectly involved in host innate and adaptive immune responses. Similar RNA-Seq analyses were also performed with spleen cells of the same sheep to know the specific systemic transcriptome responses. Spleen cells exhibited a comparatively lower number of DEGs suggesting a less prominent host response in this organ. To our knowledge this is the first study that describes host transcriptomics of M. agalactiae infection and the related immune-inflammatory responses. The data provides useful information to further dissect the molecular genetic mechanisms underlying mycoplasma mastitis, which is a prerequisite for designing effective intervention strategies.

Transcriptional profiling of two different physiological states of the yak mammary gland using RNA sequencing

“…In the past few years, the transcriptome has been widely analyzed using microarrays [ 24 – 28 ]. In recent years, however, next-generation sequencing (NGS) technology has been used to explore differentially expressed genes in the mammary gland tissue or milk under different physiological and pathological conditions [ 5 , 17 , 29 – 31 ]. This research has revealed that an abundance of genes plays a very complex and important role in the regulation of lactation and mammary gland tissue health.…”

Immune genes are hotspots of shared positive selection across birds and mammals

“…Finally, we compared the pathogen-mediated transcriptional responses in birds to those in mammals. We used 14 previously published studies that generated transcriptomes for control individuals and pathogen-challenged individuals to identify differentially expressed genes in response to pathogen infection for a species of mammal (Supplementary file 1 Table 11; (Qian et al, 2013; Langley et al, 2014; Ogorevc et al, 2015; Rojas-Peña et al, 2015; DeBerg et al, 2016; Lee et al, 2016; Tran et al, 2016; Chopra-Dewasthaly et al, 2017; de Jong et al, 2018). We chose studies that used similar pathogens as those used in the avian experiments to compare the expression profiles of the two clades as closely as possible, while acknowledging that such matching will necessarily be somewhat imprecise.…”

Gap analysis ofMycoplasma bovisdisease, diagnosis and control: An aid to identify future development requirements

“…RNA‐seq (Wang, Gerstein, & Snyder, ) should also be exploitable to identify genes that are significantly up‐ or down‐regulated during interaction with host cells, or in planktonic versus biofilm lifestyles or during intracellular replication. Dual RNA‐seq approaches, whereby both pathogen and host transcriptional profiles are simultaneously delineated, should inform our understanding of host responses to infection, as has been recently applied to the host mammary response to the related pathogen M. agalactiae (Chopra‐Dewasthaly, Korb, Brunthaler, & Ertl, ). In the initial characterization of the host transcriptional responses in five tissues following intratracheal M. bovis administration, differential expression of 157–994 genes was detected (depending on tissue), with the BPIFA1 , C9 and CD14 genes identified as “key players” in the immune function networks (Behura et al., ).…”