Interaction of Strains of Different Sources and Genotypes with Bovine and Human Monocyte-Derived Macrophages.

Most human Q fever infections originate from small ruminants. By contrast, highly prevalent shedding of (.) by bovine milk rarely results in human disease. We hypothesized that primary bovine and human monocyte-derived macrophages (MDM) represent a suitable model for the identification of strain-specific virulence properties at the cellular level. Twelve different strains were selected to represent different host species and multiple loci variable number of tandem repeat analysis (MLVA) genotypes. Infection efficiency and replication of were monitored by cell culture re-titration and qPCR. Expression of immunoregulatory factors after MDM infection was measured by qRT-PCR and flow cytometry. Invasion, replication and MDM response differed between strains but not between MDMs of the two hosts. trains isolated from ruminants were less well internalized than isolates from humans and rodents. Internalization of MLVA group I strains was lower compared to other genogroups. Replication efficacy of in MDM ranged from low (MLVA group III) to high (MLVA group IV). Infected human and bovine MDM responded with a principal up-regulation of pro-inflammatory cytokines such as IL-1β, IL-12, and TNF-α. However, MLVA group IV strains induced a pronounced host response whereas infection with group I strains resulted in a milder response. infection marginally affected polarization of MDM. Only one strain of MLVA group IV caused a substantial up-regulation of activation markers (CD40, CD80) on the surface of bovine and human MDM. The study showed that replication of in MDM and the subsequent host cell response is genotype-specific rather than being determined by the host species pointing to a clear distinction in virulence between the genetic groups.