Bartonella infections are prevalent in rodents despite efficient immune responses

Abstract

Background Pathogens face strong selection from host immune responses, yet many host populations support pervasive pathogen populations. We investigated this puzzle in a model system of Bartonella and rodents from Israel’s northwestern Negev Desert. We chose to study this system because, in this region, 75–100% of rodents are infected with Bartonella at any given time, despite an efficient immunological response. In this region, Bartonella species circulate in three rodent species, and we tested the hypothesis that at least one of these hosts exhibits a waning immune response to Bartonella, which allows reinfections. Methods We inoculated captive animals of all three rodent species with the same Bartonella strain, and we quantified the bacterial dynamics and Bartonella-specific immunoglobulin G antibody kinetics over a period of 139 days after the primary inoculation, and then for 60 days following reinoculation with the same strain. Results Contrary to our hypothesis, we found a strong, long-lasting immunoglobulin G antibody response, with protective immunological memory in all three rodent species. That response prevented reinfection upon exposure of the rodents to the same Bartonella strain. Conclusions This study constitutes an initial step toward understanding how the interplay between traits of Bartonella and their hosts influences the epidemiological dynamics of these pathogens in nature. Graphical Abstract

Epidemiology of Bartonella henselae infection in pet and stray cats in Croatia with risk factors analysis

“…Furthermore, recent studies have shown that antibodies provide sufficient protection against Bartonella spp. by preventing their attachment to red blood cells [ 73 ], but also by long-term prevention of reinfection with the same strain [ 74 ]. This supports earlier hypotheses that younger animals could lack the protection due to their undeveloped antibodies [ 15 , 21 , 50 ], although more verification of this possibility is required.…”

Parasite contingency loci and the evolution of host specificity: Simple sequence repeats mediateBartonellaadaptation to a wild rodent host

“…In this region, a diverse collection of Bartonella strains circulates in communities with varying compositions of rodent host species including mainly Gerbillus andersoni and Gerbillus pyramidum 8,9 . Bartonella are prevalent in these rodent populations despite high strain turnover rates 10–12 . Infections with any individual strain are cleared by the host immune system, and that strain is subsequently unable to reinfect the same host 10 .…”

“…Bartonella are prevalent in these rodent populations despite high strain turnover rates 10–12 . Infections with any individual strain are cleared by the host immune system, and that strain is subsequently unable to reinfect the same host 10 . This strong selection pressure from immune responses, coupled with the availability of multiple hosts, may favor Bartonella that have evolved the capacity to readily adapt to different host environments.…”