Biotic and abiotic factors shape the microbiota of wild-caught populations of the arbovirus vector Culicoides imicola.

Biting midges of the genus Culicoides are known vectors of arboviruses affecting human and animal health. However, little is known about Culicoides imicola microbiota and its influence on this insect's biology. In this study, the impact of biotic and abiotic factors on C. imicola microbiota was characterized using shotgun-metagenomic sequencing of whole-body DNA samples. Wild-caught C. imicola adult nulliparous females were sampled in two locations from Sicily, Italy. The climatic variables of temperature and soil moisture from both localities were recorded together with potential host bloodmeal sources. Shared core microbiome among C. imicola populations included Pseudomonas, Escherichia, Halomonas, Candidatus Zinderia, Propionibacterium, and Schizosaccharomyces. Specific and unique taxa were also found in C. imicola from each location, highlighting similarities and differences in microbiome composition between the two populations. DNA and protein identification showed differences in host preferences between the two populations, with Homo sapiens and Canis lupus familiaris L. being the preferred bloodmeal source in both locations. A principal component analysis showed that the combined effect of host preferences (H. sapiens) and local soil moisture factors shape the microbiome composition of wild-caught populations of C. imicola. These results contribute to characterizing the role of the microbiome in insect adaptation and its utility in predicting geographic expansion of Culicoides species with potential implications for the control of vector-borne diseases.

Molecular detection and characterization of spotted fever group rickettsiae in ticks from Central Italy.

The aim of this study was to investigate the presence of rickettsial pathogens in ticks from Central Italy. A total of 113 ticks hailed from Latium and Tuscany regions were identified and tested by PCR to detect gltA, ompA, ompB genes of Rickettsia. Positive amplicons were sequenced and identified at species level. Ticks were analyzed individually or in pools. The percentage of positivity for SFG rickettsiae was 12.4%, expressed as minimum infection rate (MIR) assuming that one tick was positive in each positive pool. Rickettsia aeschlimannii was detected in Hyalomma marginatum, Rickettsia monacensis in Ixodes ricinus and Rickettsia massiliae and Rickettsia conorii in Rhipicephalus sanguineus sensu lato. These findings confirm the circulation of pathogenic rickettsiae in Latium and Tuscany regions. To our knowledge this is the first report of R. massiliae in Latium region.

Detection of natural killer T cells in mice infected with Rickettsia conorii.

Little information is available regarding the role of natural killer T (NKT) cells during the early stage of Rickettsia conorii infection. Herein, C3H/HeN mice were infected with the Malish 7 strain of R. conorii. Splenocytes from these mice were analysed in the early stage of the infection by flow cytometry and compared with uninfected controls. Our results showed an increase in NKT cells in infected mice. Additionally, NKT interleukin (IL)-17(+) cells increased three days after infection, together with a concurrent decrease in the relative amount of NKT interferon (IFN)-γ(+) cells. We also confirmed a higher amount of NK IFN-γ(+) cells in infected mice. Taken together, our data showed that NKT cells producing Il-17 increased during the early stage of rickettsial infection. These results suggest a connection between IL-17(+) NKT cells and vasculitis, which is the main clinical symptom of rickettsiosis.

A Molecular survey of Anaplasma spp., Rickettsia spp., Ehrlichia canis and Babesia microti in foxes and fleas from Sicily.

Fleas (Insecta: Siphonaptera) are obligate bloodsucking insects, which parasitize birds and mammals, and are distributed throughout the world. Several species have been implicated in pathogen transmission. This study aimed to monitor red foxes and the fleas isolated from them in the Palermo and Ragusa provinces of Sicily, Italy, as these organisms are potential reservoirs and vectors of pathogens. Thirteen foxes (Vulpes vulpes) and 110 fleas were analysed by polymerase chain reaction (PCR) to detect DNA of the pathogens Ehrlichia canis, Babesia microti, Rickettsia spp., Anaplasma phagocytophilum, Anaplasma platys, Anaplasma marginale and Anaplasma ovis. In the foxes, A. ovis was detected in only one animal, whereas the prevalence of the E. canis pathogen was 31%. B. microti and Rickettsia spp. were not detected. Of all of the collected fleas, 75 belonged to the species Xenopsylla cheopis, 32 belonged to Ctenocephalides canis, two belonged to Ctenocephalides felis and one belonged to Cediopsylla inaequalis. In the fleas, the following pathogens were found: A. ovis (prevalence 25%), A. marginale (1%), A. phagocytophilum (1%), Rickettsia felis (2%) and E. canis (3%). X. cheopis was the flea species most frequently infected with Anaplasma, in particular A. ovis (33%), A. marginale (1%) and A. phagocytophilum (1%). Both C. felis exemplars were positive for R. felis. E. canis was found in the lone C. inaequalis and also in 3% of the X. cheopis specimens. No fleas were positive for B. microti or A. platys. As foxes often live in proximity to domestic areas, they may constitute potential reservoirs for human and animal parasites. Further studies should be performed on fleas to determine their vectorial capacity.

Characterization of the apical membrane antigen-1 in Italian strains of Babesia bigemina.

Babesia bigemina is a parasite endemic in different parts of the world, including Europe and the Americas. One of the few genes characterized in this species codifies for the Apical Membrane Antigen 1 (AMA-1), a trans-membrane antigen recently identified. In this research, we characterized the ama-1 gene from three Italian B. bigemina strains, two B. bigemina strains obtained from Ragusa, Sicily (ITA1 and ITA3) and a third one obtained from Benevento, Campania (ITA2). Italian sequences were compared with those of the Australian strain obtained from the Sanger Institute web site and to strains from different parts of the world. The results obtained confirmed that this newly described ama-1 gene is highly conserved among Italian and foreign strains which has implications for vaccine development.