Molecular detection of Coxiella (Gammaproteobacteria: Coxiellaceae) in Argas persicus and Alveonasus canestrinii (Acari: Argasidae) from Iran

Coxiella R1 symbiont regulates the Asian long-horned tick on its reproduction and development

The Asian long-horned tick Haemaphysalis longicornis, is a hematophagous ectoparasite that causes important public and veterinary health concerns. Different species of ticks harbor a symbiont bacterium of the genus Coxiella. A Coxiella sp. bacterial endosymbiont was highly prevalent in laboratory-reared H. longicornis. The endosymbiont sequence was 100 % identical to those of H. longicornis Coxiella-like endosymbionts and thus named Coxiella R1 in the present study. Coxiella R1 was detected in all stages of tick and in greatest numbers in nymphs and unfed adult females. We manipulated the numbers of Coxiella R1 in ticks by injecting engorged females or capillary tube feeding of flat females with tetracycline. Both of the administration routes were efficient in reducing the symbiont densities. Microinjection of tetracycline solution reduced 25.53 % of Coxiella R1 in eggs harvested just before hatching, whereas, the reduction rate for capillary tube feeding climbed to 81.70 %. Ticks with Coxiella R1 suppression laid abnormal eggs which were wrinkled, flat, and black, and linked each other to form a line. Ticks that had been treated with tetracycline had lower hatching rates in comparison to controls. In addition, larvae with tetracycline treatment less infested hosts and thus had lower engorgement rates than ticks that received PBS alone. The findings indicate that Coxiella R1 is a primary and obligate endosymbiont, and capable of modulating the obligately hematophagous parasites in egg laying and hatching, and larva blood feeding. The results also suggest that tetracycline treatment could be added to an integrated pest management tool menu for control of the Asian long-horned ticks.

Absence of Coxiella burnetii in kangaroo ticks (Amblyomma triguttatum) from a high seroprevalence population of eastern grey kangaroos

Q fever, caused by Coxiella burnetii, is an important zoonotic and public health concern worldwide. Kangaroos are thought to be a likely wildlife reservoir for C. burnetii in Australia and the kangaroo tick (Amblyomma triguttatum) has often been considered a vector. In this descriptive study of ticks collected from a population of eastern grey kangaroos (Macropus giganteus) with a high serological (84 %) and molecular (65 %) prevalence of C. burnetii in northern New South Wales, a total of 72 A. triguttatum ticks were tested by PCRs targeting the IS1111, htpAB, and com1 genes of the Coxiella genome. Despite the remarkably high prevalence of coxiellosis in the host population, none of the ticks were positive for Coxiella. This finding suggests that the kangaroo tick may not play a significant role in the transmission dynamics of C. burnetii in this particular host population.

Molecular detection of Coxiella burnetii in tick and blood samples from small ruminants in northwest of Iran

This survey sought to molecularly detect Coxiella burnetii in Argasidae and Ixodidae ticks attached to small ruminants in the region of West Azerbaijan (Northwest of Iran) and blood samples collected from the same animals. 451 tick samples and 927 blood samples were obtained from sheep (n = 536) and goats (n = 391) and tested by nested PCR for detection of C. burnetii insertion sequence IS1111 or icd gene sequence. The collected ticks were morphologically classified as Rhipicephalus sanguineus, Rhipicephalus turanicus, Hyalomma asiaticum, Hyalomma anatolicum, or Argas reflexus. 14% of ticks (65 in total 43 for IS1111 and 22 for icd gene) tested positive for C. burnetii, none of which were from the Argas genus. Among the 927 blood samples, 218 (23.5%) tested positive for C. burnetii. The positive result from analysis targeting the genes IS1111 and icd were 131 and 87 respectively. As Q fever is a tickborne zoonosis and endemic to Iran, such information is critical for creating effective, coordinated, and strategic tick and pathogen control programs to prevent disease outbreak in domestic animals and humans.

Microbiome analysis of the midguts of different developmental stages of Argas persicus in China

Argas persicus is an ectoparasite of poultry. The bacterial community structure and the pathogenic bacteria associated with different developmental stages of A. persicus have implications for control. Argas persicus were collected from chickens in the city of Jiuquan in Gansu, China. Bacterial DNA was extracted from the midgut contents of blood engorged larvae, nymphs and adult females. The V3-V4 hypervariable regions of 16S rRNA genes were sequenced using the IonS5™XL platform. Identification of Rickettsia spp. and detection of Coxiella burnetii were performed using PCR on target genes. The bacterial diversity within larvae was the highest and the bacterial diversity within nymphs was greater than that of adults. At different classification levels, seven bacterial phyla were common phyla, 27 genera were common genera, and 18 species were common species in the three samples. At the phylum level, Proteobacteria showed a marked predominance in all samples. Rickettsia, Stenotrophomonas, Spiroplasma, and Coxiella were the dominant bacteria at the genus level. The Rickettsia species in A. persicus was identified as Rickettsia hoogstraalii and the Coxiella species was identified as a Coxiella-like endosymbiont. Additionally, some bacterial species such as Pseudomonas geniculata, Sphingomonas koreensis, and Acinetobacter haemolyticus were reported here for the first time in A. persicus.

Novel Genotypes of Nidicolous Argas Ticks and Their Associated Microorganisms From Spain

The knowledge of the distribution, richness and epidemiological importance of soft ticks of the genus Argas is incomplete. In Spain, five Argas species have been recorded, including three ornitophilic nidicolous ticks, but their associated microorganisms remain unknown. This study aimed to investigate ticks from bird nests and their microorganisms. Ticks were collected extensively from natural cavities and nest-boxes used by European rollers (Coracias garrulus) and little owls (Athene noctua) in Southeastern and Central Spain. Ticks were morphologically and genetically identified and corresponding DNA/RNA tick extracts were analyzed [individually (n = 150) or pooled (n = 43)] using specific PCR assays for bacteria (Anaplasmataceae, Bartonella, Borrelia, Coxiella/Rickettsiella, and Rickettsia spp.), viruses (Flaviviruses, Orthonairoviruses, and Phenuiviruses), and protozoa (Babesia/Theileria spp.). Six Argas genotypes were identified, of which only those of Argas reflexus (n = 8) were identified to the species level. Two other genotypes were closely related to each other and to Argas vulgaris (n = 83) and Argas polonicus (n = 33), respectively. These two species have not been previously reported from Western Europe. Two additional genotypes (n = 4) clustered with Argas persicus, previously reported in Spain. The remaining genotype (n = 22) showed low sequence identity with any Argas species, being most similar to the African Argas africolumbae. The microbiological screening revealed infection with a rickettsial strain belonging to Rickettsia fournieri and Candidatus Rickettsia vini group in 74.7% of ticks, mainly comprising ticks genetically related to A. vulgaris and A. polonicus. Other tick endosymbionts belonging to Coxiella, Francisella and Rickettsiella species were detected in ten, one and one tick pools, respectively. In addition, one Babesia genotype, closely related to avian Babesia species, was found in one tick pool. Lastly, Anaplasmataceae, Bartonella, Borrelia, and viruses were not detected. In conclusion, five novel Argas genotypes and their associated microorganisms with unproven pathogenicity are reported for Spain. The re-use of nests between and within years by different bird species appears to be ideal for the transmission of tick-borne microorganisms in cavity-nesting birds of semiarid areas. Further work should be performed to clarify the taxonomy and the potential role of soft Argas ticks and their microorganisms in the epidemiology of zoonoses.