Molecular and immunological characterization of Hyalomma dromedarii and Hyalomma excavatum (Acari: Ixodidae) vectors of Q fever in camels

Abstract

Background and Aim:Q fever Coxiella burnetii is a worldwide zoonotic disease, and C. burnetii was detected in mammals and ticks. Ticks play an important role in the spread of C. burnetii in the environment. Therefore, the aims of this study were to detect Q fever C. burnetii in camels and ixodid ticks by molecular tools and identification of Hyalomma dromedarii and Hyalomma excavatum using molecular and immunological assays.Materials and Methods:A total of 113 blood samples from camels and 190 adult ticks were investigated for the infection with C. burnetii by polymerase chain reaction (PCR) and sequencing the targeting IS30A spacer. The two tick species H. dromedarii and H. excavatum were characterized molecularly by PCR and sequencing of 16S ribosomal RNA (16S rRNA) and cytochrome oxidase subunit-1 (CO1) genes and immunologically by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blot.Results:A total of 52 camels (46%) were positive for Q fever infection. Only 10 adult ticks of H. dromedarii were infected with C. burnetii. The IS30A sequence was around 200 bp in length for C. burnetii in H. dromedarii ticks with a similarity of 99% when compared with reference data in GenBank records. The length of 16S rDNA and CO1 was 440 and 850 bp, respectively, for both H. dromedarii and H. excavatum. The phylogenetic status of H. dromedarii was distant from that of H. excavatum. SDS-PAGE revealed seven different bands in the adult antigens of either H. dromedarii or H. excavatum with molecular weights ranged from 132.9 to 17.7 KDa. In western blot analyses, the sera obtained from either infested camel by H. dromedarii or infested cattle by H. excavatum recognized four immunogenic bands (100.7, 49.7, 43.9, and 39.6 kDa) in H. dromedarii antigen. However, the infested camel sera identified two immunogenic bands (117 and 61.4 kDa) in H. excavatum antigen. Furthermore, the sera collected from cattle infested by H. excavatum recognized three immunogenic bands (61.4, 47.3, and 35 kDa) in H. excavatum antigen.Conclusion:Molecular analyses indicated that both camels and ticks could be sources for infection of animals and humans with Q fever. Furthermore, the molecular analyses are more accurate tools for discriminating H. dromedarii and H. excavatum than immunological tools.

Prevalence and molecular characterization of ticks and tick-borne pathogens of one-humped camels (Camelus dromedarius) in Nigeria

“…The low infection rate of C. burnetii in Hyalomma tick species reported in the present study is comparable with that reported elsewhere for Hyalomma ticks [53,73]. Most of the positives were detected in H. dromedarii and only one in a H. truncatum tick (1.1%).…”

“…Combining several mitochondrial markers (12S, 16S and cox1), we were able to identify several species of Hyalomma ticks. The use of these markers has been increasingly useful for tick identification in several studies [51][52][53][54].…”

“…Most of the positives were detected in H. dromedarii and only one in a H. truncatum tick (1.1%). In a similar study in Egypt, C. burnetii was detected in H. dromedarii exclusively [53], while in China, most of the infection was in H. asiaticum asiaticum [73]. Furthermore, while Coxiellalike bacteria have been found in ticks as endosymbionts and play a role in tick fitness, C. burnetii is responsible for Q fever in vertebrates including humans [3].…”

Sero-prevalence of brucellosis, Q-fever and Rift Valley Fever in humans and livestock in Somali region, Ethiopia

“…In our study, human Q-fever seropositivity was weakly correlated with goats. This is in contrast to previous studies [23, 55, 60], but in line with recent outbreaks in Canada, Australia and Netherlands [18, 61, 62].…”

Molecular Evidence of Influenza A Virus Circulation in African Dromedary Camels Imported to Saudi Arabia, 2017–2018

“…For centuries, camels have played a significant role as a major human companion and a key contributor to the livelihood of mankind. Despite the known role of camels in zoonosis, many aspects of their health have not been studied before the emergence of the Middle East respiratory syndrome-coronavirus (MERS-CoV) in 2012 [1][2][3][4]. In fact, the possibility of spreading known and unknown zoonotic pathogens from camels to humans or other animals represents major public health and economic concerns [4][5][6].…”