Porin Expression Profiles in Haemaphysalis longicornis Infected With Babesia microti

Weiqing Zheng; Rika Umemiya-Shirafuji; Qian Zhang; Kiyoshi Okado; Paul Franck Adjou Moumouni; Hiroshi Suzuki; Haiying Chen; Mingming Liu; Xuenan Xuan

doi:10.3389/fphys.2020.00502

Porin Expression Profiles in Haemaphysalis longicornis Infected With Babesia microti

Front Physiol. 2020 May 19:11:502. doi: 10.3389/fphys.2020.00502. eCollection 2020.

Authors

Weiqing Zheng^{1

2}, Rika Umemiya-Shirafuji¹, Qian Zhang³, Kiyoshi Okado¹, Paul Franck Adjou Moumouni¹, Hiroshi Suzuki¹, Haiying Chen², Mingming Liu¹, Xuenan Xuan¹

Affiliations

¹ National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
² The Collaboration Unit for Field Epidemiology of State Key Laboratory for Infectious Disease Prevention and Control, Jiangxi Provincial Key Laboratory of Animal-origin and Vector-Borne Diseases, Nanchang Center for Disease Control and Prevention, Nanchang, China.
³ The Ophthalmology Department, The Second Affiliated Hospital of Nanchang University, Nanchang, China.

Abstract

The porin gene is widely disseminated in various organisms and has a pivotal role in the regulation of pathogen infection in blood-sucking arthropods. However, to date, information on the porin gene from the Haemaphysalis longicornis tick, an important vector of human and animal diseases, remains unknown. In this study, we identified the porin gene from H. longicornis and evaluated its expression levels in Babesia microti-infected and -uninfected H. longicornis ticks at developmental stages. We also analyzed porin functions in relation to both tick blood feeding and Babesia infection and the relationship between porin and porin-related apoptosis genes such as B-cell lymphoma (Bcl), cytochrome complex (Cytc), caspase 2 (Cas2), and caspase 8 (Cas8). The coding nucleotide sequence of H. longicornis porin cDNA was found to be 849 bp in length and encoded 282 amino acids. Domain analysis showed the protein to contain six determinants of voltage gating and two polypeptide binding sites. Porin mRNA levels were not significantly different between 1-day-laid and 7-day-laid eggs. In the nymphal stage, higher porin expression levels were found in unfed, 12-h-partially-fed (12 hPF), 1-day-partially-fed (1 dPF), 2 dPF nymphs and nymphs at 0 day post-engorgement (0 dAE) vs. nymphs at 2 dAE. Cytc and Cas2 mRNA levels were higher in 2 dPF nymphs in contrast to nymphs at 2 dAE. Porin expression levels appeared to be higher in the infected vs. uninfected nymphs during blood feeding except at 1 dPF and 0-1 dAE. Especially, the highest B. microti burden negatively affected porin mRNA levels in both nymphs and female adults. Porin knockdown affected body weight and Babesia infection levels and significantly downregulated the expression levels of Cytc and Bcl in H. longicornis female ticks. In addition, this study showed that infection levels of the B. microti Gray strain in nymphal and female H. longicornis peaked at or around engorgement from blood feeding to post engorgement. Taken together, the research conducted in this study suggests that H. longicornis porin might interfere with blood feeding and B. microti infection.

Keywords: Babesia microti; Haemaphysalis longicornis; expression profiles; porin; protozoan parasite; tick.