Rhipicephalus microplus cystatin as a potential cross-protective tick vaccine against Rhipicephalus appendiculatus

Author(s):Show less -

Parizi, Luis Fernando ^[1] ; Rangel, Carolina Konrdorfer ^[1] ; Sabadin, Gabriela Alves ^[1] ; Saggin, Bianca Fagundes ^[1] ; Kiio, Irene ^{[2, 3]} ; Xavier, Marina Amaral ^[1] ; Matos, Renata da Silva ^[4] ; Camargo-Mathias, Maria Izabel ^[4] ; Seixas, Adriana ^{[5, 6]} ; Konnai, Satoru ^[7] ; Ohashi, Kazuhiko ^[7] ; Githaka, Naftaly Wang'ombe ^[2] ; Vaz Jr, Itabajara da Silva

Affiliation

^[1] Univ Fed Rio Grande do Sul, Ctr Biotecnol, Ave Bento Goncalves 9500, BR-91501970 Porto Alegre, RS - Brazil

^[2] ILRI, POB 30709-00100, Nairobi - Kenya

^[3] Univ Nairobi, Sch Med, Dept Biochem, POB 30197-00100, Nairobi - Kenya

^[4] UNESP Univ Estadual Paulista, Inst Biociencias, Dept Biol, Rio Claro, SP - Brazil

^[5] Inst Nacl Ciencia & Tecnol Entomol Mol, Rio De Janeiro - Brazil

^[6] Univ Fed Ciencias Saude Porto Alegre, Dept Farmacociencias, Rua Sarmento Leite 245, BR-90050170 Porto Alegre, RS - Brazil

^[7] Hokkaido Univ, Grad Sch Vet Med, Dept Dis Control, Lab Infect Dis, Sapporo, Hokkaido 0600818 - Japan

• Document type: Journal article
• Source: TICKS AND TICK-BORNE DISEASES; v. 11, n. 3 MAY 2020.
• Web of Science Citations: 0

Abstract

Rhipicephalus appendiculatus, the brown ear tick, is an important disease vector of livestock in eastern, central and southern Africa. Rhipicephalus appendiculatus acaricide resistance requires the search for alternative methods for its control. Cystatins constitute a superfamily of cysteine peptidase inhibitors vital for tick blood feeding and development. These inhibitors were proposed as antigens in anti-tick vaccines. In this work, we applied structural and biochemical approaches to characterize a new cystatin named R. appendiculatus cystatin 2a (Racys2a). Structural modeling showed that this new protein possesses characteristic type 2 cystatin motifs, besides conservation of other structural patterns along the protein. Peptidase inhibitory assays with recombinant Racys2a showed modulation of tick and host cathepsins involved in blood digestion and immune system responses, respectively. A heterologous tick challenge with R. appendiculatus in rabbits immunized with recombinant Rhipicephalus microplus cystatin 2c (rBmcys2c) was performed to determine cross-reactivity. Histological staining showed that rBmcys2c vaccination caused damage to the gut, salivary gland and ovary tissues in R. appendiculatus. Furthermore, cystatin vaccine reduced the number of fully engorged adult females in 11.5 %. Consequently, strategies to increase the protection rate are necessary, including the selection of two or more antigens to compose a vaccine cocktail. (AU)

• FAPESP's process: 14/13143-7 - Study morphophysiological salivary gland, singânglio, body of ovarian gene and engorged females of R. sanguineus (Latreille, 1806) (Acari: Ixodidae) treated with different concentrations thymol
• Grantee: Renata da Silva Matos
• Support Opportunities: Scholarships in Brazil - Doctorate