Molecular Analysis of Calreticulin Expressed in Salivary Glands of Rhipicephalus (Boophilus) microplus Indigenous to Thailand

Abstract

The tropical cattle tick, Rhipicephalus (Boophilus) microplus, is an important ectoparasite of livestock in Thailand that causes economic losses due to the direct effects of tick feeding and by the pathogens they transmit. Intensive acaricide use has several drawbacks, which spurred efforts to develop anti-tick vaccines. Vaccines targeting concealed antigens localized in the tick midgut result in reduced tick fecundity, but molecules localized in the tick salivary glands, which could play a role in pathogen transmission, remain largely unexplored for R. microplus. Calreticulin (CRT) is a protein found in tick salivary glands and saliva, and CRT might facilitate tick feeding and pathogen transmission through anti-thrombotic and complement-inhibition activities. This then suggests that CRT should be evaluated as a vaccine candidate antigen to control cattle ticks in Thailand. The objective of this work was to clone, sequence, and analyze cDNA encoding CRT from salivary glands of R. microplus indigenous to Thailand. Nucleotide sequence analysis showed an open reading frame of 1233 bp. Comparison of the amino acid sequence showed 65-99% identities to other known CRTs from Oryctolagus cuniculus, Rattus norvegicus, Homo sapiens, Bos taurus, R. sanguineus, and R. microplus. The N- and P-domains of CRT were the most conserved, whereas the C-domain was high acid and more variable. CRT primary sequences were most conserved among mammals. Further investigations are warranted to determine whether immunization with Thai B. microplus CRT can affect tick performances and experimental pathogen transmission.

Deorphanization and target validation of cross-tick species conserved novel Amblyomma americanum tick saliva protein

“…The specificity of Abs to both 24 h and 48 h TSPs as well as the reactivity of mono-specific Abs to r Aam AV422 on western blots of r Aam AV422, tick saliva, haemolymph and dissected tick organs led us to conclude that this protein was ubiquitously expressed and injected into the host within 24 h of tick feeding. In the literature two other cross-tick species conserved TSPs, tick calreticulin (Sanders et al, 1998, 1999; Ferreira et al, 2002; Xu et al, 2004, 2005; Alarcon-Chaidez et al, 2006; Gao et al, 2008; Kaewhom et al, 2008; Parizi et al, 2009) and histamine release factor (Mulenga et al, 2003a Mulenga and Azad, 2005; Dai et al, 2010) have been described. A common feature between tick calreticulin and histamine release factor is that they both have homologs in vertebrates (Mulenga et al, 2003b, Mulenga and Azad, 2005; Coe and Michalak, 2009; Martins et al, 2010).…”

Amblyomma americanum tick calreticulin binds C1q but does not inhibit activation of the classical complement cascade

“…Coding cDNAs have now been identified in multiple organisms including ticks (Jaworski et al, 1995, Ferreira et al, 2002, Xu et al, 2004, 2005, Kaewhom et al, 2008, Gao et al, 2008), fleas (Jaworski et al, 1996), nematodes (Smith, 1992, Huggins et al, 1995, Tsuji et al, 1998, Scott et al, 1999, Mendlovic et al, 2004, Cabezón et al, 2008, Li et al, 2011), protozoan parasites (Aguillón et al, 2000, Marcelain et al, 2000, González et al, 2002), fish (Kales et al, 2004, Bai et al, 2012) and plants (Jia et al, 2008, Jin et al, 2009, An et al, 2011). Many more CRT sequences have been deposited in GenBank unpublished as direct submissions.…”

De novo sequencing, assembly and analysis of salivary gland transcriptome of Haemaphysalis flava and identification of sialoprotein genes

“…Like other blood feeders, ticks produce various 352 secreted proteins to participate in the digestion of the host blood 353 meal or to modulate host defenses in order to maintain their blood 354 feeding capacity. Among these modulatory molecules, cysteine 355 (Yamaji et al, 2013), longipain (Tsuji et al, 2008), 4D8 (de la 356 Fuente et al, 2006), calreticulin (Kaewhom et al, 2008), metallo-357 proteases (Ali et al, 2014), serine protease inhibitor (Tirloni 358 et al, 2014), enolase (Díaz-Martín et al, 2013), heat shock proteins 359 (Tian et al, 2011) and AV422 (Mulenga et al, 2013) (Fig. S1).…”