WEB of Laboratory of Molecular Biology of Vectors and Parasites
Our group studies molecular and cellular factors involved in the mechanism of pathogen transmission by ticks. Lyme borreliosis spirochetes, as well as tick-borne encephalitis virus, are the main focus of research, with respect to protein-carbohydrate interactions, and their interaction with the inner environment of tick Ixodes ricinus. Molecular ecology of Lyme borreliosis and tick-borne encephalitis, including modern techniques of pathogen diagnosis, has been elaborated.
Růžek D., Yakimenko V.V., Karan L.S., Tkachev S.E. (2010) Omsk haemorrhagic fever. The Lancet 376: 2104–2113.
HAJDUŠEK O., SOJKA D., KOPÁČEK P., BUREŠOVÁ V., FRANTA Z., ŠAUMAN I., WINZERLING J., GRUBHOFFER L. (2009) Knockdown of proteins involved in iron metabolism limits tick reproduction and development. Proceedings of the National Academy of Sciences 109: 1033-1038.
RUDENKO N., GOLOVCHENKO M., GRUBHOFFER L., OLIVER J.H. Jr. (2009) Borrelia carolinensis sp. nov. – a new (14th) member of Borrelia burgdorferi sensu lato complex from the southeastern United States. Journal of Clinical Microbiology 47: 134-141.
Ixoderin A (IxoA) and Chitinase 1 (Chix1) are sugar-binding proteins with putative roles in the arthropod immune system. cDNA sequence of Ixo-A indicated that the protein contains a single fibrinogen-related domain (FReD), and is related to Ornithodoros moubata and Tachypleus tridentatus lectins Dorin M and Tachylectin 5A. Ixo-A mRNA and protein expression were observed in all studied tick tissues. In addition, Ixo-A tissue specific molecules were localized in extra-cellular trachea and salivary gland matrixes of engorged ticks. For Chix1, one Glyco-18 chitinase-specific domain has been found in the cDNA sequence. Recombinant Chix1 is functional and cleaves chitin at an optimal pH. Chix1 is expressed in all studied tissues and it is confined to spots inside gut and salivary gland cells.
A defensin-like gene encoding a pro-peptide with six cysteins (Cys) was strongly induced in the Ixodes ricinus midgut after infection with borrelia spirochetes (AY335442). The gene shows high similarity to several defensin family members, with the highest similarity with the defensin-like peptides of Dermacentor variabilis. Complete sequence of the second defensin from I. ricinus expressed within the salivary glands was also reported (AAT46066). It contains four of the six essential C residues and is rather different from the previous defensin in nucleotide and amino acid sequences. There are at least two defensins present within the innate immune system of I. ricinus, that may be involved in mechanism of borrelia spirochetes transmission.
The presence of sialylated glycoconjugates in salivary glands of females Ixodes ricinus was reported. Affinity labelling of ultrathin sections with two sialic-acid specific lectins MAA II and SNA, and lectin binding analyses of blots of SDS gels, showed that MAA II and SNA lectins recognized several glycoproteins and both lectins had to each other different labelling pattern. Colorimetric quantification by the periodic acid-thiobarbituric acid test showed that salivary gland extract (SGE) from partially engorged tick females contained about 13 nmol/mg of sialic acid.
A virulent temperature-resistant variant of ts263 isolate of tick-borne encephalitis virus was identified in the quasispecies of the attenuated strain. This variant showed a high degree of neuroinvasiveness and formed large plaques in cell culture. The pathogenesis of infections caused by the parental strain and the temperature-resistant variant was completely different. Comparison of complete sequences revealed two differences in the deduced amino acid sequence of nonstructural proteins NS2B and NS3, and a long deletion within the variable segment of the 3´ NCR, but with no effect on the 3’ conserved region. These two amino acid substitutions are potential molecular determinants of the attenuated temperature-sensitive phenotype of the strain 263.
Pro porovnávací studie jsou helmintologům z různých zemí k dispozici rozsáhlé sbírky...
