PECULIARITIES OF CADMIUM-TOLERANT POPULATIONS OF IXODES TICKS: SPECIFICITY OF THEIR MICROBIOCENOSES, IMMUNITY AND VECTOR CAPACITY

About authors:

A. N. Alekseev, Zoological Institute, Russian Academy of Sciences, Universitetskaya emb., 1, 199034 St. Petersburg,
RUSSIA
H. V. Dubinina, Zoological Institute of the Russian Academy of Sciences, Universitetskaya Emb. 1, 199034 Saint Petersburg, Russia

P. A. Chirov, Saratov State University, 410026 Saratov, Russia
А. М Peterson, Saratov State University, 410026 Saratov, Russia
М. A. Turtseva, Saratov State University, 410026 Saratov, Russia

Acknowledgments:

This study was financially supported in part by a grant of the Russian Foundation for Basic Re-search (No. 04-04-49119), in part by a grant of Russian Academy of Sciences Presidium Pro-gramme «Fundamental Sciences for Medicine" (2005). We would like to thank Sergei Golovatch, who corrected the English of an advanced draft.

Annotation:

The appearance and prevalence of exoskeleton anomalies in Ixodes ticks chosen as markers of anthropogenic press allows to reveal their distribu-tion and the rate of occurrence in Russia and several Western European countries. Chemical analyses show the appearance of anomalies as being related to the accumulation of heavy metal ions, first of all cadmium which prevails in specimens and is known as changing tick metabolism. Cd concentrations are 1.5-2 times higher in anomalous ticks than in normal ones, cadmium supposedly suppressing tick immunity. To provide indirect evidence of this, microflora of anomalous and normal ticks has been compared, with 73 hungry tick females collected in April 2003 and 2004 in a focus of tick-borne diseases near St. Petersburg, Russia screened micro-biologically. A study of "vulgar" microflora in both parts of the Ixodes persulcatus Schulze population shows the whole microbiocenosis of anomalous and normal ticks as being quite different. Microflo-ra of Gram-negative and Gram-positive bacteria, bacilli, cocci and fungi appears to be much richer in anomalous ticks than in normal ones (47 versus 28 species). Only 14 (of 61) species representing the "vulgar" microflora are coincided in both groups of ticks. Not more than 4 species of microorganisms are present per normal tick, whereas one tick with exoskeleton anomalies can contain 5, 6 or even 7 species simultaneously. Only in anomalous ticks do the cocci of the genus Staphylococcus and the

 

 

 

 

 

fungi of the genus Penicillum absolutely prevail. Staphylococci are known as active stimulants of lysozyme and defensin production, both the main tools of the tick immune system. Scarcity of these cocci and fungi in normal ticks and their abundance in anomalous ones, as well as the great prevalence of multi infections in anomalous ticks are accepted as markers of their immune system suppression. Revised (6,169 adult ticks screened using PCR; 1996-2000) data concerning the prevalence of tick-borne multi infections (such as mixtures of Borre-lia, Ehrlichia, Anaplasma, Babesia or tick-borne encephalitis virus) confirm that exoskeleton anom-alies represent external markers of cadmium accu-mulation, increased tick vector capacity and dan-gerousness. Analysis of anomalous tick microflora supports this observation as well, because only among anomalous tick numerous phyto- or zoo-pathogenic bacteria and, especially, fungi have been revealed, which can be very dangerous for man with an immune system suppressed by any factor or associated disease.

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