SummaryThe tick Ixodes ricinus is responsible for the transmission of a number of bacterial, protozoan and viral diseases to humans and animals in Europe and š Č ȇ Northern Africa. Female I. ricinus from England, Switzerland and Italy have been found to harbour an intracellular a-proteobacterium, designated IricES1, within the cells of the ovary. IricES1 is the only prokaryote known to exist within the mitochondria of any animal or multicellular organism. To further examine the distribution, prevalence and mode of transmission of IricES1, we performed polymerase chain reaction screening of I. ricinus adults from 12 countries across its geographic distribution, including tick colonies that have been maintained in the laboratory for varying periods of time. IricES1 was detected in 100% of field-collected female ticks from all countries examined (n = 128), while 44% of males were found to be infected (n = 108). Those males that are infected appear to harbour fewer bacteria than females. Sequencing of fragments of the 16S rRNA and gyrB genes revealed very low nucleotide diversity among various populations of IricES1. Transmission of IricES1 from engorged adult females to eggs was found to be 100% (n = 31). In tick colonies that had been maintained in the laboratory for several years, a relatively low prevalence was found in females (32%; n = 25). To our knowledge, IricES1 is the most widespread and highly prevalent of any tick-associated symbiont.

M-protein from influenza virus vaccine was purified by sodium dodecyl sulfategel chromatography and incorporated into liposomes by solubilization with octylglucoside and subsequent dialysis. Liposomes containing M-protein formed a distinct population with a density of 1.22 g/ml on sucrose-gradient centrifugation, regardless of the net charge on the liposomes. Treatment of the liposomes by freeze-fracture followed by electron microscopic examination showed multilamellar structures in those liposomes without M-protein; liposomes containing Mprotein were mulberry-like structures which appeared unilamellar. These studies show incorporation of M-protein into the lipid bilayer.

No abstract

No abstract

No abstract

No abstract

A highly virulent mouse-adapted variant of influenza virus A/Aichi/2/68 (H3N2) was crossed either with the original A/USSR/90/77 (H1N1) influenza virus strain or with its mouse-adapted, moderately mouse virulent variant. The reassortants were characterized with respect to their genetic content and pneumovirulence for mice. The reassortants fell into three categories: avirulent, highly virulent (resembling in this respect the parent A/Aichi/2/68 virus) and moderately virulent (resembling the mouse-adapted A/USSR/90/77 parent virus). The analysis of the parental origin of the genes of 6 reassortants allowed to suggest that changes in the HA gene and in a polymerase gene (most likely, PB1) were necessary for the acquisition of virulence by the A/USSR/90/77 virus in the course of adaptation to mice, whereas the changes in two other polymerase genes as well as in the genes NA and NS were not involved. The low degree of pathogenicity characteristic of the mouse-adapted A/USSR/90/77 virus was determined by gene(s) other than HA.

Human granulocytic anaplasmosis (HGA) and Lyme borreliosis (LB) are tick-borne infectious diseases caused by Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato species, respectively. In this study, p44/msp2 paralogues specific to A. phagocytophilum and 5S-23S rRNA gene-intergenic spacers specific to B. burgdorferi sensu lato species were detected by PCR in ticks collected in two regions, Tver (Kalinin) and Konakovo, of the Tver (Kalinin) Province located 150 km north-west of Moscow. The PCR amplicons obtained were further characterized by sequencing and RFLP analysis. In the total of 199 ticks collected, 8.8 % (7/80) and 33.8 % (27/80) of Ixodes ricinus, and 2.5 % (3/119) and 45.4 % (54/119) of Ixodes persulcatus, were found to be infected with A. phagocytophilum and B. burgdorferi sensu lato spp., respectively. Of those 199 ticks, 5 (2.5 %) were coinfected with A. phagocytophilum and Borrelia afzelii. Phylogenetic analysis revealed unique p44/msp2 paralogous genes in A. phagocytophiluminfected Russian ticks. The sequence similarities with those of A. phagocytophilum in the United States, UK and Japan ranged from 42 % to 80.4 %, and there were no sequences showing more than 90 % similarity with those sequences from the other countries. The results showed that the p44/msp2 sequence similarity groups may provide an index of adaptation of A. phagocytophilum strains to specific vector ticks or reservoir hosts in different countries and areas. These findings suggest that there is a public health threat from HGA and LB in Tver Province surrounding Moscow. INTRODUCTIONHuman granulocytic anaplasmosis (HGA) and Lyme borreliosis (LB) are tick-borne and emerging infectious diseases caused by Anaplasma phagocytophilum (formerly Ehrlichia phagocytophila, revised by Dumler et al., 2001) and Borrelia burgdorferi sensu lato species. HGA is a febrile systemic illness and the severity of this disease ranges from asymptomatic seroconversion to death. The first case of human infection by A. phagocytophilum was found in the United States in 1994 (Chen et al., 1994). Since then, the number of patients has increased in the United States (Dumler et al., 2005). In Europe, the first human cases of this disease were described in 1997 (Petrovec et al., 1997), and serological and PCR analyses suggest that A. phagocytophilum is distributed throughout Europe and in some parts of the Middle East and Asia (Blanco & Oteo, 2002;Cao et al., 2000; Heo et al., 2002;Keysary et al., 1999). LB is the most common tick-borne infectious disease in the Northern Hemisphere (Masuzawa, 2004;Steere, 2001 METHODSSurvey area and tick sampling. During the summer of 2002, unfed adult ticks (I. persulcatus and I. ricinus) were collected from vegetation by a dragging method using 1 m 2 flannel flags, in the Tver (Kalinin) and Konakovo regions of the Tver Province, which are located 110-150 km north-west from Moscow. Vegetation in the survey area consists of Russian plain and forest (aspen, firs and birches) with bushes. The areas are mostly forest with l...