Quantitations of Borrelia and Bartonella DNA and tick-borne encephalitis virus RNA in Ixodes persulcatus ticks collected in Chelyabinsk region

Distribution and Characterisation of Tick-Borne Flavi-, Flavi-like, and Phenuiviruses in the Chelyabinsk Region of Russia

In this work, we presented data from a two-year study of flavi-, flavi-like, and phenuiviruses circulation in the population of ixodid ticks in the Chelyabinsk region. We isolated three tick-borne encephalitis virus (TBEV) strains from I. persulcatus, which was not detected in the ticks of the genus Dermacentor. The virus prevalence ranged from 0.66% to 2.28%. The Yanggou tick virus (YGTV) is widespread in steppe and forest-steppe zones and is mainly associated with ticks of the genus Dermacentor. We isolated 26 strains from D. reticulatus, D. marginatus, and I. persulcatus ticks in the HAE/CTVM8 tick cell line. The virus prevalence ranged from 1.58% to 4.18% in D. reticulatus, ranged from 0.78% to 3.93% in D. marginatus, and was 0.66% in I. persulcatus. There was combined focus of TBEV and YGTV in the territory of the Chelyabinsk region. The Alongshan virus (ALSV) was found to be associated with I. persulcatus ticks and is spread in forest zone. We detected 12 amplicons and isolated 7 strains of ALSV in tick cells. The virus prevalence ranged from 1.13% to 6.00%. The phlebovirus Gomselga and unclassified phenuivirus Stavropol were associated with I. persulcatus and D. reticulatus ticks, respectively. Virus prevalence of the unclassified phenuivirus Stavropol in the Chelyabinsk region is lower than that in neighbouring regions.

Co-infections with multiple pathogens in natural populations of Ixodes persulcatus ticks in Mongolia

Background

In Mongolia, the taiga tick Ixodes persulcatus is the major vector of tick-borne pathogens. Knowledge about co-infections of these pathogens in ticks is necessary both for understanding their persistence in nature and for diagnosing and treating tick-borne diseases.

Methods

The prevalence of seven tick-borne infections in 346 I. persulcatus collected from the Selenge and Bulgan provinces of Mongolia was evaluated using real-time PCR. Quantification of Borrelia spp. was performed using multiplex quantitative PCR targeting the 16S rRNA gene. Genetic analysis of Borrelia spp. in 11 ticks infected with Borrelia miyamotoi, including six ticks co-infected with Borrelia burgdorferi sensu lato (s.l.), was performed by high-throughput sequencing of the flaB gene fragment.

Results

Six ticks (1.7%) were infected with tick-borne encephalitis virus (TBEV); 171 (49.4%), with B. burgdorferi sensu lato; 17 (4.9%), with B. miyamotoi; 47 (13.6%), with Anaplasma phagocytophilum; and 56 (16.2%), with Ehrlichia sp. Neither Rickettsia sibirica nor R. heilongjiangensis were detected. Borrelia burgdorferi s.l. occurred as co-infection in 55 (32.2%) of all infected ticks. The other pathogens co-infected ticks in 58.8–70.2% of cases. No pairwise associations between co-infecting pathogens were observed, with the exception of a positive association between A. phagocytophilum and Ehrlichia sp. infections. The spirochete loads of B. miyamotoi were significantly higher than those of B. burgdorferi s.l. (mean: 5.2 vs 4.0 log10 genome copies/tick, respectively). Ten isolates of B. miyamotoi belonged to the Siberian lineage. Borrelia burgdorferi s.l was represented by nine isolates of B. afzelii, B. bavariensis and B. garinii.

Conclusions

In populations of I. persulcatus inhabiting the Selenge and Bulgan provinces of Mongolia, five vector-borne pathogens, i.e. TBEV, B. burgdorferi s.l., B. miyamotoi, A. phagocytophilum and Ehrlichia sp., persist independently from each other, with the exception of A. phagocytophilum and Ehrlichia sp. which seem to share the circulation mode. The discrepancies in B. burgdorferi s.l. and B. miyamotoi prevalence and spirochete load per tick suggest that different ecological niches are occupied by Lyme disease and relapsing fever agents. High-throughput sequencing allows genetic identification of borreliae species in co-infected ticks.

Graphical Abstract

[Tick-borne neuroinfections: Clinical characteristics, immunopathogenesis, and new pharmacotherapeutic strategies]

AIM

To study the semiotics of neurological lesions in patients with tick-borne encephalitis, Ixodes tick-borne borreliosis (ITBB) and mixed infection (MI), their immunopathogenesis, and the possibilities of current pathogenetic pharmacological correction.

SUBJECTS AND METHODS

A total of 220 patients with tick-borne encephalitis, ITBB, and MI concurrent with the syndromes of central nervous system lesions were examined. The immunological studies encompassed the examination of mononuclear cells in the cerebrospinal fluid (CSF), the population and subpopulation composition of lymphocytes, and nitroxidergic processes in the serum and CSF from the total level of final stable nitric oxide metabolites. For pharmacotherapeutic correction, the metabolic drug cytoflavin was used as newly indicated.

RESULTS

Cytofluorometric analysis of the CSF cellular composition showed the mononuclear cell predominance of CD3+ (58.6%), CD4+ (57.2%), CD8+ (16.8%) lymphocytes and monocytes (34.4%), which expressed the phenotypic marker CD14+. This reflects the nature of a local immune response: an increase in the immunoregulatory index CD4+/CD8+ from 3.4 to 5.6, respectively, while the normal proportion of these cells in the blood ranges from 1.5 to 2.2. CSF lymphocytes were found to be ready for Fas-mediated apoptosis dependent on the receptor (CD95+ was 64.3%).There was a correlation using the pair correlation coefficient between the total concentration of the metabolites of the nitroxide molecule and the percentage of CD14+ (r=0.5; p<0.05). The paired Wilcoxon test was used to analyze serum NO2, NO3, and NOx, which revealed significant differences in nitrites [2.70 (1.90, 2.95; p=0.001)] and total NO metabolites [18.00 (18.00, 22.60; p=0.006)] and statistically significant changes in nitrates [13.29 (15.70. 20.30; p=0.075)] in patients receiving cytoflavin infusions.

CONCLUSION

The immune response of Th-1 forms between the CSF phagocytic, antigen-presenting, and immunocompetent lymphocytes in patients with tick-borne neuroinfections. The use of cytoflavin as an agent for neurotransmitter support to correct nitroxidergic processes is pathogenetically justified.