Salivary scavenger receptor cysteine-rich protein gp340 aggregates streptococci and other bacteria as part of the host innate defense system at mucosal surfaces. In this article, we have investigated the properties of fluid-phase gp340 and hydroxylapatite surface-adsorbed gp340 in aggregation and adherence, respectively, of viridans group streptococci (e.g., Streptococcus gordonii and Streptococcus mutans), non-viridans group streptococci (e.g., Streptococcus pyogenes and Streptococcus suis), and oral Actinomyces. Fluid-phase gp340 and surface-phase gp340 bioforms were differentially recognized by streptococci, which formed three phenotypic groupings according to their modes of interaction with gp340. Group I streptococci were aggregated by and adhered to gp340, and group II streptococci preferentially adhered to surface-bound gp340, while group III streptococci were preferentially aggregated by gp340. Each species of Streptococcus tested was found to contain strains representative of at least two of these gp340 interaction groupings. The gp340 interaction modes I to III and sugar specificities of gp340 binding strains coincided for several species. Many gp340 interactions were sialidase sensitive, and each of the interaction modes (I to III) for S. gordonii was correlated with a variant of sialic acid specificity. Adherence of S. gordonii DL1 (Challis) to surface-bound gp340 was dependent upon expression of the sialic acid binding adhesin Hsa. However, aggregation of cells by fluid-phase gp340 was independent of Hsa and involved SspA and SspB (antigen I/II family) polypeptides. Conversely, both gp340-mediated aggregation and adherence of S. mutans NG8 involved antigen I/II polypeptide. Deletion of the mga virulence regulator gene in S. pyogenes resulted in increased cell aggregation by gp340. These results suggest that salivary gp340 recognizes different bacterial receptors according to whether gp340 is present in the fluid phase or surface bound. This phase-associated differential recognition by gp340 of streptococcal species of different levels of virulence and diverse origins may mediate alternative host responses to commensal or pathogenic bacterial phenotypes.

A national crowdsourcing-based tick collection campaign was organized in 2015 with the objective of producing novel data on tick distribution and tick-borne pathogens in Finland. Nearly 20 000 Ixodes ticks were collected. The collected material revealed the nationwide distribution of I. persulcatus for the first time and a shift northwards in the distribution of I. ricinus in Finland. A subset of 2038 tick samples containing both species was screened for Borrelia burgdorferi sensu lato (the prevalence was 14.2% for I. ricinus and 19.8% for I. persulcatus), B. miyamotoi (0.2% and 0.4%, respectively) and tick-borne encephalitis virus (TBEV; 0.2% and 3.0%, respectively). We also report new risk areas for TBEV in Finland and, for the first time, the presence of B. miyamotoi in ticks from mainland Finland. Most importantly, our study demonstrates the overwhelming power of citizen science in accomplishing a collection effort that would have been impossible with the scientific community alone.

BackgroundLaboratory diagnosis of Lyme neuroborreliosis (LNB) is partly based on the detection of intrathecal Borrelia burgdorferi–specific antibody production (increased antibody index (AI)). However, AI can be negative in patients with early LNB and, conversely, can remain elevated for months after antibiotic treatment. Recent studies suggested that the chemokine CXCL13 in the cerebrospinal fluid (CSF) is a biomarker for active LNB. Also, CSF neopterin-level determination has been used to assess the degree of neuroinflammation in a wide variety of diseases.MethodsCXCL13 concentrations were analyzed in CSF samples of 366 retrospectively identified individuals. The samples represented pretreatment LNB (38 patients), non-LNB comparison patients, tick-borne encephalitis, central nervous system (CNS) varicella zoster virus infection, CNS herpes simplex virus infection, CNS HHV6 infection, CNS enterovirus infection, and untreated neurosyphilis. The panel included also samples from patients with multiple sclerosis and other neuroinflammatory conditions. Of the LNB patients, 24 posttreatment CSF samples were available for CXCL13 analysis. Neopterin concentrations were determined in a subset of these samples.ResultsThe CXCL13 concentrations in CSF samples of untreated LNB patients were significantly higher (median, 6,480 pg/ml) than the concentrations in the non-LNB group (median, <7.8 pg/ml), viral CNS infection samples (median, <7.8 pg/ml), or samples from patients with noninfectious neuroinflammatory conditions (median, <7.8 pg/ml). The use of cut-off 415 pg/ml led to a sensitivity of 100% and specificity of 99.7% for the diagnosis of LNB in these samples. CSF CXCL13 median concentrations declined significantly from 16,770 pg/ml before to 109 pg/ml after the treatment.CSF neopterin concentration was significantly higher among the untreated LNB patients than in the non-LNB group. The use of neopterin concentration 10.6 nM as the cut-off led to a sensitivity of 88.6% and a specificity of 65.0% for the diagnosis of LNB. The CSF neopterin concentrations decreased statistically significantly with the treatment.ConclusionsThese results clearly indicate that highly elevated CSF CXCL13 levels are strongly associated with untreated LNB. CXCL13 outperformed neopterin and appears to be an excellent biomarker in differentiating LNB from viral CNS infections and from other neuroinflammatory conditions.

We investigated the epidemiology of Lyme borreliosis (LB) in Finland for the period 1995–2014 by using data from 3 different healthcare registers. We reviewed data on disseminated LB cases from the National Infectious Diseases Register (21,051 cases) and the National Hospital Discharge Register (10,402 cases) and data on primary LB (erythema migrans) cases from the Register for Primary Health Care Visits (11,793 cases). Incidence of microbiologically confirmed disseminated LB cases increased from 7/100,000 population in 1995 to 31/100,000 in 2014. Incidence of primary LB cases increased from 44/100,000 in 2011 to 61/100,000 in 2014. Overall, cases occurred predominantly in women, and we observed a bimodal age distribution in all 3 registers. Our results clearly demonstrate that the geographic distribution of LB has expanded in Finland and underscore the importance of LB as an increasing public health concern in Finland and in northern Europe in general.

BackgroundAlmost 3500 tick samples, originally collected via a nationwide citizen science campaign in 2015, were screened to reveal the prevalence and distribution of a wide spectrum of established and putative tick-borne pathogens vectored by Ixodes ricinus and I. persulcatus in Finland. The unique geographical distribution of these two tick species in Finland allowed us to compare pathogen occurrence between an I. ricinus-dominated area (southern Finland), an I. persulcatus-dominated area (northern Finland), and a sympatric area (central Finland).ResultsOf the analysed ticks, almost 30% carried at least one pathogen and 2% carried more than one pathogen. A higher overall prevalence of tick-borne pathogens was observed in I. ricinus than in I. persulcatus: 30.0% (604/2014) versus 24.0% (348/1451), respectively. In addition, I. ricinus were more frequently co-infected than I. persulcatus: 2.4% (49/2014) versus 0.8% (12/1451), respectively. Causative agents of Lyme borreliosis, i.e. bacterial genospecies in Borrelia burgdorferi (sensu lato) group, were the most prevalent pathogens (overall 17%). “Candidatus Rickettsia tarasevichiae” was found for the first time in I. ricinus ticks and in Finnish ticks in general. Moreover, Babesia divergens, B. venatorum and “Candidatus Neoehrlichia mikurensis” were reported for the first time from the Finnish mainland.ConclusionsThe present study provides valuable information on the prevalence and geographical distribution of various tick-borne pathogens in I. ricinus and I. persulcatus ticks in Finland. Moreover, this comprehensive subset of ticks revealed the presence of rare and potentially dangerous pathogens. The highest prevalence of infected ticks was in the I. ricinus-dominated area in southern Finland, while the prevalence was essentially equal in sympatric and I. persulcatus-dominated areas. However, the highest infection rates for both species were in areas of their dominance, either in south or north Finland.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3131-y) contains supplementary material, which is available to authorized users.