Elevated cerebrospinal fluid kynurenic acid levels in patients with tick-borne encephalitis.

BACKGROUND: Kynurenic acid (KYNA) is a neuroactive metabolite of tryptophan that is thought to regulate cognitive functions. Previous studies have shown that levels of KYNA increase during virus infection and that this metabolite interacts with the immune system. OBJECTIVE: The aim of the study was to investigate whether patients with tick-borne encephalitis (TBE), a viral infectious disease associated with long-term cognitive impairment, have increased levels of KYNA in the cerebrospinal fluid (CSF). METHODS: CSF KYNA was analysed using high-performance liquid chromatography in 108 patients with TBE and 52 age-matched controls. Patients were classified according to the severity of TBE: mild (47%), moderate (44%) or severe (9%). RESULTS: Concentrations of CSF KYNA were considerably higher in patients with TBE (5.3 nmol L(-1) ) than in control subjects (0.99 nmol L(-1) ). KYNA concentration in the CSF varied greatly amongst individuals with TBE and increased (P < 0.05) with the severity of disease. CONCLUSIONS: This is the first study to demonstrate increased levels of CSF KYNA in patients with TBE. The importance of brain KYNA in both immune modulation and neurotransmission raises the possibility that abnormal levels of the compound in TBE might play a part in the pathophysiology of the disease. A detailed knowledge of endogenous brain KYNA during the course of CNS infection might yield further insights into the neuroimmunological role of the compound and may also provide new pharmacological approaches for the treatment of cognitive symptoms.

Molecular characterisation of two mumps virus genotypes circulating during an epidemic in Lithuania from 1998 to 2000.

An epidemic of mumps in Lithuania started in December 1998 and continued until May 2000. The total registered number of cases was about 11.000 of a total of 3,7 million inhabitants in Lithuania (29,7 cases/10,000). Virus-containing samples were collected from 80 patients treated at the hospital of Kaunas from October 1999 until the end of the epidemic. Out of the 80 patients with parotitis, meningitis was observed in 11 patients and orchitis in 22 of 69 male patients. Twenty-seven virus strains were genotyped by nucleotide sequencing of the small hydrophobic (SH) protein gene, and the 57 amino acid sequences of the gene were deduced. Twenty-five virus strains belonged to the C genotype and two were of the D genotype. By phylogenetic analysis the virus strains causing meningitis grouped in a separate cluster, designated C1, within the C genotype. Another group of ten of the 25 genotype C strains exhibited an amino acid triplet at amino acid positions 28 to 30 of the protein, consisting of valine, alanine and serine, instead of the previously recognised valine, valine and serine combination of genotype C. The amino acid alanine at position 29 was found in combination with the amino acid serine at position 48. This variant was designated C2 and it was associated with parotitis. The amino acid alanine at position 29 and serine in position 48 of the C2 genotype may constitute a marker of low neurovirulence compared to other genotype C strains.

Tick-borne encephalitis virus in Lithuania.

Tick-borne encephalitis (TBE) is a severe problem in Lithuania, indicated by the 171 to 645 serologically confirmed cases that occurred each year between 1993 and 1999. In the present report, the first isolation and partial genetic analysis of a Lithuanian TBE virus (TBEV) strain isolated from a patient's serum sample is described. The patient was bitten by a tick while visiting the Lazdijai district (Veisiejai forest) in the southernmost part of Lithuania, a geographical area where Ixodes ricinus but not Ixodes persulcatus ticks are known to be present. The E protein-encoding viral gene sequence (nt 74-1273) recovered from the TBEV isolate showed the closest similarity to previously characterized European strains of the Western TBEV subtype, including the prototype TBEV strain Neudoerfl and those from neighbouring Latvia. Accordingly, the Lithuanian isolate was placed within the Western genetic lineage of TBEV in phylogenetic trees.