Borrelia miyamotoi infection leads to cross-reactive antibodies to the C6 peptide in mice and men.

OBJECTIVES: Borrelia miyamotoi is a relapsing fever Borrelia, transmitted by hard (Ixodes) ticks, which are also the main vector for Borrelia burgdorferi. A widely used test for serodiagnosis of Lyme borreliosis is an enzyme immunoassay (EIA) based on the C6 peptide of the B. burgdorferi sl VlsE protein. We set out to study C6 reactivity upon infection with B. miyamotoi in a large well-characterized set of B. miyamotoi disease (BMD) patient sera and in experimental murine infection. METHODS: We performed in silico analyses, comparing the C6-peptide to immunodominant B. miyamotoi variable large proteins (Vlps). Next, we determined C6 reactivity in sera from mice infected with B. miyamotoi and in a unique longitudinal set of 191 sera from 46 BMD patients. RESULTS: In silico analyses revealed similarity of the C6 peptide to domains within B. miyamotoi Vlps. Cross-reactivity against the C6 peptide was confirmed in 21 out of 24 mice experimentally infected with B. miyamotoi. Moreover, 35 out of 46 BMD patients had a C6 EIA Lyme index higher than 1.1 (positive). Interestingly, 27 out of 37 patients with a C6 EIA Lyme index higher than 0.9 (equivocal) were negative when tested for specific B. burgdorferi sl antibodies using a commercially available immunoblot. CONCLUSIONS: We show that infection with B. miyamotoi leads to cross-reactive antibodies to the C6 peptide. Since BMD and Lyme borreliosis are found in the same geographical locations, caution should be used when relying solely on C6 reactivity testing. We propose that a positive C6 EIA with negative immunoblot, especially in patients with fever several weeks after a tick bite, warrants further testing for B. miyamotoi.

[ELISA and PCR test systems used to detect Crimean-Congo hemorrhagic fever virus].

Studying the sensitivity and specificity of enzyme-linked immunosorbent assay (ELISA) for the indication of Crimean-Congo hemorrhagic fever (CCHF) virus antigens and those of reverse transcription and polymerase chain reaction (RT-PCR) for the detection of CCHF virus RNA, and those of a intercerebral infection method in newborn albino mice systems for the determination of viral infectious activity established that the sensitivity of ELISA was 1-2 orders of magnitude less than that of RP-PCR. The latter proved to be better in studying the sera sampled from patients with CCHF. The results of studying the samples of H. marginatum ticks, the CCHF virus vectors by ELISA and RT-PCR were similar.

[Comparative analysis of virulence of the Siberian and Far-East subtypes of the tick-born encephalitis virus]. / Sravnitel'nyi analiz virulentnosti sibirskogo i dal'nevostochnogo podtipov virusa kleshchevogo entsefalita.

The Siberian subtype of the tick-borne encephalitis virus (TEV) is different from the Far-East subtype by a moderate virulence observed in Siberian hamsters and by a low infection development rate (100 strains were compared). No differences were found in neuro-invasiveness. Clinical findings and experiments with monkeys denote the ability of the Siberian subtype to provoke severe forms of tick-borne encephalitis (TBE). The inflammation-and-degenerative changes were localized in the brain cortex, subcortical ganglions, nuclei of medulla oblongata, in the cortex and nuclei of the cerebellum as well as in the anterior horns of the spinal cord. 18 disease cases triggered by the Siberian TEV subtypes in residents of the Western and Eastern Siberia and of Central Russia (Yaroslavl Region), including 7 acute TBE cases (5 lethal outcomes), as well as 11 chronic TBE cases are analyzed. The viral RNA was found in the cortex, medulla oblongata, horn and in the cervical part of the spinal cord of those diseased of acute TBE. Sequences of genotyped strains were presented to Gen Bank, NCBI (AY363846-AY363865).

[The Siberian and Far-Eastern subtypes of tick-borne encephalitis virus registered in Russia's Asian regions: genetic and antigen characteristics of the strains]. / Sibirskii i dal'nevostochnyi podtipy virusa kleshevogo éntsefalita v evropeiskikh i aziatskikh regionakh Rossii: geneticheskaia i antigennaia kharakteristika shtammov.

Agar gel precipitation test with cross-adsorbed immune sera was used for the antigenic differentiation of strains of tick-borne encephalitis virus (TBEV). Fifty strains of the Far East TBEV serotype and 46 strains of the Siberian (Aina) TBEV serotype were isolated from Ixodes persulcatus, which is the main vector of the above TBEV subtypes in the Asian and European parts of Russia. The fragment of the envelope protein gene was sequenced for TBEV strains. Sequences of new-group strains of the Siberian subtypes isolated from 3 patients with chronic TBE and from brain tissues of 4 deceased patients were determined. Lethal TBE outcomes were registered in Siberia (Irkutsk Region and Krasnoyarsk Territory) and in Russia's European part (Yaroslavl Region).

[Multilocus sequence-typing for characterization of Moscow strains of Haemophilus influenzae type b]. / Kharakteristika moskovskikh shtammov Haemophilus influenzae tipa b metodom mul'tilokusnogo sekvenirovaniia-tipirovaniia.

Haemophilius influenzae, type b (Hib) bacteria, were genotyped by multilocus sequence typing (MLST) using 5 loci (adk, fucK, mdh, pgi, recA). 42 Moscow Hib strains (including 38 isolates form cerebrospinal fluid of children, who had purulent meningitis in 1999-2001, and 4 strains isolated from healthy carriers of Hib), as well as 2 strains from Yekaterinburg were studied. In MLST a strain is characterized, by alleles and their combinations (an allele profile) referred to also as sequence-type (ST). 9 Sts were identified within the Russian Hib bacteria: ST-1 was found in 25 strains (57%), ST-12 was found in 8 strains (18%), ST-11 was found in 4 strains (9%) and ST-15 was found in 2 strains (4.5%); all other STs strains (13, 14, 16, 17, 51) were found in isolated cases (2.3%). A comparison of allelic profiles and of nucleotide sequences showed that 93% of Russian isolates, i.e. strain with ST-1, 11, 12, 13, 15 and 17, belong to one and the same clonal complex. 2 isolates from Norway and Sweden from among 7 foreign Hib strains studied up to now can be described as belonging to the same clonal complex; 5 Hib strains were different from the Russian ones.

[Dynamics of initial L-cell adhesion. I. The effect of serum and albumin]. / Dinamika nachal'nogo prikrepleniia L-kletok. I. Vliianie syvorotki i al'bumina.

The adhesion of neoplastic mouse fibroblasts of line L was investigated during the formation of initial cell-substrate contact after the settling of spherical cells from suspension. nu (t), part of cell population which remained attached to the substrate after the impulse action of detaching force in the moment t, is used as a quantitative measure of the initial attachment process. The effects of the detaching force value and of the experimental medium composition on the main parameters of sigmoidal function nu (t) are studied. It is shown that 1) with the change of the detachment force three main parameters of function nu (t) are changed; 2) with the increase of the concentration of serum added in the Eagle medium the cell attachment becomes monotonely weaker and slower; albumin has the similar effect.