High Seroprevalence of CMV Among Women of Childbearing Age Implicates High Burden of Congenital Cytomegalovirus Infection in Poland.

Cytomegaloviruses are common worldwide, with variable frequency of infections. The infection in pregnancy may lead to pregnancy loss or serious sequelae for the child. To understand the risk posed by CMV in Poland we conducted cross-sectional study on women aged 15-49 basing on existing serum bank. Age dependent incidence, the rates of congenital infection and sequelae were modelled from sero-prevalence, literature and demographic data. The overall anti-CMV IgG prevalence was 81.9% increasing from 74.3% in <30 years old to 94.3% in subjects 45+ years old. The lowest incidence was estimated at the age of 15 and the highest at the age 34 (3.8 and 8.95 respectively/100 women/year). The estimated rate of cCMV varies from 22.4 to 37.2 per 1000 live birth depending on the assumptions made. The proportion of cases due to secondary infection ranged from 34.8% to 49.9% accordingly.

[Measles virus stimulation effect on the expression of Toll-like receptors in PBMC]. / Wplyw stymulacji wirusem odry na ekspresje receptorów Toll-like w komórkach PBMC.

INTRODUCTION: Toll-like receptors (TLRs) are an important component of a innate immune system. Stimulation of TLRs, through action with helper T cells, could change Th1/Th2 balance and thus affect adaptive immune response. Receptors TLR2 and TLR4 play important role in immune response to measles virus. The aim of this work was stimulation of the peripheral blood mononuclear cells (PBMC) and determination of Toll-like gene expression in these cells. METHODS: PBMCs from 20 healthy donors were stimulated with measles viruses and ligands for TLR2 and TLR4. For examinations the real time RT-PCR (QuantiFast® Assay, Qiagen) was used. The expression of Toll-like receptors was determined on muRNA level, using real-time one step RT-PCR (QuantiFast® Assay, Qiagen) with simultaneous detection of TLR2 and TLR4 genes and housekeeping gene (GAPDH). RESULTS: Virus-specific influence of wild measles virus strains activity on PBMC derived from vaccinated seronegative individuals manifested in higher level of expression of TLR2 and TLR4 genes in compare to the expression of these genes in PBMC of seropositive individuals. CONCLUSIONS: Toll-like receptors participate in the development of immune response to measles virus.

Effect of chlorpyrifos on the profile of subpopulations immunocompetent cells B, T and NK in in vivo model.

BACKGROUND: Current studies have indicated many environmental factors, such as pesticides, that cause immune system disorders through inducing changes in humoral and cellular responses thereby increasing the risk of contracting infectious diseases and cancer. The literature suggests that low exposures to certain organophosphorus pesticides stimulate the immune system, whilst high exposures result in decreased function. Precise mechanisms for the fall in immunocompetence are often unclear, however it can be predicted that the intimate interaction between the nervous and immune systems can potentially lead to toxicity. OBJECTIVES: To determine the effects of organophosphorus pesticide, chlorpyrifos that is often used in Poland, on selected immunological responses, such as immune-competent cell proportions formed experimentally in-vivo by cells of Wistar rats during subchronic exposures after 45 and 90 days. MATERIALS AND METHODS: The test was carried out on ten male and ten female Wistar rats in each of three test groups, who received 3 chlorpyrifos doses for 90 days intragastrically, according to OECD guidelines (No. 401). Two control groups were given olive oil. After completion, the animals were deeply anaesthetised by a mixture of ketamine (Vetaketam) and xylazine (Vetaxym). Immuno-competent cells were profiled by a commercial monoclonal antibody method. In order to measure the dynamics of any changes, the aforementioned immunological responses were investigated after 45 days using the same procedures for obtaining the relevant biological test material. RESULTS: Test animals exposed to chlorpyrifos had altered number of white bood cells which were either increased or decreased relative to controls after 45 and 90 days for all exposure levels used. CONCLUSIONS: The study demonstrated changes in white-blood cell (lymphocyte) response profiles, reflecting an immunomodulation although such changes were equivocal, where both suppression and stimulation were observed. KEY WORDS: immunomodulation, immune system, lymphocyte, organophosphorus pesticides, chlorpyrifos.

The significance for epidemiological studies anti-measles antibody detection examined by enzyme immunoassay (EIA) and plaque reduction neutralization test (PRNT).

The paper discusses the role of anti-measles antibodies for protection and significance for epidemiological studies determination of antibodies by different serological methods. The comparison of anti-measles virus antibodies levels measured by enzyme immunoassay (EIA) and Plaque Reduction Neutralization Test (PRNT) was described. It was found that the 200 mIU/ml of anti-measles activity measured by PRNT (level protection against symp- tomatic disease) is equivalent of 636 mIU/ml measured by EIA (Enzygnost®Anti-Measles Virus/IgG, Simens).

[The prevalence of active infection with viruses from the family Herpesviridae among members of families with children]. / Czestosc wystepowania aktywnych zakazen wirusami z rodziny Herpesviridae wsród czlonków rodzin wychowujacych dzieci.

INTRODUCTION: Cytomegalovirus infection (CMV) is one of the most common viral infections during pregnancy and one of the most common causes of birth defects in newborns. CMV infection occurs mostly through close contact with small children who can secrete the virus in saliva and urine. Children, especially in preschool and early school can also be a source of infection with other herpesviruses. The aim of the study was to determine the prevalence of active infections caused by viruses from the family Herpesviridae (CMV, EBV, VZV) among members of families with children. MATERIAL AND METHODS: The study included 24 families raising children aged from 2 to 18 years. From all members of the families (46 adults and 39 children) saliva samples were collected from which DNA was extracted. The isolated DNA samples were tested for the presence of CMV, EBV, VZV genetic material by nested PCR. In addition, each family carried out a survey. RESULTS AND CONCLUSIONS: The presence of CMV DNA in saliva samples were detected in members of 7 families and the presence of EBV DNA were detected in members of 11 families. Total DNA of CMV was detected in 8/85 samples of saliva (9.41%), of which 1/46 adults (2.17%) and 7/39 children (17.95%) and EBV DNA was detected in 18/85 tested saliva samples (21,18%) - 13/46 samples from adults (28,26%) and 5/39 samples from children (12,82%). VZV DNA was not detected in any of the tested saliva samples. The obtained results indicate that the active, asymptomatic infections with lymphotropic herpesviruses are common and affect more than 10% (CMV) and 20% (EBV) subjects.

Response of viral specific CD4 T cells to in vitro stimulation with vaccine and wild measles virus strains in vaccinated and naturally infected subjects.

With the implementation of the WHO strategic plan for the elimination of measles, the number of measles cases in European Region has decreased. However, outbreaks are still observed. Although most measles cases affect unvaccinated individuals, cases with vaccinated persons are also reported. Furthermore, it was described that a high percentage of young people in Poland exhibit no presence of anti-MeV IgG despite the high level of vaccination covering no less than 97% of the Polish population. Strong evidence exists that immunity to measles is complex and depends on both the humoral and cellular response and although antibodies have been used as correlates of immunity, it is increasingly being considered that antibody-based definitions of vaccine success or failure may be incomplete. Here, we investigated immunity to measles as the reactivity of CD4 T cells to stimulation with vaccine as well as wild strains of measles virus (MeV) isolated in Poland, in young vaccinated persons and subjects infected naturally. Evidence for the presence of MeV-specific memory cells years after infection or vaccination was found, however the cells ofvaccinees and naturally infected subjects reacted differently in contact with wild and vaccine MeV strains. Furthermore, the presence of a significant proportion of non-responder vaccinees was observed. In conclusion, our results may have implications for studies on the monitoring of the complexity of post-vaccine immune response.

[The use of real-time RT-PCR method for the determination of Toll-like genes expression at mRNA level]. / Zastosowanie metody real-time RT-PCR do oznaczania ekspresji genów receptorów Toll-like na poziomie mRNA.

INTRODUCTION: Toll-like receptors (TLRs) are an important component of a innate immune system. Stimulation of TLRs, through action with helper T cells, could change Th1/Th2 balance and thus affect adaptive immune response. The aim of this work was to optimize the stimulation of the peripheral blood mononuclear cells (PBMC) and the validation of real-time RT-PCR method for determination of Toll-like gene expression in these cells. METHODS: PBMCs from healthy donors were stimulated with measles viruses and ligands for TLR2 and TLR4. For examinations the real time RT-PCR (QuantiFast Assay, Qiagen) was used. Fold change of TLRs expression was normalized to GAPDH and estimated by 2(-deltadeltaCt) method. Validation of real-time RT-PCR method was performed for repeatability and efficiency. RESULTS: The level of gene expression varies between individuals and was dose and time of incubation dependent. The efficiency ofreal-time RT-PCR was 90.4% +/- 10.2 for GAPDH, 87.0% +/- 8.2 for TLR2 and 44.5% +/- 9.2 for TLR4. Repeatability, expressed as relative standard deviation (RSD) for Ct values was less than 0.70% for GAPDH, < 3.2% for TLR2 and < 2.84% for TLR4. CONCLUSIONS: Based on obtained results, the optimal conditions for stimulation were: 10 microg/ml/24h for LPS, 1 microg/ml/6h for Pam3CSK4 and 1250 MeV infectious particles/24h.

New endemic foci of tick-borne encephalitis (TBE) identified in districts where testing for TBE was not available before 2009 in Poland.

BACKGROUND: Tick-borne encephalitis (TBE) is found in limited endemic foci in Poland. Lack of diagnosis limits disease detection in non-endemic provinces. METHODS: In 2009, we enhanced TBE surveillance to confirm the location of endemic foci and inform vaccination policy. In 105 hospitals located in 11/16 provinces, we identified suspected TBE cases through admission ICD-10 codes indicating aseptic meningo-encephalitis or from specimens tested for TBE. The National Reference Laboratory confirmed cases at no cost, by testing serum and/or cerebrospinal fluid using ELISA method. We calculated TBE reported rates as the number of confirmed TBE cases per 100,000 inhabitants. Adjusting to neighbouring districts, we classified districts as non-endemic (<0.1 cases per 100,000 inhabitants), low endemic (> = 0.1 to <1), moderately endemic (> = 1 to <5) and highly endemic (> = 5). We compared surveillance data obtained in 2009 with 2004-2008 baseline data. RESULTS: Among 166,099 admissions, we identified 1,585 suspected TBE cases of which 256 were confirmed. Physicians reported more suspected cases among patients <40 years old (12 cases per 1,000 admissions) than among older patients (8 cases per 1,000 admissions). However, patients <40 years of age were confirmed less frequently (16%), than older patients (35%). Physicians reported more suspected cases in districts classed as endemic during 2004-2008 (12 cases per 1,000 admissions, 77% tested for TBE) than in districts classed as non-endemic (7 cases per 1,000 admissions, 59% tested). Of the 38 newly identified endemic districts, 31 were adjacent to 2004-2008 endemic districts and 7 were isolated. CONCLUSIONS: Enhanced surveillance detected 38 new endemic districts to be considered for TBE vaccination. However, lack of consistent testing in districts believed to be TBE-free remained an obstacle for mapping TBE risk. Although the disease affects mostly older adults and the elderly, more attention is given to the diagnosis of TBE in young patients. Solutions need to be identified to sustain sensitive, acceptable and affordable TBE surveillance in all districts of Poland. Also, higher attention should be given to the diagnosis of TBE in the elderly.

The influence of toll-like receptor stimulation on expression of EBV lytic genes.

Epstein-Barr virus (EBV) establishes latency in the resting memory B-cell compartment. It has been recently suggested that maintenance of chronic infection is dependent on periodic reactivation. Although the stimuli for EBV reactivation in vivo during natural infections are largely unknown, there is evidence indicating that heterologous infections could trigger herpesviruses reactivation. The purpose of this work was to identify the influence of Toll-like receptors stimulation on EBV replication in EBV latently infected Burkitt lymphoma cells (P3HR-1, Raji and Namalwa). The cells were stimulated with Pam3CSK4 (synthetic triacylated lipoprotein), PolyI:C (synthetic analog of dsRNA), LPS (lipopolysaccharide from E.coli), measles virus (MeV) and PMA (phorbol myristate acetate). Non-stimulated cells (NS) served as control. EBV expression was investigated at mRNA level for three viral lytic genes: BZLF1 (immediate early, ZEBRA), BALF2 (early, EA) and BcLF1 (late, VCA). Additionally, the effect of stimulation on NF-kBp65 and inflammatory cytokines (IL-lb, IL-6, IL-8, IL-10, IL-12p70, and TNF) was investigated. Stimulation of TLRs led to limited changes in EBV expression manifesting as increase of ZEBRA at mRNA level in cells treated with PolyI:C and Pam3CSK4. Stimulation with PolyI:C, Pam3CSK4 and LPS also lead to considerable increase of NF-kBp65, while increased levels of inflammatory cytokines were observed for IL-8, TNF and IL-6 in cells treated with PMA and MeV. In conclusion, the results of our experiments support the suggestion that TLRs stimulation with microbial ligands influences EBV virus replication.

[Influence of selected preanalytical factors on viral DNA detection by PCR method]. / Wplyw wybranych czynników przedanalitycznych na wyniki oznaczen wirusowego DNA metoda PCR.

INTRODUCTION: Obtaining a reliable laboratory test result depends on many factors, among which preanalytical factors play a significant role. The aim ofthis study was to determine the effect of temperature, storage time of samples and number of freezing and thawing cycles on the results of tests carried out by PCR. METHODS: The study was conducted in a model of cytomegalovirus (DNA) and with four types of clinical material: whole blood, serum, cerebrospinal fluid, urine and archival samples. After contamination with CMV clinical samples were incubated under various conditions for a specified period of time or subjected to cycles of freezing and thawing. The presence of DNA - CMV were determined by nested PCR method. RESULTS: The results revealed that in the case of applied levels of contamination and in model used in the study: 1) CMV DNA in samples of clinical material (blood, serum, cerebrospinal fluid, urine) for testing by PCR remains stable for at least 5 days at room temperature or refrigerated and at least 7 days when frozen, 2) Repeated freezing and thawing clinical specimens has no influence on the result of the presence of viral DNA, 3) Isolated viral DNA is stable in the temperature of the freezer and can be subjected to at least 20 freeze-thaw cycles without affecting the PCR results. CONCLUSIONS: Viral DNA in clinical specimens examined in the applied experimental conditions is stable.

Influence of chlorpyrifos on the profile of subpopulations of immunoactive cells and their phagocytic activity in an experimental in vivo model.

Many environmental factors, including pesticides, cause immunological system disorders by inducing changes in humoral and cellular response. They may stimulate or trigger immunological autoaggression, hypersensitivity and allergy, as well as lead to immunosuppression, thus increasing the incidence of infectious diseases and cancers. Such activity is also attributed to organophosphorus compounds used in agriculture as insecticides, and commonly in households as biocides. The aim of the study was to define possible mechanisms of the immunotoxic activity of the chlorpyrifos (an organophosphorus compound) on experimental animals following their exposure to the compound via the oral route. The present study attempts to define the influence of chlorpyrifos on the profile of subpopulations of immunoactive cells: B, T, CD4+, CD8+, and NK, and on their phagocytic activity in an experimental in vivo model. For this purpose, the Wistar rats, were exposed orally to increasing doses of chlorpyrifos: 0.1 LD(50), 0.15 LD(50), 0.2 LD(50), 0.3 LD(50) and 0.4 LD(50) for 28 days. In the study animals, we failed to demonstrate a statistically significant decrease in the phagocytic activity of the granulocyte.

[Presence of IgG class antibodies anti-measles virus in sera of subjects in different age]. / Wystepowanie przeciwcial klasy IgG dla wirusa odry w surowicach os6b w róznym wieku.

INTRODUCTION: The increase of measles incidence in Poland was recently observed. Furthermore, the analysis of routine serological tests performed in the department of virology, NIPH-NIH revealed, that nearly half of young people (20-30 years old) have no antibodies against measles virus. The paper presents results of IgG specific for measles virus prevalence in the sera of vaccinated and unvaccinated subjects, which aimed to make the selection of groups for immunological memory research. METHODS: Total of 100 persons were examined based on results of determination of the presence of IgG anti-MeV: 26 people born before and 74 born after 1972 year. From this group, 55 participants were selected for further study and divided into 3 groups (1) subjects born before 1972, unvaccinated against measles and seropositive as a result of natural infection, (2) subjects born after 1972, vaccinated against measles but seronegative or with traces ofanti-MeV IgG presence, (3) subjects born after 1972 seropositive due to vaccination. Selected persons are subject to further examinations include determination the number of leukocytes and lymphocytes profile. RESULTS: The level of anty-MeV IgG antibodies in subjects after natural infection was significantly higher compared to levels obtained by vaccinations. No significant differences in the immunological parameters which could influence on immune response were observed. CONCLUSIONS: Obtained results lead to search other factors that may affect the weak postvaccinal humoral response.

[Effect of stimulation with the measles virus on expression of early activation markers on CD4+ T lymphocytes]. / Wplyw stymulacji wirusem odry ekspresji wczesnych markerów aktywacji limfocytów T CD4+.

Elimination of measles is one of the priority plans of WHO. The success of this plan depends on the development of long lasting, postvaccinal immune response. The aim of this study was to present the effect of stimulation with different strains of measles virus on the expression of T-helper cell (CD4+ T) early activation markers in people with different history of measles infection and to determine the correlation between the activation and dose of virus used for stimulation. The study was conducted using material derived from two patients: one seropositive due to natural infection and one vaccinated, with traces of anti-MeV IgG antibodies. In the CD4 T helper cells, the expression of CD69 receptor and the ability of the cells to produce INF after stimulation with the vaccine-derived or wild-type strain of measles virus was determined. For antigen-specific stimulation the virus suspension containing about 100 infectious particle, its tenfold and hundredfold dilutions was used. We found that the expression of T-helper cells early activation markers depended on the strain of the measles virus used for the stimulation, type of the immune response (postvaccinal, natural infection), and in the case of CD69 expression also on the dose of the virus used for the stimulation.

Etiology of measles suspect cases reported in 2006-2007 in Poland.

To achieve measles elimination, an efficient surveillance system for rash illnesses is necessary. The aim of the present study was to ascertain which viruses, other than measles, are causing measles-like illnesses (MLIs) in Poland. Serum samples (n=278) collected from MLI cases and submitted to the National Reference Laboratory during 2006-2007 were investigated for anti-measles (MeV), rubella (RUBV), parvovirus B19 (B19V), Epstein-Barr (EBV) and herpesvirus type-6 (HHV-6) IgM presence. Age was strongly associated with MLIs etiology. In the youngest age group, 0-4 years, MeV and HHV-6 infection were prevailing, while in group of 5-9 years--RUBV and B 19V. Measles was confirmed more often in patients with high fever (p < 0.001) and with rash lasting longer than 5 days (p < 0.001). The type of rash was not significantly associated with MeV infection. Our results strongly suggest that according to WHO EURO strategic plan, Poland is close to elimination phase. High number of MLIs were caused by pathogens other than measles. Addition of anti-B 19V IgM testing to routine MLIs screening protocol may improve system performance in the more advanced stages of measles elimination.

Is interleukin-8 an additional to histopathological changes diagnostic marker in HCV-infected patients with cryoglobulinemia?

PURPOSE: The aim of this study was to analyze histopathological changes in the liver and serum inflammatory cytokine level in hepatitis C virus (HCV)-infected patients with and without cryoglobulinemia. METHODS: The study group consisted of 34 patients with chronic hepatitis C, confirmed by serological and virological markers. Ten out of 34 patients had cryoglobulinemia. The control group consisted of 21 healthy persons. Liver biopsy specimens of HCV-infected patients were evaluated by light microscopy using the grade and the stage according to Batts and Ludwig classification. The quantitative measurements of IL-1ß, IL-6, IL-8, IL-10, IL-12p70, and tumor necrosis factor in sera were performed by flow cytometry. RESULTS: The mean age of HCV-infected patients with cryoglobulinemia was higher than age of HCV-infected patients without cryoglobulinemia. Microscopic examination of liver biopsy specimens revealed necroinflammatory activity slightly more prominent in patients with cryoglobulinemia. The most prominent inflammatory changes connected with abundant lymphoid aggregates in most of the examined portal tracts and piecemeal necroses were diagnosed in patients with several extrahepatic manifestations, such as cutaneous manifestations, nephrotic syndrome, polyneuropathy, and arthropathy. Liver fibrosis was similar in patients with and without cryoglobulinemia. CONCLUSIONS: The serum levels of all proinflammatory cytokines, especially IL-8, were significantly higher in the patients with cryoglobulinemia in comparison with the patients without cryoglobulinemia and healthy persons. All microscopic features did not correlate with the level of any investigated proinflammatory cytokines.

[Effect of storage conditions of clinical materials on virological tests results by RT-PCR]. / Wplyw warunków przechowywania materialu klinicznego na wynik wirusologicznych oznaczen metoda RT-PCR.

Obtaining a reliable laboratory test result depends on many factors, among which preanalitical factors play a significant role. The aim of this study was to determine the effect of temperature, storage time of samples and number of freezing and thawing cycles on the results of tests carried out by RT-PCR. The study was conducted in a model of measles virus (RNA). The results revealed that: (1) Samples of clinical material (serum, cerebrospinal fluid, urine) for testing by RT-PCR can be stored for at least 5 days at room temperature or refrigerated and at least 7 days when frozen, (2) Freezing and thawing three times, samples of clinical material does not affect the outcome of the presence of viral RNA, (3) Isolated viral RNA is stable at freezer temperature and can be subjected to at least 20 freeze-thaw cycles without affecting the results.

[Toll-like receptors expression on Burkitt lymphoma cells]. / Ekspresja receptorów Toll-like na komórkach chloniaka Burkitta.

Toll like receptors (TLRs) are an important component of the immune response. They are link between innate and adaptative response. Lymphocytes B express most of the toll-like receptors and they may respond to a broad spectrum of PAMP. Lymphocytes B are one of the major lymphocyte populations in secondary lymphoid tissues, where they represent up to 50% of cells population. These cells are an important element of the defense, largely by using the mechanisms associated with innate response. On the other hand, lymphocytes B are the site of EBV latency, so Burkitt lymphoma cells can may be a convenient model to study the mechanisms associated with EBV infection. The aim of study was to determine the expression of TLRs at the m-RNA level of in Burkitt lymphoma cells treated with ligands for selected TLRs. P3HR, Raji and Namalwa cells were stimulated with Pam3 (10 microg/ml), PolyI:C (25 microg/ml), LPS (10 microg/ml) and measles virus (MeV, moi 0.02). Unstimulated cells and cells treated with PMA (0.5 microg/ml) served as negative and positive controls. After incubation, from stimulated and unstimulated cells mRNA was extracted, RT-PCR reaction was performed and electrophoretic separation was made. The intensity (INT) of bands were determined using the tools for quantitative analysis. In order to analyze the expression of TLR genes, INT values for TLR2, TLR3 and TLR4 in tested cell lines are expressed as %, assuming an average level of GAPDH expression as 100%. The 25% of INT for negative control was accepted as a change in expression level. It was found that the expression of Toll-like receptors in Burkitt lymphoma cells is diverse both in terms of cell type and the type of stimulation.

[Raji, P3HR-1 and Namalwa cells as a model for the study of Epstein-Barr virus (EBV) reactivation]. / Komórki Raji, P3HR-1 i Namalwa jako model badania reaktywacji zakaienia wirusem Epsteina-Barr (EBV).

The aim of the study was to characterize Raji, P3HR-1 and Namalwa cell lines in the aspect of their usefulness for the research on virus Epstein-Barr (EBV) reactivation, with the participation of Toll-like receptors (TLR). During a 12-day experiment, optimal conditions of cultivation (RPMI with 10% FCS at 37 degrees C in 5% CO2) were determined. In these conditions cells showed logarithmic growth. The presence of the DNA EBV was confirmed by the PCR method, showing that 12-day long maintenance of cells does not cause the loss of the virus. The presence of genes encoding TLR2, TLR3 and TLR4 was also confirmed by PCR. The TLRs expression at the mRNA level in cells subjected to 24h stimulation with TLR2, TLR3 and TLR4 agonist (Pam3CSK4, Poly(I:C) and LPS, respectively) was determined by the RT PCR method. The presence ofTLR4 mRNA was confirmed in the case of Namalwa cells stimulated by Pam3CSK and LPS, and P3HR cells stimulated by Pam3CSK4. In the case of Raji cells the expression of none of the receptors was confirmed at the mRNA level in cells with and without stimulation.

[Evaluating of influence of repeated thaw/freeze cycles on IgG and IgM stability]. / Wplyw wielokrotnego rozmraiania próbki na stabilnosc przeciwcial klasy IgG i IgM.

The purpose of this study was evaluating influence of repeated cycles of thawing and freezing serum samples on IgG and IgM stability. Serum positive samples for anti-cytomegalovirus and antimeasles virus IgG and/or IgM were aliquoted. Tubes containing 100 microl aliquot were frozen at -20 degrees C. Samples were repetitively thawed and froze in one to ten cycles. Antibodies presence was examined with commercially available ELISA tests. All samples reminded positive even after ten repeated thaw/freeze cycles.

[Immunity against tick borne encephalitis virus (TBE) in population of forest workers in Bialowieza]. / Odpornosc dla wirusa kleszczowego zapalenia mózgu (kzm) w populacji pracowników lesnych z terenu Bialowiezy.

In Poland, 200 cases of tick borne encephalitis are annually registered. It is about half of all registered cases of viral encephalitis. Immunity acquired after vaccination with TBE inactivated vaccine persists defined time dependent on number of dose of vaccine and individual features of vaccinated person. The aim of this paper was to determine the frequency of IgG antibodies against TBE virus among forestry workers from Bialowieza National Park with regard to information about vaccination against TBE virus. In the group of 59 persons vaccinated against TBE virus, 54 (91.5%) had IgG antibodies against TBE virus. In the group of 32 persons (non-vaccinated or for whom the information about vaccination was not given) 26 (81.3%) were seropositive. Relationships between VE value (determining level of antibodies), age and period passed from the last dose of vaccination were analysed. Taken to account the most disadvantageous circumstances (age = 60, regression intercept minus two standard deviation) antibodies level of VE = 11 (lower limit of positive result) remains for 2,72 years from last dose of vaccine against TBE virus. This result confirm recommendation about necessity to use of complementary dose within 3-5 years, at the same time it should be considered recommendation of necessity ofrevaccination persons 60 years old or above as frequently as every 3 years.