In vitro immune evaluation of adenoviral vector-based platform for infectious diseases

New prophylactic vaccine platforms are imperative to combat respiratory infections. The efficacy of T and B memory cell-mediated protection, generated through the adenoviral vector, was tested to assess the effectiveness of the new adenoviral-based platforms for infectious diseases. A combination of adenovirus AdV1 (adjuvant), armed with costimulatory ligands (ICOSL and CD40L), and rRBD (antigen: recombinant nonglycosylated spike protein rRBD) was used to promote the differentiation of T and B lymphocytes. Adenovirus AdV2 (adjuvant), without ligands, in combination with rRBD, served as a control. In vitro T-cell responses to the AdV1+rRBD combination revealed that CD8+ platform-specific T-cells increased (37.2 ± 0.7% vs. 23.1 ± 2.1%), and T-cells acted against SARS-CoV-2 via CD8+TEMRA (50.0 ± 1.3% vs. 36.0 ± 3.2%). Memory B cells were induced after treatment with either AdV1+rRBD (84.1 ± 0.8% vs. 82.3 ± 0.4%) or rRBD (94.6 ± 0.3% vs. 82.3 ± 0.4%). Class-switching from IgM and IgD to isotype IgG following induction with rRBD+Ab was observed. RNA-seq profiling identified gene expression patterns related to T helper cell differentiation that protect against pathogens. The analysis determined signaling pathways controlling the induction of protective immunity, including the MAPK cascade, adipocytokine, cAMP, TNF, and Toll-like receptor signaling pathway. The AdV1+rRBD formulation induced IL-6, IL-8, and TNF. RNA-seq of the VERO E6 cell line showed differences in the apoptosis gene expression stimulated with the platforms vs. mock. In conclusion, AdV1+rRBD effectively generates T and B memory cell-mediated protection, presenting promising results in producing CD8+ platform-specific T cells and isotype-switched IgG memory B cells. The platform induces protective immunity by controlling the Th1, Th2, and Th17 cell differentiation gene expression patterns. Further studies are required to confirm its effectiveness.

Comparative study between virus neutralisation testing and other serological methods detecting anti-SARS-CoV-2 antibodies in Europe, 2021

One consequence of the ongoing coronavirus disease pandemic was the rapid development of both in-house and commercial serological assays detecting anti-SARS-CoV-2 antibodies, in an effort to reliably detect acute and past SARS-CoV-2 infections. It is crucial to evaluate the quality of these serological tests and consequently the sero-epidemiological studies that are performed with the respective tests. Here, we describe the set-up and results of a comparative study, in which a laboratory contracted by the European Centre for Disease Prevention and Control offered a centralised service to EU/EEA Member and pre-accession Member States to test representative serum specimens with known serological results, with the gold standard technique (virus neutralisation tests) to determine the presence of neutralising antibodies. Laboratories from 12 European countries shared 719 serum specimens with the contractor laboratory. We found that in-house serological tests detecting neutralising antibodies showed the highest percent agreement, both positive and negative, with the virus neutralisation test results. Despite extensive differences in virus neutralisation protocols neutralisation titres showed a strong correlation. From the commercial assays, the best positive percent agreement was found for SARS-CoV-2 IgG (sCOVG) (Siemens - Atellica IM Analyzer). Despite lower positive percent agreement of LIAISON SARS-CoV-2 TrimericS IgG kit (Diasorin Inc.), the obtained results showed relatively good correlation with neutralisation titres. The set-up of this study allowed for high comparability between laboratories and enabled laboratories that do not have the capacity or capability to perform VNTs themselves. Given the variety of in-house protocols detecting SARS-CoV-2 specific neutralising antibodies, including the virus strain, it could be of interest to select reference isolates for SARS-CoV-2 diagnostic to be made available for interested EU Member States and pre-accession countries.

Novel combinatorial therapy of oncolytic adenovirus AdV5/3-D24-ICOSL-CD40L with anti PD-1 exhibits enhanced anti-cancer efficacy through promotion of intratumoral T-cell infiltration and modulation of tumour microenvironment in mesothelioma mouse model

Introduction

Malignant mesothelioma is a rare and aggressive form of cancer. Despite improvements in cancer treatment, there are still no curative treatment modalities for advanced stage of the malignancy. The aim of this study was to evaluate the anti-tumor efficacy of a novel combinatorial therapy combining AdV5/3-D24-ICOSL-CD40L, an oncolytic vector, with an anti-PD-1 monoclonal antibody.

Methods

The efficacy of the vector was confirmed in vitro in three mesothelioma cell lines - H226, Mero-82, and MSTO-211H, and subsequently the antineoplastic properties in combination with anti-PD-1 was evaluated in xenograft H226 mesothelioma BALB/c and humanized NSG mouse models.

Results and discussion

Anticancer efficacy was attributed to reduced tumour volume and increased infiltration of tumour infiltrating lymphocytes, including activated cytotoxic T-cells (GrB+CD8+). Additionally, a correlation between tumour volume and activated CD8+ tumour infiltrating lymphocytes was observed. These findings were confirmed by transcriptomic analysis carried out on resected human tumour tissue, which also revealed upregulation of CD83 and CRTAM, as well as several chemokines (CXCL3, CXCL9, CXCL11) in the tumour microenvironment. Furthermore, according to observations, the combinatorial therapy had the strongest effect on reducing mesothelin and MUC16 levels. Gene set enrichment analysis suggested that the combinatorial therapy induced changes to the expression of genes belonging to the "adaptive immune response" gene ontology category. Combinatorial therapy with oncolytic adenovirus with checkpoint inhibitors may improve anticancer efficacy and survival by targeted cancer cell destruction and triggering of immunogenic cell death. Obtained results support further assessment of the AdV5/3-D24-ICOSL-CD40L in combination with checkpoint inhibitors as a novel therapeutic perspective for mesothelioma treatment.

Estimated Incidence of Symptomatic Lyme Borreliosis Cases in Lublin, Poland in 2021

Lyme borreliosis (LB), the most common tick-borne disease in Europe, is endemic to Poland. Despite public health surveillance with mandatory reporting of LB cases by physicians and laboratories, many symptomatic LB cases are not included in surveillance in Poland. We estimated the extent of the under-ascertainment of symptomatic LB cases via surveillance in the Polish province of Lublin to better understand Poland's LB burden. The number of incident symptomatic LB cases in Lublin in 2010 was estimated from two seroprevalence studies conducted among adults in Lublin, as well as estimates of the proportion of asymptomatic LB cases and the duration of LB antibody persistence. The estimated number of incident symptomatic LB cases was compared to the number of surveillance-reported cases in Lublin to derive an under-ascertainment multiplier. This multiplier was applied to the number of surveillance-reported cases in 2021 to estimate the number and population-based incidence of symptomatic LB cases in Lublin in 2021. We estimate that there are 5.9 symptomatic LB cases for every surveillance-reported LB case in Lublin. Adjusting for under-ascertainment, the estimated number of symptomatic LB cases in Lublin in 2021 was 6204 (population-based incidence: 467.6/100,000). After adjustment for under-ascertainment, the incidence of symptomatic LB in Lublin, Poland, is high.

Tick-borne encephalitis epidemiology and surveillance in Poland, and comparison with selected European countries before and during the COVID-19 pandemic, 2008 to 2020

BackgroundTick-borne encephalitis (TBE) is the most common viral central nervous system (CNS) infection in Poland. Previous research suggests that its incidence was underestimated in the pre-pandemic period. The COVID-19 pandemic caused a considerable burden on surveillance systems, which could further impact reporting.AimWe aimed to assess the completeness of reporting of TBE in the years 2008 to 2020 and explore the potential impact of the COVID-19 pandemic on reporting to the epidemiological surveillance system, compared with hospitalisations for TBEV and other viral neuro-infections.MethodsWe compared the Polish epidemiology of TBE and other viral infections of the CNS from national surveillance reports with data on hospitalisations from 2008 to 2020 and data from selected European countries.ResultsBetween 2008 and 2020, 3,016 TBE cases were reported to surveillance compared with 3,620 hospitalisations. There was an increasing trend in hospitalisations, while surveillance data demonstrated the opposite, with the largest discrepancy observed in the first pandemic year (354 hospitalisations vs 159 cases reported to surveillance). Serological testing for TBE was used more in the known endemic region of north-eastern Poland and less in non-endemic areas. Other European countries reported higher TBE case numbers and an increase during the COVID-19 pandemic, whereas Poland observed an opposite trend.ConclusionThe sensitivity of TBE surveillance in Poland requires improvement. There are considerable regional differences. Regions that test for TBE intensively report most cases. Policymakers should be made aware of the value of quality epidemiological data for planning prophylactic measures in risk areas.

Molecular diagnosis of COVID-19 – present experiences

Severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2), a new highly emerging and pathogenic for human RNA virus, is responsible for the present COVID-19 pandemic. Molecular diagnostic methods, including real-time reverse transcription-PCR (RT-PCR) assay are the recommended methods for the identification and laboratory confirmation of COVID-19 cases. RT-PCR allows for detection the RNA of the virus in clinical specimens from patients suspected of COVID-19 with high specificity and sensitivity. Testing is still crucial for rapid detection of infected persons, implementation of appropriate measures to suppress further virus transmission and mitigate its impact. In response to demand of a molecular diagnostic test for SARS-CoV-2, within a first few months ongoing pandemic many commercial kits has become available on the market. However, these tests have varied in number and type of molecular targets, time of reaction as well as quality. In this study we compared different commercial tests for the detection of SARS-CoV-2 in clinical samples sending to Laboratory of Department of Virology, NIPH-NIH.

The SARS-CoV-2 ORF10 is not essential in vitro or in vivo in humans

SARS-CoV-2 genome annotation revealed the presence of 10 open reading frames (ORFs), of which the last one (ORF10) is positioned downstream of the N gene. It is a hypothetical gene, which was speculated to encode a 38 aa protein. This hypothetical protein does not share sequence similarity with any other known protein and cannot be associated with a function. While the role of this ORF10 was proposed, there is growing evidence showing that the ORF10 is not a coding region. Here, we identified SARS-CoV-2 variants in which the ORF10 gene was prematurely terminated. The disease was not attenuated, and the transmissibility between humans was maintained. Also, in vitro, the strains replicated similarly to the related viruses with the intact ORF10. Altogether, based on clinical observation and laboratory analyses, it appears that the ORF10 protein is not essential in humans. This observation further proves that the ORF10 should not be treated as the protein-coding gene, and the genome annotations should be amended.

Coronaviral genomes code for several proteins, with the large 1a/1ab being expressed directly from genomic (g)RNA. For the expression of other viral proteins, a set of subgenomic mRNAs is produced during replication. It includes mRNAs for structural (S-E-M-N) and accessory proteins. While the function of structural proteins is well described, the function of the latter ones is under debate. Some of them are required for replication, while others are dispensable in vitro but essential in vivo. Initially, 10 open reading frames (ORFs) were annotated in the SARS-CoV-2 genome, amongst which ORF10 is the most peculiar, as it does not share sequence homology with any known protein. Shortly after the genomic sequences became available, speculations on this protein's role in pathogenesis and innate immunity breaching started. Here, we identified two patients infected with SARS-CoV-2 variants with the ORF10 gene prematurely terminated. The disease was not attenuated, and the transmissibility was maintained. The in vitro study showed that the ORF10 is also not essential for replication. Consequently, ORF10 should not be treated as the protein-coding gene, and the genome annotations should be amended.

From Conventional Therapies to Immunotherapy: Melanoma Treatment in Review

Simple Summary

Here, we review the current state of knowledge in the field of cancer immunotherapy, focusing on the scientific rationale for the use of oncolytic viruses, checkpoint inhibitors and their combination to combat melanomas. Attention is also given to the immunological aspects of cancer therapy and the shift from conventional therapy towards immunotherapy. This review brings together information on how immunotherapy can be applied to support other cancer therapies in order to maximize the efficacy of melanoma treatment and improve clinical outcomes.

Abstract

In this review, we discuss the use of oncolytic viruses and checkpoint inhibitors in cancer immunotherapy in melanoma, with a particular focus on combinatory therapies. Oncolytic viruses are promising and novel anti-cancer agents, currently under investigation in many clinical trials both as monotherapy and in combination with other therapeutics. They have shown the ability to exhibit synergistic anticancer activity with checkpoint inhibitors, chemotherapy, radiotherapy. A coupling between oncolytic viruses and checkpoint inhibitors is a well-accepted strategy for future cancer therapies. However, eradicating advanced cancers and tailoring the immune response for complete tumor clearance is an ongoing problem. Despite current advances in cancer research, monotherapy has shown limited efficacy against solid tumors. Therefore, current improvements in virus targeting, genetic modification, enhanced immunogenicity, improved oncolytic properties and combination strategies have a potential to widen the applications of immuno-oncology (IO) in cancer treatment. Here, we summarize the strategy of combinatory therapy with an oncolytic vector to combat melanoma and highlight the need to optimize current practices and improve clinical outcomes.

Problem of rubella in Poland after compensatory outbreak in 2013

The attempt to estimate the real number of rubella cases in the years 2015-2016 in Poland was presented in this paper. The relations between number of reported cases of measles in 2006-2015y., the number of laboratory-confirmed cases of rubella among cases suspected of measles and the proportion of rubella among patients suspected of measles in the last 10 years as well as the results of serological examination in samples from 74 patients suspected of rubella collected in the first half of 2016 year were analysed. The sera from patients suspected of rubella were collected in cooperation with the State Sanitary Inspection. The analysis of data collected during the study-cases of suspected measles (2006-2016) and rubella infections (in 2016y.) indicated high over-registration of rubella in recent years in Poland, which is associated with a very low rate of laboratory confirmed cases.

Selected aspects of filoviruses in the view of Ebola virus disease epidemic

Ebola virus disease (EVD) is a zoonosis of high virulence in humans. Current epidemic in West Africa is the largest EVD epidemic reported so far, exceeding the number of cases notified and geographical regions affected. This article discusses selected aspects of Ebola virus biology and ecology which are of significance for the processes of primary infection in humans and the spread of epidemic in population. A special attention was drawn to the issues essential for the diagnosis of infection and safety of testing.

Patients' age and the dynamics of IgM for L. pneumophila sg1

MATERIAL AND METHODS

The results of IgM L. pneumophila sg1 test in 304 adults and 270 children performed at NIPH-NIH in 2004-2007 were analyzed to determine the effects of patients' age and the interval between collected sera on the results and the interpretation.

RESULTS

Significant difference in the level of IgM, depending on the age of the patients (P0 = 0.0084) was found. Positive results (in total 20.4% of patients) were the most frequently observed in patients aged 19-29 years (42.5%), and the least--in patients 60 y.o. and < 2 y.o. (7%). Average and median levels of IgM in these two groups (+60 y.o. and < 2 y.o.) were similar and significantly different from the results in the other groups. From 44 adults and 33 children > or = 2 sera were collected. There was a significant difference in the interval between collecting the first and second serum sample in adults (mainly 3-5 weeks) and children (mainly 2-4 weeks). Significant increase of IgM levels was observed in children when the interval between 1 and 2 sample didn't exceed 4 weeks, while in adults this change was also observed at > 5 weeks (25% of patients). No significant differences in the analysis of the IgM ratio in children (1.25-14) and adults (1.5-26) was found, but longer persistence of IgM in adults than in children was observed.

CONCLUSIONS

Demonstrated trend of faster decline in the level of IgM among children than in adults indicated that in suspected case of legionellosis in children, the serum sample should be taken up to 4-5 weeks after the onset, and at intervals of 1-2 weeks maximum.

Imported cases of dengue in Poland and their diagnosis

Infections with dengue virus are transmitted by mosquitoes. In tropical areas, it is mainly spread by Aedes aegypti while in countries with lower temperatures by Aedes albopictus. Since 2010, autochthonous cases of dengue are also reported in Europe. There are 4 serotypes of dengue virus (DENV). No correlation between clinical presentation of disease and virus type, however, were determined. Nevertheless, reinfection with different type of DENV may lead to a serious, life-threatening condition. An estimated 100 million persons are infected with dengue virus per year. Of them, approximately a half (mainly children) develop the symptoms of dengue fever (DF), dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS). Fatality is high in case of severe dengue. Dengue is a serious condition provided there is a presence of IgG antibodies directed against antigens of particular DENV serotypes, associated with primary infection caused by different serotype or transferred from infected mother to her child. For adequate dengue laboratory diagnosis, it is required to apply a set of various diagnostic methods. Within the family Flaviviridae, cross-reactivity is reported, which may lead to the occurrence of false-positive results. In Poland, differential diagnosis with different Flavivirus species is of special importance as it is an endemic area for tick-borne encephalitis (TBE). Thus, data regarding history of patient's immunization against TBE or yellow fever should be also taken into consideration as important in interpretation of results of serological examination.

Persistent colonization of 2 hospital water supplies by L. pneumophila strains through 7 years--sequence-based typing and serotyping as useful tools for a complex risk analysis

Contamination with Legionella spp. of hot water system (HWS) in hospitals is a considerable problem and elimination of bacteria poses difficulties. Obligatory control of Legionella spp. in hospital HWS was implemented in Poland in 2008y. After that, Legionella spp. has been isolated repeatedly from HWS of the majority of hospitals. The aim of our study was to confirm the permanent colonization with Legionella spp. of 2 hospital HWSs based on the antigenic (serogroup/subgroups) and genetic properties (SBT, rtxA) of L.pneumophila strains isolated in 2004-2011. The dynamic of L.pneumophila population was also examined due to methods of disinfections applied during 7 years. Totally, 134 environmental samples were collected from two hospitals in 2004-2011 (118 from HWSs). During the study disinfection by chlorine dioxide was implemented in both hospitals, while thermal shock was added in the hospital A. Isolated L.pneumophila were serogrouped (105 strains) using Dresden MAb Panel, genotyped by sequence based typing (53) and by harboring of rtxA gene (58 isolates). Legionella spp. were still presented in both systems after 7 years. Exactly the same strains (ST1, ST87, ST114, ST992) were found in the hospital B. While changes of L.pneumophila population were observed in the hospital A: strains still occurred after 7 years (ST835 Sg6, ST114 Sg6); modified antigenic properties (ST835 - Sg12 vs. Sg6); eliminated or maybe not detected (ST81, ST838, ST959). Moreover, the majority of examined strains ST1 (Sg1, OLDA) harboured rtxA gene (hospital B). Our results and data in the EWGLI SBT base indicated higher risk of Legionella infection in the hospital B than A--because of heavy colonization with L.pneumophila ST1. The risk assessment of Legionella infection based only on technical parameters, extent of colonization/contamination level may be not completed. It should be supplemented with the additional examination: serotyping, genotyping and virulence testing of isolated strains.

RSV respiratory infection in children under 5 y.o.--dynamics of the immune response Th1/Th2 and IgE

INTRODUCTION

The imbalance of Th1/Th2 cytokine concentrations and increased level of IgE might be useful tool for prediction of severity of RSV infection among young children and possibility of sequels. The ratio of cytokines Th1/Th2 varied during the disease. THE AIM of our studies was the assessment of immunological response by dynamics of Th1 and Th2 cytokines and IgE in RSV infections.

MATERIAL AND METHODS

Study was done on sera collected from 36 young children hospitalized because of RSV infection and from 16 children with other respiratory tract infection (HMPV, EV, HPIV1-3). Assaying of the serum levels of cytokine Th1 (IL-2, IFN-g, TNF), Th2 (IL-4, IL-6, IL-10) and concentration of IgE has been done. Paired sera (48 patients) were collected in the interval 4-14 days. Reference group consist of 18 children (< 6 months of life) hospitalised because other than respiratory diseases with negative results for viruses tested by PCR.

RESULTS

Among children with respiratory infection the Th1/Th2 ratio was shifted towards Th2, level of IgE increased in comparison to the reference group. Changes in concentration of IL-6, IFN-g, IL-10 were related to RSV infection, mainly bronchitis and bronchiolitis, while the dynamic of TNF concentration was independent on aetiological agent. It was found that the risk factors (prematurity, artificial nutrition) correlated with RSV bronchitis and the levels of cytokines and IgE. Increased level of IL-6 and IL-10 were shown in prematures, and increased concentration of IgE--among artificial nourished children. The time of serum collection affected the level of cytokines and IgE and the effect was depended on the aetiological agent. In RSV infections was observed significant decrease with time of IL-6, IL-10 and IFN-gamma but not IgE (still significantly higher than in the reference group). While the significant decrease of IgE was determined only in other than RSV infections.

CONCLUSIONS

Determined level of cytokines and IgE varied depending on the time of serum collection. Observed dynamics in paired sera and IgE might have prognostic value in disease and sequels of RSV infections. Prevention RSV infection in premature infants should be done in any possible way. Breastfeeding is one of the critical elements of prevention of RSV infection.

Sequence-based typing of Legionella pneumophila strains isolated from hospital water distribution systems as a complementary element of risk assessment of legionellosis in Poland

Many factors affect the risk of Legionella infection, such as the design, construction and maintenance of water distribution systems, the presence of individuals who may be exposed and their vulnerability to infection, and the degree of water system colonization and properties of Legionella strains. For epidemiological investigations, two properties of the Legionella strains are usually determined: serotyping and genotyping (sequence-based typing, SBT). In Poland, data regarding legionellosis are fragmentary, despite the fact that this has been a notifiable disease since 2002. The number of reported cases is very low; moreover, the main method of diagnosis is serological examination (delayed diagnosis and cheaper methods), and only single cases of LD were confirmed by culture of bacteria. Therefore, after 10 years of mandatory reporting of the Legionella spp. infection in Poland, the real epidemiological situation is still unknown; however, risk assessment should be carried out, especially in hospitals. In the presented study, comparison of the sequence types of 111 isolated L. pneumophila strains (from hospital water systems) with those present in the EWGLI SBT data was undertaken for complex risk analysis as a complementary element. In total, strains of L. pneumophila belonging to 12 out of 19 STs determined in the presented study were previously reported to the EWGLI SBT database (ST1, ST42, ST59, ST81, ST87, ST114, ST152, ST191, ST371, ST421, ST461, ST520). Among these strains, only 7 STs were previously reported in the amount of ≥10 (mainly ST1, ST42, ST81). Analysis of EWGLI data were carried out and, proportionally, the highest percentage of hospital-acquired strains (clinical and environmental) was found for ST 81, ST421 and ST152, but the largest number was for ST1. Based on the EWGLI data and the presented results, it was found that persistent colonization of HWS of 3 hospitals by strains belonging to ST42, ST1, ST87 indicated an increased risk of legionellosis, especially ST42.

Sequence based typing and pre-absorption test in retrospective analysis of a pseudo-outbreak of Legionella infections differentiates true cases of legionellosis

The aim of this study was elimination of false positive results obtained by the Chlamylege kit. Two serological kits (IgM ELISA L. pneumophila sgs1-7; ImmuView(TM) L. pneumophila sg1/sg3) and pre-absorption tests (with L. pneumophila sg1 and sg3 reference strains antigens) were used. 153 sera (79 patients) were examined. The high correlations were found between the results by both tests. Positive results by ELISA (sgs1-7) were found in 19/79 patients; by ImmuView(TM) (sg1+sg3) in 16/63. In 8 patients, the dynamics of the IgM in pairs of sera was high (ratio ≥2). In 5/8 of those patients seroconversion was determined. Selected pre-absorbed sera (15 pairs) were tested simultaneously by the same tests. In 8/15 pairs of sera, the reduction of IgM levels in pre-absorbed sera was higher than 10. The reduction of IgM differed in sg1 and sg3 tests. The probability of infections due to L. pneumophila sg3 (7 patients) and L. pneumophila sg1 (5 patients) was based on the results of pre-absorption tests. The correlation between ELISA and ImmuView(TM) tests of pre-absorbed sera was statistically significant (Po=0.0389). Moreover, genotyping of L. pneumophila (SBT) directly in the sera of selected 15 patients (high IgM reduction) was carried out. Completed 7 alleles profile (ST36) was determined in one patient. However, a second patient had the same profile of 5 alleles, and similar reactions in pre-absorption tests. At least 4 sources of infections were suggested on the base of genotyping and pre-absorption results.

CONCLUSIONS

Positive results obtained by molecular techniques (eg.PCR) in the diagnosis of Legionella infections should be supplemented by other tests for confirmation of legionellosis. The sequence based typing carried out directly in clinical specimens seems to be a promising method.

Infections caused by RSV among children and adults during two epidemic seasons

Respiratory Syncytial Virus (RSV) is one of the most common causes of lower respiratory tract infections in young children, immunocompromised patients (children and adults), patients with chronic respiratory diseases and elderly people. Reinfections occur throughout the life, but the severity of disease decreased with subsequent infection. The aim of this study was to analyze the frequency of RSV infections in two selected subpopulations: young children (below 5 y.) and adults with chronic respiratory diseases (25-87 y.). Nasopharyngeal swabs (334) collected from October 2008 to March 2010 were examined. The presence of RSV genome was determined by RT-PCR and the presence of RSV antigen by quick immunochromatographic test. Positive results of RT-PCR were found in 45.2% of all swabs: 48.6% samples in 2008; 41.5% in 2009; 50.8% in 2010. The highest frequency of RSV-positive samples was in fall-winter months, but differences in RSV epidemic seasons were found. In the first season (2008-2009) an increased number of RSV infections was observed from November 2008, but in the second season--from January 2010. Generally, the frequency of RSV-positive RT-PCR among children was 53%, among adults 25%. The highest difference was observed in the first three-month period of 2010. RT-PCR positive samples were found in 68.5% of children and 5.9% of adults. However, the RSV antigen was found in 44.4% of samples collected from adults in this period. Our results indicate that the contribution of RSV infections during epidemic season of respiratory tract infections in Poland was really high among children and adults.

Evaluation of the frequency of Pneumocystis jirovecii occurrence in a group of children hospitalized for acute respiratory infections

Primary infection with Pneumocystis jirovecii in small children may cause inflammation of the respiratory tract which requires hospitalization. Lack of characteristic clinical symptoms makes it impossible to recognize P. jirovecii infections without performing laboratory analyses. Nasopharyngeal swabs from 70 children with respiratory tract infections were screened for fragments of the P. jirovecii genome. Pneumocystis DNA was found in swabs taken from two (2.9%) of the tested children: a newborn who was infected in the hospital and a six month old baby admitted to hospital two days after pneumonia was diagnosed. The obtained results confirm that primary P. jirovecii infections may occur in the form of acute respiratory tract inflammations suggesting a viral infection. In differential diagnosis of Pneumocystis infections in children molecular methods are useful as their high sensitivity makes it possible to analyze samples obtained in a non-invasive way.

Detection of hMPV antigen by EIA in clinical specimens

Human Metapneumovirus (hMPV) is one of the latest discovered viruses. It has been classified to Paramyxoviridae family. It is the second viral etiological agent, after RSV, which causes respiratory tract infections (RTI) in children, especially children below 5 years old. It is estimated that 5-25% of RTI in children is due to hMPV. In adults hMPV reinfections are bounded to upper respiratory tract infections. The aim of the study was to establish usefulness of ELISA test in detecting hMPV antigen and to analyze hMPV infection in connection to clinical diagnosis.

MATERIAL/METHODS

273 nasopharyngeal swabs from children (189 swabs) and adults (84 swabs) with respiratory tract infections collected from 2008 to 2010 were examined. Due to similarity of hMPV and RSV viruses and overlapping of their epidemic season rapid immunochromatographic test for RSV antigen detection was also performed in case of 120 samples, hMPV antigen was detected in 24.5% of all swabs (n = 67): in 0.0% probes in 2008, 29.0% in 2009 and 36.8% in first quarter of 2010. The highest rate ofhMPV infection was detected from summer of 2009 till the end of March 2010 (VIII-IX 2009 - 62.5%, X-XII 2009 - 44.1% and I-III 2010 -36.8%). We analyzed respiratory tract diseases reported in patients with hMPV infection. Infection due to hMPV was found in 26.5% of children and 24.0% of adults with recognized pneumonia, respectively in 28.4 and 17.6% of patients with bronchitis. Bronchiolitis was diagnosed in two children with hMPV. RSV and hMPV coinfections were confirmed in 15 out of 120 examined probes. Cross reaction pattern was excluded thanks to ELISA hMPV antigen test which was performed with suspension of RSV and thanks to statistical analysis. Coinfections were confirmed in 8% of pneumonia, 11% of bronchitis and 24.2% of the rest concomitant diagnoses.

CONCLUSIONS

We found hMPV infection as the significant agent ofpneumonia not only in children but also in adults. ELISA hMPV antigen test can be used in diagnosis of etiological agent of respiratory infections in children and adults and in coinfections as well.

[Demographic characteristics of reported cases of legionellosis in years 2005-2009 in Poland in comparison to EWGLI data]

In Poland, all forms of legionellosis are obligatory reported: Legionella pneumonia and extrapulmonary legionellosis (such as Pontiac fever). Total 210 cases caused by Legionella sp. were reported in years 2003-2010. In our study analysis of age, sex, place of residence of 163 patients with legionellosis reported in 2005-2009 were done. The majority (74.2%) cases were reported in Region Mazowieckie. Age and sex structure of patients in Poland in years 2005-2009 differ from the data of EWGLI. In Poland, legionellosis was much more frequently reported in children - 46.6% of the total reported, than in other countries. It might be a result of collaboration with the paediatricians during research conducted by our team in 2005-2007. Reported cases of legionellosis were also observed in 10 children aged < or = 2 years. Totally, legionellosis was observed more frequently among girls than in boys (M: F = 1:1,71), and in males (M: F = 1,64:1). It was also found that in smaller towns (< 100 thousand inhabitants) legionellosis was much more frequently diagnosed in girls (Po = 0.0152, 71.1% of ill children) and men (65.8% of adults). In larger cities (> 100 thousand.) differences in incidence between girls and boys and men and women were lower. To sum up: the number of reported cases of legionellosis depends largely on the availability of laboratory tests and the knowledge of physicians. Extension of diagnostic testing in the direction of Legionnaires' disease patients belonging to other than the high risk group increased number of detected cases, including those not so severe.

[Legionnaires' disease--risk factors and symptoms]

The analysis of published data concerning demographic and medical risk factors and clinical manifestation and outcome observed in Legionella pneumonia were presented in this study. The aim of this study was to discuss the problem of high diversity of symptoms of legionnaires' disease as well as risk factors frequency presented in patients with legionellosis. The different risk factors and clinical picture of Legionella pneumonia were presented, depending on kind of infection (sporadic/epidemic), populations and place of infection (travel-associated, nosocomial, community-acquired). The high percentage of patients with legionellosis and with digestive symptoms (15-70%) was pointed. The presence of digestive symptoms like: diarrhea, vomiting, nausea might cause problem in diagnosis because of suggestion of another etiological agent. Moreover, the hypothesis of M.Sabria et al. regarding the correlation between the exposure and kind and clinical manifestation of Legionella pneumonia was discussed.

[Legionellosis in Poland in 2007]

In 2007 the 28 cases oflegionellosis were reported in Poland, the incidence rate was 0.073/100,000, while 86 cases (incidence rate 0.23/100,000) in 2006. The decrease in number and in incidence rate was due to lower number of examined specimens from patients as the financial support from Polish Committee of Research Activity has expired. All the cases were laboratory diagnosed in National Institute of Hygiene, the only place where laboratory tests are performed. Most of them were diagnosed with serological tests--determination with ELISA test the anti-legionella antibodies in IgM fraction of serum gamma globulins, as the most recent reaction for Legionella infection. Only few cases were diagnosed by detection of legionella antigen in urine. All BAL specimens from several patients were negative when examined with culture method, but some were positive with PCR only. Two outbreaks were registered: one in a family (5 patients, 0 death) and one in hospital (4 patients, 3 death cases). Fifteen cases were connected with travel: 14 foreign travel cases, one in Poland. Since 1987 to 2007 the 17 foreign tourists were registered in EU countries as probably infected in Poland.

[Human metapneumovirus (HMPV) infections in young children]

Human metapneumovirus (hMPV) is a recently discovered respiratory virus. hMPV, the second after respiratory syncytial virus (RSV), is leading cause of upper and lower respiratory tract infections mainly in infants and children. hMPV infections have been reported in many countries in all the world, in patients in every age and gender, but children under 5 years are most likely to be susceptible to infections caused by hMPV. The frequency of hMPV infections require hospitalization in this group is 5-10%. Late winter and early spring is the epidemic peak of hMPV infections in a lot of countries. The similar time of hMPV infections and another respiratory viruses is leading to appear coinfections. Many data reported higher frequency of double coinfections (RSV and hMPV), even 60-70%. This coinfections are responsible for 10-fold increase risk of admission children to a pediatric intensive care unit for mechanical ventilation. INF, AdV, PIV, EV are the other viruses cause coinfections with hMPV. The main laboratory method to diagnose hMPV infections is detect viral RNA and viral antigen in the sample.

[Legionellosis in Poland in 2006]

In 2006 the 89 cases and in 2005 the 21 cases of legionellosis were reported in Poland, the incidence rate was respectively 0.23 and 0.055/100 000. Legionellosis is a notified disease in Poland since 2002, but laboratory diagnostic methods were introduced even earlier, in 1997. The increasing trend in incidence rate was due to an active cooperation with some hospital staff and financial support from Polish Committee of Research Activity. The first time nosocomial Legionella infections were observed in Poland. The outbreak occurred among patients of ophthalmic ward. Five cases with pneumonia were examined by laboratory methods: for two the diagnose was confirmed, for two were presumptive, for one was not confirmed. Three persons died (two with diagnose presumptive, one with confirmed). Every registered case was laboratory examined in National Institute of Hygiene, the only place where laboratory tests were performed. Most of the cases were diagnosed with serological tests--determination with ELISA test the anti-legionella antibodies in IgM fraction as the most recent answer for Legionella infection, few by detection of legionella antigen in urine. All BAL specimens from several patients were negative when examined with culture method, but some were positive with PCR only. Since 1987 to 2006 the 17 foreign tourists were registered in EU countries as probably infected in Poland. Epidemiological investigation with the examination of water system for Legionella sp., cleaning and disinfection (if needed) was done in suspected hotels.

[Respiratory syncytial virus: as an etiological agent of respiratory tract infection in children and adults]

Respiratory Syncytial Virus is the most important cause of respiratory tract infection in infants, young children and immunocompromised adults. RSV disease spectrum includes a wide array of respiratory symptoms, from rhinitis and otits media to pneumonia and bronchiolitis. Studies have implicated severe RSV infection early in life as a risk factor for subsequent development of reactive airway disease. RSV-infected patients indicated increased levels of Th2 cytokines and IgE in the patients sera, suggesting that an allergy-like condition may develop during infection. However, the mechanism by which RSV contributes to asthma is complex and remains largely unknown. Despite its importance as a pathogen, there is no licensed vaccine against RSV. Lack of effective immunoprofilaxis as well as high risk of development of serious sequels make the diagnostics indispensable in controlling spread of the virus.

[Microbiological evaluation of risk of legionellosis and practical methods applied for elimination of Legionella pneumophila from hospital water systems]

Microbiological evaluation of risk of legionellosis was based on the results of water samples collected from hospital water systems examinations. The percentage of positive water samples, number of detected Legionella spp. cfu/100ml, determined serogroup and subgroup of isolated strains as well as genetic virulence markers (rtxA, mompS) were analyzed by multivariable regression tests. The ability to adhere to cells A549 and proliferate in THP-1 cells were also examined. Strong correlation was found between the detected number of Legionella spp. cells (cfu/100ml) and percentage of positive samples, presence of gene depending ability bacteria to move, adhere to A549 cells and presence of mompS gene for special protein building capsule. From other side, correlation between identified cases or infections due to L. pneumophila and presence of gene: rtxA, mompS, and epitop MAb3/l was determined. In conclusion it was indicated that evaluation of risk of legionellosis should be based on ability the legionellae strains to prolify, and grow in water systems and also on virulence properties of isolated strains, especially those producing RTX toxin, flagella and presenting virulence epitop MAb3/l. Two examples of practical application methods for reduction of risk of nosocomial infection were described also. It was shown that cooperation of engineers and microbiologist is essential for effective elimination of Legionella from water systems and reduction of the risk of Legionella infection in hospital.

[Outbreak of hospital acquired Legionnaires' disease in patients of ophthalmic ward. Nosocomial Legionella infections for the first time observed in Poland]

The aim of the paper is to describe the criteria used for identification of first and so far the only one outbreak of hospital bacterial infections due to L. pneumophila. The infected persons were patients hospitalized at ophthalmic ward for more than 10 days. Four patients were found ill among 27 hospitalized (15%) at ophthalmic ward and 3 of them died (75%) in spite treatment in intensive care unit. The source of infection was found in the hospital hot water system. It was shown that L. pneumophila sg 1 and sg 2-14 were settled in the tanks and pipelines of hot water installations. The high number of L. pneumophila sg I and sg 2-14 colony forming units (> 10 000 cfu /100 ml) were found in the water specimens taken from the hospital water system, showing the high risk of Legionella infection for patients. Cleaning and disinfection of hot water system was repeated three times using composition every time modified as stronger mechanical, thermal and chemical methods. Complete elimination of Legionella from hot water system was achieved after cutting off deadlegs of water and replacement of both old hot water reservoirs with new ones. Collected experience served for preparation of guidelines for control and prevention of Legionella infections in hospital buildings, published on National Institute of Hygiene web site A month later Polish Ministry of Health published the Directives concerning the quality of drinking water to which the control of Legionella infection has been included.

[Legionellosis in Poland in 2005]

Legionellosis is a notified disease in Poland since 2001, but laboratory diagnostic methods were introduced even earlier, in 1997. In 2005 the 21 cases of legionellosis were reported in Poland, the incidence rate was 0.055 /100,000. The increasing trend in incidence rate was due to an active cooperation with some hospital staff and financial support from Polish Committee of Research Activity. All cases were laboratory diagnosed in National Institute of Hygiene, the only place where laboratory tests are performed. Most of the cases were diagnosed with serological tests -determination with ELISA test the anti-legionella antibodies in IgM fraction as the most recent reaction for Legionella infection, few by detection of legionella antigen in urine. All BAL specimens from several patients were negative when examined with culture method, but some were positive with PCR only. Since 1987 to 2005 the 15 foreign tourists were registered in EU countries as probably infected in Poland. Epidemiological investigation with the examination of water system for Legionella sp., cleaning and disinfection (if needed) was done in suspected hotels.

Two unrelated cases of septicaemia due to Vibrio cholerae non-O1, non-O139 in Poland, July and August 2006

Two cases of septicaemia caused by Vibrio cholerae non-O1, non-O139 were reported in different regions of Poland during one

[Characteristics of bacteria isolated from body surface of German cockroaches caught in hospitals]

The objective of the study was to identify bacterial flora from external parts of German cockroaches caught in hospitals. The susceptibility of the bacteria to the most important groups of antimicrobial agents was also examined. 80 strains of bacteria were isolated, among them 34 strains of Gram-positive cocci and 31 strains of Gram-negative rods. One of isolated strains of Citrobacter freundii and two strains of Serratia liquefaciens showed ESBL mechanism of resistance and extended level of AmpC--type beta-lactamases. Two Staphylococcus strains (S. epidermidis and S. equorum) were resistant to erythromycin and clindamycin (MLSB mechanism of resistance). Such strains, resistant to antibiotics and chemiotherapeutics may be reservoirs of resistance genes which can be transmitted into other bacteria. Presence of such pathogens on the body surface of German cockroaches, very mobile insects, might create conditions for easy dissemination of them in hospital environment.

[Legionellosis in Poland in 2001-2002 and epidemiological situation in Europe]

Legionnaires' disease is an infectious disease under the internationally approved surveillance agreed by members of European Working Group on Legionella Infections EWGLI. Data over 12,000 cases of legionnaires' disease from 28 countries are included in European data set for years 1993-2000. The overall incidence rate for Europe in 2000 was evaluated as 5,4 cases per million population. The cases was registered as community-acquired, nosocomial or travel often foreign travel associated. Most 2,799 (70.7%) of the cases in 1999-2001 were confirmed by detection of Legionella antigens in urine of patients or by serological findings 205 (18.1%); in them seroconversion was found in 9.5% and high titer in single serum specimen in 8.6% of cases. Culture proven were only 109 (9.6%) cases, and 1.6% of cases by other methods, PCR included. In Poland in 1997 the laboratory examination of samples for diagnosis of Legionella infections started in National Institute of Hygiene. In 2001-2002 the 290 samples were examined. Five cases were laboratory confirmed, but the results of 16 specimen examined was only presumptive positive and for 8 samples equivocal. In comparison with other european countries the number of examined samples is still much to small to find legionnaires' disease cases. The minimum 220 cases by year may be expected in Poland. To find such number the examination of antigenuria should be performed in patients with pneumonia hospitalised in intensive care units because of acute respiratory insufficiency.

[Out-of-laboratory control screening of growth mediums used by sanitary service laboratories for isolation of pathogenic enteric bacteria from fecal specimens]

The aim of the study was to test the selective-differential plating mediums used for isolation of Salmonella and Shigella for routine stool specimens examination for epidemiological and sanitary purpose. Three plates of any such medium used in the laboratories in 37 Sanitary Service Stations in Poland were obtained. The specimens of Mac Conkey Lactose Bile Salt Agar and SS Agar were obtained from all laboratories, Hektoen Enteric medium from 8 and EosinMethylene Blue Agar from only one laboratory. The desiccated substrates of these mediums originated from 11 manufactures. The mediums were inoculated by "drops" method. The five control strains of selected taxons were chosen from National Institute of Hygiene strains collection. The quality of growth was evaluated by comparison with the growth on two control mediums: the general outlook of bacterial colonies, size and number of cfu/ml was taken under consideration. It was found that the results were satisfying for Hektoen medium, Levine and all but two Mac Conkey's medium specimens. The results of growth on SS medium were much worse: only on 10 specimens out of 39 checked supported properly the growth of all the five control strains. On 18 specimens the growth appeared after 48 hours of incubation and the size of colonies was too small to be isolated. On 11 there was no growth on 1, 2 or 3 control strains. The need of systematic extra-laboratory control of plating mediums used for examination stool specimen was shown.

[Pontiac fever--non-pneumonic legionellosis]

Pontiac fever is a non-pneumonic, epidemic form of legionellosis. The symptoms are similar to flu: fever, tiredness, myalgia, arthralgia, headache, cough, sore throat and nausea. The incubation period is from 30 to 90 hours, approx. 36 h., the attack rate is high: 70-90%. There are no differences in sex and age of ill people, the same number of women and men or children were affected. Unfortunately, ill children symptoms might be differ: higher fever (40 C), lack of leukocytosis with left shift, shorten incubation period. The etiological agents are usually bacteria: Legionella pneumophila sg 1, sg 6 and Legionella micdadei. Diagnosis of Pontiac fever is after finding seroconversion or high titre of antibody to Legionella in serum samples or L. pneumophila antigen in urine sample. Pontiac fever cases are frequently found during epidemiological investigation of legionnaires' disease case. Detection of Pontiae fever might be a marker of contaminated with Legionella environment and a risk of live-threatened pneumonia.

[Legionellosis--a new infection in Poland]

Legionellosis became a notifiable disease in Poland in January 1st 2002; however, research on Legionella infection started earlier. Our study of laboratory methods for investigation Legionella infecting humans and waters brought some knowledge on Legionella infections in Poland. The aim of the publication is to present up-to-date findings concerning epidemiology and laboratory methods for surveillance of Legionella infections in European countries and of our own laboratory experience on surveillance of Legionella infections in Poland as well as some retrospective data on the research on Legionella. For the first time Legionella was described in Poland as amoebic pathogen in 1954. In the present investigation the level of water contamination by Legionella in buildings of different institutions was examined. The strains of Legionella pneumophila sg 2-14 were found in 30-100% of water samples collected from hotels, banks, factories and inhabited houses. The level of antibodies to antigens of L. pneumophila sg 1 measured in over 500 serum samples of healthy persons by microagglutination test indicated that titre 256 found in the serum of patient confirm legionellosis. The serological tests were also used for epidemiological studies in an outbreak of legionellosis in Poland. Altogether 403 specimens from hospitalised patients send by hospitals all over the country were diagnosed and 19 were found positive for Legionella infection. The further research on legionellosis is needed.

[Legionella sp.--laboratory diagnosis of infections in humans and detection in environmental water]

Legionella sp. is the etiological agent of Legionnaires Disease and the Pontiac Fever, one of the new emerging diseases. Legionella are common in natural environment but in low number of bacteria cells, especially in comparison to other bacterial flora. Because of special nutritious requirement and long time of Legionella generation, the isolation of bacteria and the diagnosis of legionellosis cause many problems. In this publication some methods for detection of Legionella sp. in environmental water and clinical samples are presented and evaluated.

[Evaluation of cytotoxic activity of Vibrio cholerae non-01 culture filtrate on established cell lines and human diploid cells]

The cell-destroying effect of cell free filtrates of 90 V. cholerae non-01 cultures was measured by titration method in 3 established cell lines: CHO, HeLa and Vero and in 3 human diploid cells cultures: MRC-5, WI-38 and PZ. The vibrio strains differed in the titre of toxic effect. Most sensitive was CHO cell line, least sensitive were human diploid cell cultures. It was found that bacterial strains produced different substances toxic for various cell lines. Among them NAG-ST toxin produced by 41% of examined strains was identified and hemolysins/cytolysins activity was evaluated. Both may play a role in the pathogenicity of those strains for humans.

Structure of cell envelope components of the primary and secondary forms of Xenorhabdus luminescens

Muropeptide analysis of muramidase-digested murein (peptidoglycan) did not reveal any differences between the primary and secondary forms of Xenorhabdus luminescens. Similarly, no significant differences were found in the overall protein composition of the cytoplasmic and outer membranes of both forms.