POS1318 A NATIONWIDE COHORT STUDY ON CLINICAL AND LABORATORY MANIFESTATIONS IN CHILDREN WITH MULTISYSTEM INFLAMMATORY SYNDROME (MIS-C)

Background:

Multisystem inflammatory syndrome in children (MIS-C) was recognized during the 2020 pandemic of SARS-CoV-2. Because of the relative rarity current knowledge is limited, especially in the European Caucasian population.

Objectives:

To report the epidemiology, clinical and laboratory characteristics of patients with MIS-C in a nationwide cohort study in Slovenia.

Methods:

This is a nationwide prospective cohort study of all consecutive patients with MIS-C, admitted from the beginning of epidemics to 31st December 2020 to University Medical Centre Ljubljana, Slovenia, the only tertiary care pediatric rheumatology center in the country. The inclusion criteria were meeting the CDC criteria for MIS-C. Infection with SARS-CoV-2 was confirmed in all patients by positive antibodies for SARS-CoV-2. Data were collected from the patients’ medical records. Data on the COVID-19 epidemics in Slovenia were collected from National Institute of Public Health. Population data were provided by the Statistical Office of the Republic of Slovenia.

Results:

Twenty-three patients with MIS-C were diagnosed nationwide in Slovenia, all of them in the second wave of epidemics from 14th September to 31st December 2020. All patients were Caucasian and the estimated prevalence of MIS-C was 5.8/100 000 persons younger than 19 years of age. Detailed analyses were available in 20 patients of which 14 were boys (70 %), median age was 12.4 years (4 months to 17.7 years). Two patients (10 %) were treated in the intensive care unit and none of the patients died. Troponin was elevated in 15/20 (75 %) patients during the disease course, and 7/15 (47 %) of these had normal troponin level at admission. The serum level of troponin closely followed the serum level of CRP. Six out of 20 (30 %) patients had elevated pancreatic enzymes in the second week of the disease after treatment was already given,and one patient developed asymptomatic acute pancreatitis with serum lipase level reaching the maximum of 25μkat/L. All patients had elevated levels of D-dimer with no signs of thrombosis. Five patients (5/20; 25 %) had pleural effusions and five patients (5/20, 25 %) had ascites. Half of the patients (10/20; 50 %) had hepatosplenomegaly and eight (8/20; 40 %) had mesenterial lymphadenopathy. Three patients (3/20; 15 %) had radiologic signs of cholecystitis. Two patients had thickened lung parenchyma. All patients received IVIG and systemic glucocorticosteroids. Because of resistant or organ threatening disease 4 patients (4/20, 20%) received high dose methylprednisolone pulse therapy. Biologic therapy with anakinra was started in 2 patients. Nineteen patients (19/20, 95%) received acetylsalicylic acid and prophylactic anticoagulation was prescribed in 15/20 (75%) of patients.

The mean follow up was 50 days (14 – 122). At the last follow-up visit all patients had normal laboratory parameters of inflammation, troponin, pro-BNP, d-dimer values and normal heart function.

Table 1.

Clinical characteristics.

n (%)Fever n (%)20 (100)Fever duration (days) [ min; max]5.9 [4; 8]Headache8 (40)Lymphadenopathy15 (75)Chest pain6 (30)Tachycardia16 (80)Gastrointestinal involvement19 (95)•Abdominal pain16 (80)•Vomiting11 (55)•Diarrhoea9 (45)•Loss of apetite18 (90)Cough7 (35)Skin and mucous involvement14 (70)•Rash12 (60)•Palmar/plantar oedema3 (15)•Lip and mouth changes12 (60)•Bilateral conjunctivitis14 (70)Myocarditis19 (95)

Conclusion. A very high incidence of MIS-C, estimated 5.8/100 000 persons under the age of 19 with a predominantly cardiac involvement but very good outcome was noted in European Caucasian population in a nationwide cohort study in Slovenia. Attention to newly described pancreatic involvement should be raised.

Conclusion:

A very high incidence of MIS-C, estimated 5.8/100 000 persons under the age of 19 with a predominantly cardiac involvement but very good outcome was noted in European Caucasian population in a nationwide cohort study in Slovenia. Attention to newly described pancreatic involvement should be raised.

Disclosure of Interests:

None declared

POS0072 COMPREHENSIVE IMMUNE PROFILING OF 20 CHILDREN WITH MULTISYSTEM INFLAMMATORY SYNDROME

Background:

Multisystem inflammatory syndrome in children (MIS-C) is a rare complication of SARS-CoV-2 infection in the pediatric population, caused by extensive activation of immune system. The understanding of the distorted immune response is still in the early stages.

Objectives:

To analyze comprehensively immune profile in MIS-C patients including detailed serologic response to SARS-CoV-2 in comparison with control groups.

Methods:

Blood samples of consecutive MIS-C patients were collected at admission. Flow cytometric analysis of all lymphocyte populations including T and B cell differentiation was performed. Immunophenotyping was performed by six-color panels for the detection of lymphocyte subpopulations. Anti-SARS-CoV-2 specific antibodies were measured in the patients serum. The IgA and IgG antibodies against S protein, the IgG S1 and S2 specific antibodies, antibodies against nucleoprotein and neutralising antibodies were measured. Patients were assessed for a wide range of auto-antibodies, namely ANA, anti-ENA (Jo-1, PL-7, PL-12, SRP, Mi-2, Ku, Pm/Scl 100, Scl-70), myositis specific antibodies (EJ, MDA-5, TIH-Y, Ro52, SAE-1, SAE-2, NXP-2), anti-dsDNA, anti-phopholipid antibodies (aCl IgA, IgG, IgM, antiβ2GPI IgG, IgM) and ANCA. Control groups to compare specific antibody response consisted of 14 healthy children and 19 healthy adults, who had SARS-CoV-2 infection in the last 2 months.

Results:

Samples of 20 patients were included (14/20 boys, median age 12.4 years). Patients had higher percentage of double negative T cells and low numbers of of cytokine producing T cells Th1, Th2 and Th17. . Numbers of immune competent and CD21+ transitional B cells were also lowered. All patients had positive antibodies against SARS-CoV-2 including neutralising antibodies. Nine (9/19; 47 %) patients had high titer (≥1:160) of neutralising antibodies. Results were compared with 2 control groups; 14 healthy children (7/14 boys; median age 8 years,) and 19 healthy adults, who all experienced SARS-CoV-2 infection in the last two months. Patients with MIS-C had significantly higher levels of anti-S IgA (p<0.0001), patients with MIS-C and healthy children had significantly higher titers of anti-S1 (p=0.001) and significantly lower titers of anti-S2 (p=0.016) in comparison to adults (Figure 1). No differences were found in the titers of neutralising antibodies and anti-N antibodies. All patients were ANA negative, 19/20 patients were anti-ENA negative, whereas 1 patient had anti-Ro antibodies in low titre. Three patients had aCL IgG in medium titre and 2 patients anti-beta2GPI IgG in low titre. Patients were negative for all other autoantibodies.

Conclusion:

The immune response in MIS-C patients is specific with most prominent differences in elevated percentage of double negative T cells and low numbers of Th1, Th2, Th17 and CD21+ transitional B cells. MIS-C patients have distinct serologic response with high anti-S IgA, high anti-S1 and low anti-S2 titres.

Figure 1.

Antibody titres in patient group and control groups. Mean value with SEM s shown.

Disclosure of Interests:

None declared.

The European Virus Archive goes global: A growing resource for research

The European Virus Archive (EVA) was created in 2008 with funding from the FP7-EU Infrastructure Programme, in response to the need for a coordinated and readily accessible collection of viruses that could be made available to academia, public health organisations and industry. Within three years, it developed from a consortium of nine European laboratories to encompass associated partners in Africa, Russia, China, Turkey, Germany and Italy. In 2014, the H2020 Research and Innovation Framework Programme (INFRAS projects) provided support for the transformation of the EVA from a European to a global organization (EVAg). The EVAg now operates as a non-profit consortium, with 26 partners and 20 associated partners from 21 EU and non-EU countries. In this paper, we outline the structure, management and goals of the EVAg, to bring to the attention of researchers the wealth of products it can provide and to illustrate how end-users can gain access to these resources. Organisations or individuals who would like to be considered as contributors are invited to contact the EVAg coordinator, Jean-Louis Romette, at jean-louis.romette@univmed.fr.

Molecular diagnostic and genetic characterization of highly pathogenic viruses: application during Crimean-Congo haemorrhagic fever virus outbreaks in Eastern Europe and the Middle East

Several haemorrhagic fevers are caused by highly pathogenic viruses that must be handled in Biosafety level 4 (BSL–4) containment. These zoonotic infections have an important impact on public health and the development of a rapid and differential diagnosis in case of outbreak in risk areas represents a critical priority. We have demonstrated the potential of a DNA resequencing microarray (PathogenID v2.0) for this purpose. The microarray was first validated in vitro using supernatants of cells infected with prototype strains from five different families of BSL-4 viruses (e.g. families Arenaviridae, Bunyaviridae, Filoviridae, Flaviviridae and Paramyxoviridae). RNA was amplified based on isothermal amplification by Phi29 polymerase before hybridization. We were able to detect and characterize Nipah virus and Crimean–Congo haemorrhagic fever virus (CCHFV) in the brains of experimentally infected animals. CCHFV was finally used as a paradigm for epidemics because of recent outbreaks in Turkey, Kosovo and Iran. Viral variants present in human sera were characterized by BLASTN analysis. Sensitivity was estimated to be 10⁵–10⁶ PFU/mL of hybridized cDNA. Detection specificity was limited to viral sequences having ∼13–14% of global divergence with the tiled sequence, or stretches of ∼20 identical nucleotides. These results highlight the benefits of using the PathogenID v2.0 resequencing microarray to characterize geographical variants in the follow-up of haemorrhagic fever epidemics; to manage patients and protect communities; and in cases of bioterrorism.

The European Virus Archive: a new resource for virology research

The European Virus Archive (EVA) was conceived as a direct response to the need for a coordinated and readily accessible collection of viruses that could be made available to academia, public health organisations and industry, initially within Europe, but ultimately throughout the world. Although scientists worldwide have accumulated virus collections since the early twentieth century, the quality of the collections and the viruses collected may vary according to the personal interests and agenda of the scientists. Moreover, when laboratories are re-organised or closed, collections are no longer maintained and gradually cease to exist. The tragedy of 9/11 and other disruptive activities have also meant that some previously available biological reagents are no longer openly exchanged between countries. In 2008, funding under the FP7–EU infrastructure programme enabled the initiation of the EVA. Within three years, it has developed from a consortium of nine European laboratories to encompass associated partners in Africa, Russia, China, Turkey, Germany and Italy. There is every reason to believe that EVA will continue to expand and ultimately exist as a globally networked, quality-controlled non-profit archive for the benefit of science. Organizations or individuals who would like to be considered as contributors are invited to contact the EVA coordinator, Jean–Louis Romette, at jean-louis.romette@univmed.fr.

Isolation of DNA from archival Papanicolaou stained cytological smears using a simple salting-out procedure

DNA from archival Papanicolaou stained and unstained cytological smears was successfully isolated using a simple, rapid and inexpensive salting-out procedure. The quality of DNA was controlled by polymerase chain reaction (PCR) amplification of segments of the human beta-globin, human beta-actin and human papillomavirus L1 genes. Only negligible differences in amplification efficiency were observed between DNA isolated from stained and unstained smears. The salting-out procedure is a more rapid method for the isolation of DNA than phenol-chloroform extraction and may be used in instances where fresh or cryopreserved clinical specimens are not available.

Molecular and Serological Evidence for Anaplasma platys and Babesia sp. Infection in a Dog, Imported in Belgium, from Southern Spain

This case report describes a dog suffering from a co-infection with Babesia and Anaplasma parasites. Anaplasma platys was found to be responsible for the anaplasmosis by molecular biology techniques, while microscopical and serological evidence was found for a coexistent babesiosis, although this could not be confirmed by polymerase chain reaction. Moreover, the possible risk of import of exotic pathogens is highlighted.

Evaluation of an indirect fluorescence immunoassay for the detection of serum antibodies against Babesia divergens in humans

Since an indirect fluorescence immunoassay (IFA) for the detection of specific antibodies against Babesia divergens in human sera is not commercially available, an in-house prepared B. divergens IFA for the examination of bovine sera was established for serological studies in humans. To determine whether the described IFA is appropriate for such studies, 2 B. divergens antigens (of human or bovine origin) were tested using serum samples obtained from febrile human patients with a history of 'tick bite'. Sera from other species of animals infected with B. divergens, Babesia EU1, B. microti or B. canis were also included for comparative purposes. All serum samples were also tested using a commercially available IFA for the detection of antibodies against B. microti, and the results compared with those obtained using blood smear and molecular techniques. This study showed that the evaluation and standardization of a B. divergens IFA for testing human sera is critical and that different B. divergens antigens provide different end-point titres of antibodies, leading to false negative or positive results. Serological cross-reactivity between B. divergens and Babesia EU1 needs to be taken into account when interpreting IFA results.

Aetiology and Clinical Presentation of Mild Community-Acquired Bacterial Pneumonia

A prospective study was initiated to analyse the bacterial aetiology and clinical picture of mild community-acquired pneumonia in Slovenia using the previously described Pneumonia Severity Index. Radiographically confirmed cases of pneumonia in patients treated with oral antibiotics in seven study centres were included. An aetiological diagnosis was attempted using culture of blood and sputum, urinary antigen testing for Streptococcus pneumoniae and Legionella pneumophila, and antibody testing for Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila in paired serum samples. One hundred thirteen patients were evaluable for clinical presentation and 109 for aetiological diagnosis. At least one pathogen was detected in 62.4% patients. The most common causative agents were Mycoplasma pneumoniae in 24.8%, Chlamydia pneumoniae in 21.1%, and Streptococcus pneumoniae in 13.8% of patients. Dual infection was detected in 8.3% of patients. Most patients suffered from cough, fatigue, and fever. Patients with atypical aetiology of pneumonia differed from those with typical bacterial pneumonia or pneumonia of unknown aetiology in age, presence of dyspnea, and bronchial breathing on lung auscultation. Patients with pneumococcal, chlamydial, and mycoplasmal infections differed in age, risk class, presence of dyspnea, bronchial breathing, and proteinuria. There was an overlap of other clinical symptoms, underlying conditions, and laboratory and radiographic findings among the groups of patients classified by aetiology. Since patients with mild community-acquired pneumonia exhibit similar clinical characteristics and, moreover, since a substantial proportion of cases are attributable to atypical bacteria, broad-spectrum antibiotic treatment seems to be recommended.

The molecular evidence of Babesia microti infection in small mammals collected in Slovenia

In Europe, the zoonotic cycle of Babesia microti has not been determined so far. Recently, B. microti was detected in Ixodes ricinus ticks in Slovenia by using molecular methods. In order to investigate the mammalian hosts of B. microti in Slovenia we collected 261 small mammals representing 11 species. They were tested for the presence of babesial parasites with a PCR assay based on the nuclear small subunit rRNA gene (nss-rDNA). The bank vole (Clethrionomys glareolus) and yellow-necked mouse (Apodemus flavicollis) were infected with B. microti. The prevalence rate was 15.9% for C. glareolus and 11.8% for A. flavicollis. Nucleotide sequences of amplified portions of B. microti nss-rDNA from C. glareolus and A. flavicollis were indistinguishable from each other and identical with those previously described in I. ricinus ticks collected in Slovenia. The results of this study represent molecular evidence of B. microti in small mammals in Europe.

Characteristics of Puumala and Dobrava infections in Croatia

In this study, two different hantaviruses, Puumala virus (PUUV) and Dobrava virus (DOBV), were demonstrated for the first time to coexist and cause hemorrhagic fever with renal syndrome (HFRS) in Croatia. Phylogenetic analysis showed some differences among the nucleotide sequences of PUUV originating from Dinara mountain, which was more closely related to Austrian PUUV than other Croatian PUUV from Mala Kapela mountain. More consistency was found among the Croatian DOBV. HFRS was verified in 85 of 201 suspected cases recorded in 1995 during the largest HFRS outbreak in Croatia. Most of these cases were soldiers. With the exception of the coastal region and islands, all of Croatia was found to be an area endemic for HFRS. A statistically significantly higher proportion of DOBV-infected patients had acute renal failure, visual disturbance, severe thrombocytopenia, and elevated levels of nonsegmented leukocytes, creatine, and total bilirubin. The prevalence of gastrointestinal and electrocardiography disorders also was greater in DOBV-infected patients. Interestingly, significantly more PUUV-infected patients had elevated systolic blood pressure on admission to the hospital. Further prospective studies are necessary to shed more light on differences in HFRS severity associated with PUU and DOB viruses.

Serologic evidence of ehrlichiosis among humans and wild animals in The Netherlands

The seroprevalence of antibodies directed against granulocytic and monocytic Ehrlichia was determined by use of human granulocytic ehrlichiosis agent and Ehrlichia chaffeensis as surrogate antigens. Seven hundred twenty-one serum samples were collected between 1992 and 1999 from febrile patients with unresolved aetiology (n=108), patients suspected of having Lyme disease (n=174), forestry workers (n=154) and healthy controls (n=54) as well as from wild deer (n=96), hares (n=60), wild boar (n=15) and red foxes (n=60). Reactive antibodies against granulocytic Ehrlichia were detected in 4% of febrile patients with unresolved aetiology and in 4% of patients suspected of having Lyme disease. Among the forestry workers, 1% tested positive for antibodies against granulocytic Ehrlichia, whereas all the healthy controls were negative. Antibody reaction against monocytic Ehrlichia was detected in only 2% of the febrile patients. Granulocytic Ehrlichia and monocytic Ehrlichia-reactive serum antibodies were detected in 22% and 3% of the deer samples, respectively, and in 2% of the hares. In wild boars and in red foxes, only serum antibodies reactive against monocytic Ehrlichia were detected in 13% and 7%, respectively. The demonstration of the presence of both granulocytic and monocytic Ehrlichia-reactive serum antibodies among humans and wild animals in The Netherlands indicates that patients suspected of having Lyme disease and febrile patients with unresolved aetiology should be tested for the presence of granulocytic and monocytic Ehrlichia antibodies or by polymerase chain reaction. Furthermore, granulocytic Ehrlichia are most prevalent in humans and animals in The Netherlands.

Probable atypical cat scratch disease presenting as isolated posterior pancreatic duodenal lymphadenitis and abdominal pain

We report a case involving a 15-year-old girl with atypical, clinically unsuspected cat scratch disease (CSD) presenting as isolated posterior pancreatic duodenal lymphadenitis, fever, and abdominal pain. The serological, abdominal ultrasonographic, and CT findings, as well as clinical and epidemiological data, indicate that B. henselae was likely an etiologic agent of CSD in our patient.

Clinical and serological follow-up of patients with human granulocytic ehrlichiosis in Slovenia

An evaluation of the clinical outcome and the duration of the antibody response of patients with human granulocytic ehrlichiosis (HGE) was undertaken in Slovenia. Adult patients with a febrile illness occurring within 6 weeks of a tick bite were classified as having probable or confirmed HGE based on the outcome of serological or PCR testing. Thirty patients (median age, 44 years) were enrolled, and clinical evaluations and serum collection were undertaken at initial presentation and at 14 days, 6 to 8 weeks, and 3 to 4, 6, 12, 18, and 24 months. An indirect immunofluorescence assay (IFA) was performed, and reciprocal titers of > or =128 were interpreted as positive. Patients presented a median of 4 days after the onset of fever and were febrile for a median of 7.5 days; four (13.3%) received doxycycline. Seroconversion was observed in 3 of 30 (10.0%) patients, and 25 (83.3%) showed >4-fold change in antibody titer. PCR results were positive in 2 of 3 (66.7%) seronegative patients but in none of 27 seropositive patients at the first presentation. IFA antibody titers of > or =128 were found in 14 of 29 (48.3%), 17 of 30 (56.7%), 13 of 30 (43.4%), and 12 of 30 (40.0%) patients 6, 12, 18, and 24 months after presentation, respectively. Patients reporting additional tick bites during the study had significantly higher antibody titers at most time points during follow-up. No long-term clinical consequences were found during follow-up.

Diversity of Babesia Infecting European sheep ticks (Ixodes ricinus)

Questing Ixodes ricinus (Acari: Ixodidae) adult and nymphal ticks collected in various parts of Slovenia were tested for the presence of babesial parasites with a PCR assay based on the nuclear small subunit rRNA gene (nss-ribosomal DNA [rDNA]). Thirteen of 135 ticks were found to contain babesial DNA. Sequence determination and analysis of amplified portions of nss-rDNA revealed their identity with Babesia microti and a high degree of homology with Babesia odocoilei and Babesia divergens. The results of this study represent the first genetic evidence of B. microti and B. divergens-like parasites in I. ricinus ticks in Europe.

Prospective assessment of the etiology of acute febrile illness after a tick bite in Slovenia

A prospective study established the etiology of febrile illnesses in residents of Slovenia that occurred within 6 weeks after a tick bite. A combination of laboratory and clinical criteria identified 64 (49.2%) of 130 patients as having confirmed, probable, or possible cases of tickborne disease during 1995 and 1996. Of the 130 patients, 36 (27.7%) had laboratory evidence of tickborne encephalitis, all of whom had clinically confirmed disease. Evidence of infection with Borrelia burgdorferi sensu lato was identified in 26 patients; 10 (7.7%) had confirmed Lyme borreliosis. Of 22 patients with evidence of Ehrlichia phagocytophila infection, 4 (3.1%) had confirmed ehrlichiosis. Infection by multiple organisms was found in 19 (14.6%) of 130 patients. Patients with meningeal involvement (43 [72.3%] of 59) were more likely to have confirmed tickborne disease than were patients with illness of undefined localization (18 [26.5%] of 68; P<.0001). Tickborne viral and bacterial infections are an important cause of febrile illness in Slovenia.

[Bartonella henselae as the causative agent in cat-scratch disease: case report]

In this article we reported typical clinical, primary skin lesion and regional lymphadenitis, and atypical, protracted fever and algic syndrome, characteristics of cat scratch disease (CSD) in a 21-year-old man (a student) from Zadar, Croatia. Laboratory parameters were in normal range. The histopathologic findings of affected lymph nodes included stellate caseating granulomas. By using IFA method a seroconversion of specific IgG antibodies (neg/1:512) and rise of IgM antibodies (1:160/ > 1:320) to B. henselae were detected in paired sera, and these serologic findings indicate on conclusion that B. henselae is probably etiologic agent of CSD in our patient.

Seroprevalence of ehrlichiosis, Lyme borreliosis and tick-borne encephalitis infections in children and young adults in Slovenia

BACKGROUND

Little is known about the seroprevalence of ehrlichiosis in adults and much less about the same in children.

METHODS

One hundred and forty-three healthy children and young adults (6-24 years of age, male to female ratio, 1:1) were assessed for the presence of antibodies to the agents of human granulocytic ehrlichiosis (HGE), human monocytic ehrlichiosis (HME), Borrelia burgdorferi sensu stricto (BB), and tick-borne encephalitis (TBE) virus in Slovenia, where tick-related infections are endemic. Antibodies to HGE and HME agents were assayed by indirect immunofluorescence, and antibodies to BB and TBE by enzyme-linked immunosorbent assay. A questionnaire about tick exposure was answered by all subjects. In the event of a positive result, a detailed interview was conducted.

RESULTS

Of 143 study subjects, 22 (15.4%) had detectable antibodies to HGE agent, 22 (15.4%) were positive to BB, 18 (12.6%) were positive to TBE virus (12 of these were vaccinated) and 4 (2.8%) were positive to the HME agent. The history of persons seropositive to an HGE agent had been uneventful.

CONCLUSIONS

Our study documents a high seroprevalence of HGE in children and young adults in Slovenia, similar to the seroprevalence of LB and higher than that of TBE and HME. Although the majority of these infections are probably asymptomatic or mild, active surveillance for acute HGE infections in children in areas endemic for tick-related infections is necessary.

Evaluation of two commercially available immunoassays for the detection of hantavirus antibodies in serum samples

BACKGROUND

hantaviruses are members of the family Bunyaviridae and the spectrum of clinical symptoms in humans may vary from sub-clinical to severe haemorrhagic fever with renal syndrome (HFRS) or pulmonary syndrome (HPS). Several serotypes have been described from which at least five are pathogenic to humans. Each serotype has a different animal reservoir and geographical distribution. In the acute phase of the disease the clinical diagnosis may be confirmed by serology or by polymerase-chain reaction (PCR).

OBJECTIVE

to evaluate two commercially available immunoassays using sera from hantavirus suspected and non-hantavirus patients: an enzyme immunoassay (EIA) developed by MRL Diagnostics, for the detection of immunoglobulins M (IgM) and G (IgG) against several hantavirus serotypes and an indirect immunofluorescence assay (IFA) from Progen, based on slides coated with Hantaan virus (HNTV) and Puumala virus (PUUV), infected cells.

STUDY DESIGN

a total of 145 serum samples were used for this study. The serum panel included serum samples from patients suspected of mild (n=91), severe (n=10) HFRS and patients with other viral infections (n=44).

RESULTS

the agreement between the MRL EIA and the Progen IFA for the detection of IgM and IgG serum antibodies ranged from 87 to 91%, respectively. In the non-hantavirus group one out of 44 samples was positive by the Progen HNTV IgM IFA, none in the Progen PUUV IFA and two samples in the MRL IgM EIA, resulting in specificities of 98, 100 and 95%, respectively. The sensitivities and specificities of the MRL EIAs compared to the Progen overall PUUV and HNTV IFAs were 90 and 91% for IgM, respectively, and 96% for IgG in both immunoassays.

CONCLUSIONS

the MRL EIA proved to be relatively sensitive and specific assay for the serological diagnosis of mild and severe HFRS.

Genetic analysis of wild-type Dobrava hantavirus in Slovenia: co-existence of two distinct genetic lineages within the same natural focus

Genetic analysis was performed of wild-type (wt) Dobrava hantavirus (DOB) strains from Slovenia, the country where the virus was first discovered and where it was found to cause haemorrhagic fever with renal syndrome (HFRS), with a fatality rate of 12%. Two hundred and sixty mice of the genus APODEMUS:, trapped in five natural foci of DOB-associated HFRS during 1990-1996, were screened for the presence of anti-hantavirus antibodies and 49 APODEMUS: flavicollis and four APODEMUS: agrarius were found to be positive. RT-PCR was used to recover partial sequences of the wt-DOB medium (M) and small (S) genome segments from nine A. flavicollis and one A. agrarius. Sequence comparison and phylogenetic analysis of the Slovenian wt-DOB strains revealed close relatedness of all A. flavicollis-derived virus sequences (nucleotide diversity up to 6% for the M segment and 5% for the S segment) and the geographical clustering of genetic variants. In contrast, the strain harboured by A. agrarius showed a high level of genetic diversity from other Slovenian DOB strains (14%) and clustered together on phylogenetic trees with other DOB strains harboured by A. agrarius from Russia, Estonia and Slovakia. These findings suggest that the DOB variants carried by the two species of APODEMUS: in Europerepresent two distinct genetic lineages.

Intrathecal synthesis of specific antibodies in patients with invasion of the central nervous system by Mycoplasma pneumoniae

Mycoplasma pneumoniae commonly causes respiratory tract infections in humans, but it may also be associated with central nervous system manifestations. The aim of the present study was to determine whether the cerebrospinal fluid taken from patients with neurologic symptoms due to Mycoplasma pneumoniae infection contains specific antibodies and whether the detection of these antibodies can be used for diagnosis. Mycoplasma pneumoniae was isolated from the cerebrospinal fluid taken from nine patients with central nervous system symptoms on admission to the hospital. In addition, Mycoplasma pneumoniae was detected in cerebrospinal fluid using polymerase chain reaction in four other patients. Antibodies to Mycoplasma pneumoniae were detected using the enzyme immunosorbent assay, indirect immunoperoxidase assay and immunoblotting in cerebrospinal fluid samples from 14 of 19 patients included in the study. The indirect immunoperoxidase assay showed high titers of Mycoplasma pneumoniae immunoglobulin G1 (IgG1) and IgM antibodies in cerebrospinal fluid samples of some patients with meningoencephalitis or meningitis. Titers of specific IgA, IgG2 and IgG3 antibodies were lower, while specific IgG4 was not detectable. Cerebrospinal fluid samples with higher antibody titers also contained IgA, IgG1, IgG2, IgG3 and IgM antibodies that recognized the P1 adhesin (170 kDa protein) of Mycoplasma pneumoniae. A comparison of antibody titers of concomitant serum/cerebrospinal fluid samples to Mycoplasma pneumoniae and those to measles virus by enzyme immunosorbent assay suggested the intrathecal synthesis of IgG and IgM antibodies to Mycoplasma pneumoniae in patients with acute meningoencephalitis. Data from this study clearly reinforce previous findings that Mycoplasma pneumoniae is an etiologic agent of central nervous system infections in humans.

Antigenic properties and diagnostic potential of recombinant dobrava virus nucleocapsid protein

Dobrava hantavirus (DOBV) causes severe hemorrhagic fever with renal syndrome in the Balkan region and has been detected recently also in Russia, Estonia, and Germany. DOBV nucleocapsid protein (N) was produced in insect cells, using the baculovirus expression system (bac-DOBV-N), and in E. coli as a truncated (aa 1-165) glutathione-S transferase fusion protein (DOBV-dN-GST). The antigenic properties of bac-DOBV-N were found identical to native DOBV-N when examined by a panel of hantavirus-specific monoclonal antibodies. Enzyme immunoassays for detection of IgM and IgG antibodies were set up using DOBV recombinant N proteins and compared with those based on recombinant Hantaan and Puumala virus N, using panels of sera collected from DOBV, Hantaan and Puumala virus-infected patients. Full-length N protein (bac-DOBV-N) was found to be a more sensitive antigen than DOBV-dN-GST. The sensitivity values for sera from DOBV-infected patients were 100% for bac-DOBV-N and 86% for DOBV-dN-GST by IgM assays, and 98% for bac-DOBV-N and 88% for DOBV-dN-GST by IgG assays. The specificity values were 100% for bac-DOBV-N and 99% for DOBV-dN-GST by IgM assays, and 100% for both antigens by IgG assays.

Comparison of the epidemiological and clinical features of tick-borne encephalitis in children and adults

The aim of this prospective study was to compare epidemiological data and clinical features in children and adults with tick-borne encephalitis (TBE). Patients with aseptic meningitis diagnosed at the University Medical Centre, Department of Infectious Diseases, Ljubljana, Slovenia, from June to August 1997, in whom the diagnosis of TBE was ascertained by the presence of serum IgM antibodies against TBE virus, who were serologically negative for Borrelia burgdorferi sensu lato and had a negative PCR CSF result on enteroviral infection, were included in the study. Out of 213 patients with aseptic meningitis, 80 (37.56%) fulfilled inclusion criteria. There were 20 children and 60 adults. In both groups males predominated. Virtually all patients had headache and fever, and more than 50% suffered from vomiting. The majority of patients in both groups recalled a tick bite, had a biphasic course of the illness, and was found to have obviously expressed meningeal signs. In both groups the median CSF leukocyte count was somewhat lower than 100 x 10(6)/l with a predominance of lymphocytes. Children were more often given antibiotics during the initial phase of TBE than adults (p = 0.0095). Several other statistically significant distinctions (p < 0.05) were found including the frequency of fatigue, malaise, vertigo, photophobia, myalgias, arthralgias, as well as elevated CSF albumin and protein concentration, elevated albumin quotient and IgG quotient; all these findings were more often present in adults. In addition a longer duration of fever, more frequent need for anti-edematous treatment and longer hospitalization were found in adults. Direct comparison of clinical and epidemiological characteristics of TBE in children and adults revealed differences in several clinical and laboratory features and corroborates the previous conclusion that TBE in childhood is a milder illness than TBE in adults.

Spatial and temporal dynamics of Puumala hantavirus infection in red bank vole (Clethrionomys glareolus) populations in Belgium

Dynamics of hantavirus infection and population densities in rodents were investigated from 1996 to 1999 in southern Belgium. Evidence of Puumala infection was restricted to Clethrionomys glareolus. Although the serotype was not determined, antibodies against hantavirus were also found in eight Apodemus sylvaticus. In fall 1996, the seroprevalence in C. glareolus was high (20.1%, 37 of 184) and the infection was widely distributed in the area studied whereas a focal occurrence of positive rodents and lower seroprevalence rates were recorded in spring 1997 (14.3%, six of 42), fall 1997 (6. 6%, 11 of 166), spring 1998 (6.4%, three of 47) and fall 1998 (6.7%, 11 of 165). A pullulation of rodents was observed in spring 1999 and was associated with a markedly higher seroprevalence in C. glareolus (47.7%, 189 of 396). In all seasons, infection rates in adults were higher than in juveniles and subadults. No significant difference of prevalence was recorded between males and females. In two trapping sites, the temporary disappearance of positive animals after a crash in rodent populations suggests that a threshold in density is necessary for the maintenance of the enzootic cycle.

Clinical distinction between human granulocytic ehrlichiosis and the initial phase of tick-borne encephalitis

OBJECTIVES

The aim of our study was to establish clinical and laboratory differences between patients with acute human granulocytic ehrlichiosis (HGE) and patients with the initial phase of tick-borne encephalitis (TBE).

METHODS

Clinical features and laboratory results of four patients with acute HGE (established by the presence of the specific DNA sequences of the HGE agent in whole blood by polymerase chain reaction and/or by seroconversion to the HGE agent by indirect immunofluorescence assay) and 12 patients with the initial phase of TBE (demonstrated by the presence of serum IgM antibodies to TBE virus) were compared. All these patients were uncovered at the Department of Infectious Diseases, University Medical Centre, Ljubljana, Slovenia, during 1995-1996, in a prospective study on the aetiology of febrile illnesses occurring within 6 weeks after a tick bite.

RESULTS

Findings were similar for the majority of the examined parameters including severity of illness, level and duration of fever, presence of headache, leukopenia, thrombocytopenia, and liver - function test abnormalities. Statistically significant differences were found only for arthralgia (P=0.026) and elevated concentration of C-reactive protein (P=0.003); both variables were found more often in patients with acute HGE.

CONCLUSIONS

In a patient residing in the central part of Slovenia, who reports a tick bite followed by a febrile illness with leukopenia and/or thrombocytopenia, the presence of arthralgias and/or an elevated C-reactive protein value directs toward the diagnosis of acute HGE and against the initial phase of TBE.

Diffuse reversible alopecia in patients with Lyme meningitis and tick-borne encephalitis

Alopecia occurring after febrile bacterial and viral infection is a phenomenon well known since the beginning of the century. To evaluate the occurrence of alopecia in tick transmitted disease, 23 adult patients with Lyme meningitis and 71 patients with tick-borne encephalitis were included in a prospective study and were followed up for one year. Diffuse alopecia occurred within three months after the outbreak of disease in 3 out of 23 (13%) patients with Lyme meningitis and in 40 out of 71 (56.3%) patients with tick-borne encephalitis. The mean duration of alopecia was 2 to 3 months and alopecia was reversible in all patients.

Infection of small mammals with Borrelia burgdorferi sensu lato in Slovenia as determined by polymerase chain reaction (PCR)

Thirty-four small mammals collected in the vicinity of Ljubljana were tested for the presence of Borrelia burgdorferi sensu lato by polymerase chain reaction (PCR) of urinary bladder tissues, using universal flagellin primers and species specific rRNA primers. Seventeen small mammals (50%) were found to be positive, and 7 small mammals were infected with two species of B. burgdorferi sensu lato simultaneously. The most commonly found species was B. afzelii (n = 14), followed by B. burgdorferi sensu stricto (n = 7) and B. garinii (n = 3), as determined by species-specific primers. We conclude that PCR is a rapid and reliable method to detect infection with B. burgdorferi sensu lato in small mammals.

A major outbreak of hantavirus infection in Belgium in 1995 and 1996

Haemorrhagic fever with renal syndrome (HFRS) is a human disease characterized by flu-like symptoms, renal dysfunction, and in severe cases, haemorrhagic manifestations. The causative agents of HFRS are Hantaan (HTN), Seoul (SEO), Puumala (PUU) and Dobrava (DOB) hantaviruses. Hantavirus infections are of increasing importance in Europe. Outbreaks occur in Belgium with a 3- to 4-year interval with an increasing number of cases. We describe the largest outbreak so far in Belgium with 217 serologically and clinically confirmed cases in the period between October 1995 and December 1996. We demonstrated that the use of viral antigen derived from a local PUU-strain was able to detect significantly more sera positive for IgM in an immunofluorescence assay. Furthermore, although in some cases SEO, HTN and DOB antibody-reactivities were detected by ELISA, only PUU infections could be confirmed by neutralization test. The presence of an unknown hantavirus serotype circulating in Belgium should be considered.

Hemorrhagic fever with renal syndrome in the Dolenjska region of Slovenia--a 10-year survey

This report describes the first investigation of clinical findings for a larger series of patients with hemorrhagic fever with renal syndrome (HFRS) who were infected with Dobrava virus. From 1985 to 1995, 38 patients with serologically confirmed HFRS were hospitalized at the regional hospital in Novo mesto in the Dolenjska region of Slovenia. On the basis of results of serological examination, 24 patients had Dobrava virus infection, and 14 patients had Puumala virus infection. Complete clinical data were available for 31 patients. Eleven patients underwent hemodialysis for treatment of acute oliguric or anuric renal failure. Four patients, all infected by Dobrava virus, had signs of shock and severe bleeding. Three severely ill Dobrava virus-infected patients died of hemorrhagic complications. We have demonstrated that Dobrava and Puumala viruses coexist in a single region of endemicity and are capable of causing HFRS with significant differences in severity.

Human ehrlichiosis in central Europe

Ehrlichioses are tick-transmitted diseases associated with illnesses of animals for decades, but recently recognised to be emerging human diseases. In the last ten years increasing number of cases of human infections caused by Ehrlichia chaffeensis and granulo-cytic ehrlichia were described in the United States. Several reports also indicate the presence of infection with the human granulocytic ehrlichiosis (HGE) agent in Europe. The first confirmed acute human disease caused by HGE agent was reported from Slovenia. Until 1997, five patients have been discovered in a prospective study on the etiology of febrile illnesses occurring within six weeks following a tick bite, conducted at the Department of Infectious Diseases, University Medical Centre, Ljubljana, Slovenia. The diagnosis of acute HGE was established by seroconversion to the HGE agent and/or molecular identification of ehrlichial organisms. None of the patients had detectable morulae on blood smear examination. Clinical characteristics and laboratory findings were similar to those reported from the United States, although the disease course was relatively mild in the Slovenian cases. All patients recovered rapidly and without sequelae, although only three patients received antibiotic therapy (of whom only two were treated with doxycycline). Many ehrlichiosis cases could go undetected due to a lack of physician awareness, lack of public knowledge, or limited investigation. HGE should now be also included in the differential diagnosis of febrile illnesses occurring after a tick bite in Europe.

Concomitant infection with tick-borne encephalitis virus and Borrelia burgdorferi sensu lato in patients with acute meningitis or meningoencephalitis

From September 1992 to August 1993, 338 patients over the age of 15 years presented to the Department of Infectious Diseases, University Medical Centre Ljubljana, with acute lymphocytic meningitis. In 89 of these patients (26.3%) serum IgM and IgG antibodies against tick-borne encephalitis (TBE) virus were detected, and in 59 patients (17.5%) a borrelial etiology of disease was demonstrated by one or more of the following presence of intrathecal antibody production, seroconversion to borrelial antigens, presence of erythema migrans, and/or isolation of Borrelia burgdorferi sensu lato from skin or cerebrospinal fluid. Of the 148 patients who fulfilled criteria for TBE or borrelial infection, concomitant infection with TBE virus and B. burgdorferi sensu lato was demonstrated in 12 patients (3.6% of all patients presenting with acute lymphocytic meningitis). In the majority of patients with concomitant infection the clinical features at presentation were characteristic of, or consistent with, TBE. In addition, during follow-up studies, eight of the 12 patients subsequently developed signs and symptoms compatible with minor and/or major manifestations of Lyme borreliosis. Six patients were diagnoses with neuroborreliosis based on signs or symptoms and/or laboratory tests. These findings show that in patients with acute lymphocytic meningitis or meningoencephalitis, originating in TBE and Lyme borreliosis endemic regions, the possibility of concomitant infection should be considered.

[Azithromycin in the prevention of Mediterranean spotted fever]

Antibodies to Rickettsia conorii were detected by the indirect immunofluorescence (IFA) assay in 64 (51.6%) out of 124 examinees living in North Dalmatia (Croatia) who had a history of recent tick bites during 1994 and 1995. Positive titers of IFA antibodies to R. conorii were detected in 12 (31.5%) out of 38 examinees with carried out prophylaxis by azithromycin. The usual clinical signs of Mediterranean spotted fever were registered in 22 (25.6%) and asymptomatic infection in 30 (34.8%) out of 86 examinees without prophylaxis. Clinical signs of the disease were not registered in examinees with prophylaxis.

Serological diagnosis of hantavirus infections by an enzyme-linked immunosorbent assay based on detection of immunoglobulin G and M responses to recombinant nucleocapsid proteins of five viral serotypes

Worldwide, hantaviruses cause more than 100,000 human infections annually. Rapid and accurate methods are important both in monitoring acute infections and for epidemiological studies. We and others have shown that the amino termini of hantavirus nucleocapsid proteins (Ns) are sensitive tools for the detection of specific antibodies in hantavirus disease. Accordingly, we expressed truncated Ns (amino acids 1 to 117) in Escherichia coli from the five hantaviruses known to be pathogenic to man; Hantaan (HTN), Seoul (SEO), Dobrava (DOB), Sin Nombre (SN), and Puumala (PUU) viruses. In order to obtain pure antigens for use in an enzyme-linked immunosorbent assay (ELISA), the recombinant proteins were purified by polyhistidine-metal chelate affinity chromatography. Polyclonal animal antisera and a panel of serum specimens from hantavirus-infected individuals from Scandinavia, Slovenia, Russia, Korea, China, and the United States were used to evaluate the usefulness of the method. With both human and animal sera, it was possible to designate the antibody response into two groups: those with HTN, SEO, and DOB virus reactivity on the one hand and those with SN and PUU virus reactivity on the other. In sera from Scandinavia, European Russia, and the United States, the antibody response was directed mainly to the PUU and SN virus group. The sera from Asia reacted almost exclusively with the HTN, SEO, and DOB types of viruses. This was true for both the immunoglobulin M (IgM) and IgG antibody responses, indicating that this type of discrimination can be done during the acute phase of hantavirus infections. Both the HTN, SEO, and DOB virus and the PUU and SN virus types of antibody response patterns were found in patients from the Balkan region (Solvenia).

Tick-borne encephalitis: possibly a fatal disease in its acute stage. PCR amplification of TBE RNA from postmortem brain tissue

Tick-borne encephalitis has occurred regularly in Europe since it was first diagnosed in 1931 by Schneider. The mortality rate of patients with this disease is 1-2%. Death usually occurs in the acute stage of illness. A case report of a 28-year-old patient from Slovenia, who died shortly after the onset of tick-borne encephalitis, is described. The clinical course of disease, results of serological tests, neuropathological findings and polymerase chain reaction amplification of parts of viral genome from postmortem brain tissues are presented.

The hantaviruses of Europe: from the bedside to the bench

In Europe, hantavirus disease can hardly be called an emerging zoonosis; it is rather a rediscovered disease. Since 1934 an epidemic condition with primarily renal involvement has been described in Sweden. Nowadays, hundreds to thousands of cases per year are registered in Fennoscandia, fluctuating with the numbers of the specific Arvicoline-rodent reservoir, the red bank vole, which carries the main European serotype, Puumala (PUU). In the early 1980s, the rat-transmitted serotype, Seoul (SEO), caused laboratory outbreaks throughout Europe, and recent reports also suggest sporadic, wild rat-spread hantavirus disease. In the Balkans, at least four serotypes are present simultaneously: PUU, SEO, the "Korean" prototype Hantaan (HTN) or HTN-like types, and Dobrava, the latter causing a mortality rate of up to 20%. Moreover, recent genotyping studies have disclosed several PUU-like genotypes spread in Europe and/or Russia by other genera of the Arvicoline-rodent subfamily: Tula, Tobetsu, Khabarovsk, and Topografov. Their importance for human pathogenicity is still unclear, but serologic cross-reactions with PUU antigen might have caused their misdiagnosis as PUU-infections in the past.

Genetic and antigenic properties of Dobrava virus: a unique member of the Hantavirus genus, family Bunyaviridae

We examined the genetic and antigenic properties of Dobrava (DOB) virus, a hantavirus associated with severe haemorrhagic fever with renal syndrome in Europe. Cloning and sequence analyses revealed the DOB M segment to consist of 3644 nucleotides, with a coding capacity of 1134 amino acids in the virus complementary-sense RNA (cRNA). Seven potential asparagine-linked glycosylation sites were identified in the M segment gene product, one in the G2 and six in the G1 coding regions. The S segment is 1667 nucleotides long, and has a single ORF in the cRNA capable of encoding a protein of 428 amino acids. Phylogenetic comparisons of the M and S segments of DOB virus to those of other hantaviruses indicated that DOB virus is similar to, but clearly distinct from Hantaan (HTN) and Seoul (SEO) viruses. Certain G2-specific, but not G1-specific monoclonal antibodies to HTN virus reacted to the same titre with DOB and homologous viral antigen. Plaque-reduction neutralization tests indicated that, of the sera tested, only antisera to SEO virus were able to neutralize DOB virus to a titre greater than 1:10; however, this neutralization titre was eightfold lower than that observed with homologous SEO virus. The data reported here confirm that DOB virus is a unique species in the Hantavirus genus, family Bunyaviridae.

Laboratory acquired tick-borne meningoencephalitis: characterisation of virus strains

BACKGROUND

The handling of tick-borne encephalitis (TBE) virus is potentially hazardous, as indicated by a number of laboratory-acquired infections in the prevaccination era.

OBJECTIVES

(1) To reemphasize the hazard of handling TBE virus without being vaccinated by describing the case of a laboratory-acquired full-blown TBE in a microbiologist who isolated the virus from a blood sample. (2) To molecularly characterize the causative virus strain isolated in Slovenia in comparison with the European prototype strain Neudoerfl.

STUDY DESIGN

The virological diagnosis of the laboratory infection was established by serology and virus isolation. The virus was characterized by restriction fragment analysis of PCR products of amplified genomic sequences and a panel of monoclonal antibodies reacting with the major envelope protein.

RESULTS

The laboratory infection, most probably acquired by aerosol, resulted in a biphasic course of the disease with a severe meningoencephalitis in the second phase. Both by restriction fragment and monoclonal antibody analysis the Slovenian virus strains involved were indistinguishable from the European prototype strain.

CONCLUSIONS

This report confirms the potential hazard of handling TBE virus in the laboratory without being vaccinated. The similarity of the virus isolates from Slovenia with the European prototype strain confirms the previously observed homogeneity of TBE virus strains from different European countries.

Evaluation of two commercial amplification assays for detection of Mycobacterium tuberculosis complex in respiratory specimens

To evaluate the usefulness of two standardized commercially available amplification assays for the detection of Mycobacterium tuberculosis: Amplicor test (Roche) and MTD-Amplified direct test (Gen-Probe) a total of 281 respiratory specimens from 198 patients with symptoms of pulmonary diseases were examined and compared with conventional methods. Fifty-seven specimens were positive and 218 negative by both amplification assays. Three specimens were reactive by Amplicor only, and three by MTD only. In comparison with culture, the sensitivity, specificity, positive predictive value and negative predictive value were 96.0, 94.8, 80.0, and 99.1%, respectively, for the Amplicor test; the corresponding values were 94.0, 94.4, 78.3, and 98.6%, respectively, for the MTD. However, when 28 specimens from 14 patients on antituberculous therapy were excluded the improvement in PPV and specificity of both assays was obtained. In conclusion, both commercially available amplification tests are almost equally sensitive and specific and are suitable for the implementation in daily routine work in the specialized clinical laboratories.

Isolation of a strain of a Hantaan virus from a fatal case of hemorrhagic fever with renal syndrome in Slovenia

Hemorrhagic fever with renal syndrome (HFRS) has been serologically confirmed in Slovenia during the last seven years. There is evidence that three hantaviruses (Hantaan, Puumala, and a newly described form termed Dobrava) circulate simultaneously in this area. Recently, a hantavirus was isolated from the urine and brain tissue of a fatal case of HFRS. Positive immunofluorescent reactions with reference human sera and monoclonal antibodies were first recognized after the second cell culture passage. Extensive cross-reactivity between our isolate and prototype Hantaan virus, strain 76-118, and Hantaan-like isolates from the former Yugoslavia, Fojnica and Plitvice, was revealed by enzyme-linked immunosorbent assay with specific rat antisera. The reaction pattern of the isolate was similar to the prototype Hantaan virus by indirect immunofluorescent assay with a panel of monoclonal antibodies. Furthermore, the specificity of the isolates was confirmed by analysis of polymerase chain reaction products of this virus with five restriction endonucleases. This appears to be the first isolation of a strain of prototype Hantaan virus from a fatal case of HFRS in Europe.

Belgrade virus, a cause of hemorrhagic fever with renal syndrome in the Balkans, is closely related to Dobrava virus of field mice

Belgrade virus is a recently described hantavirus that causes severe hemorrhagic fever with renal syndrome (HFRS) in people living in various parts of the Balkan Peninsula. Nucleotide sequencing of the G2-encoding region in the medium (M) segment of the viral genome, reverse transcribed and amplified by the polymerase chain reaction, revealed the Belgrade virus to be substantially different from Hantaan virus and other major serotypes of hantavirus but identical to Dobrava virus, a virus isolated from a field mouse (Apodemus flavicollis) in Slovenia. Belgrade virus may be an important cause of HFRS in the Balkan Peninsula, extending north toward the Alps. It poses a special danger to humans who have close contact with field rodents.

Dobrava virus as a new Hantavirus: evidenced by comparative sequence analysis

Dobrava virus, recently isolated from a yellow-neck mouse (Apodemus flavicollis), captured in a northern Slovenian village where severe cases of hemorrhagic fever with renal syndrome were recognized, was shown by serology and restriction enzyme digestion of PCR-amplified gene segments to be related to previously recognized hantaviruses. To investigate further the relationship of this new isolate to other hantaviruses, a portion of the medium (M) genome segment of Dobrava virus was amplified by PCR and the nucleotide sequence determined. Comparing the nucleotide sequence with the same gene region of other hantaviruses revealed an overall homology of 41.7%. A phylogenetic tree based on pairwise sequence similarity clearly showed that Dobrava virus is genetically distinct, and probably represents a new virus in the genus Hantavirus of the family Bunyaviridae.