Two-field resolution on-call HLA typing for deceased donors using nanopore sequencing.

The current practice of HLA genotyping in deceased donors poses challenges due to limited resolution within time constraints. Nevertheless, the assessment of compatibility between anti-HLA sensitized recipients and mismatched donors remains a critical medical need, particularly when dealing with allele-specific (second field genotyping level) donor-specific antibodies. In this study, we present a customized protocol based on the NanoTYPE® HLA typing kit, employing the MinION® sequencer, which enables rapid HLA typing of deceased donors within a short timeframe of 3.75 h on average at a three-field resolution with almost no residual ambiguities. Through a prospective real-time analysis of HLA typing in 18 donors, we demonstrated the efficacy and precision of our nanopore-based method in comparison to the conventional approach and without delaying organ allocation. Indeed, this duration was consistent with the deceased donor organ donation procedure leading to organ allocation via the French Biomedicine Agency. The improved resolution achieved with our protocol enhances the security of organ allocation, particularly benefiting highly sensitized recipients who often present intricate HLA antibody profiles. By overcoming technical challenges and providing comprehensive genotyping data, this approach holds the potential to significantly impact deceased donor HLA genotyping, thereby facilitating optimal organ allocation strategies.

Patterns in the distribution and directional asymmetry of fleas living on the northern white-breasted hedgehog Erinaceus roumanicus.

Fleas infecting northern white-breasted hedgehogs, Erinaceus roumanicus (Barrett-Hamilton), collected from 2009-2011 in Budapest (Hungary) were studied. A total of 305 white-breasted hedgehogs were captured and 1,251 fleas were collected. The flea community comprised two species, the hedgehog flea Archaeopsylla erinacei (Bouche, 1835) and the dog flea Ctenocephalides canis (Curtis, 1826), although the latter was only found on three hedgehogs. Fleas were found on half of the host specimens (51%; n = 156) where their distribution was strongly aggregated. The sex ratio of A. erinacei was biased towards females and was correlated with host size. Interestingly, the sex ratio of fleas became more equal on heavier hosts. It had been expected that, under high competition, the sex ratio would be female biased because it is known that female ectoparasites dominate on poorer hosts. The body size of a random sample of 200 fleas (100 female and 100 male) was measured under a microscope. The analyses showed directional asymmetry in two features - the distance between the top of the head and the eye, and head length. In this two body traits the left side was significantly greater than right side in both sexes of A. erinacei. Our data shed light on the complex nature of the flea population infecting northern white-breasted hedgehogs in an urban area.

Application of High-Throughput Next-Generation Sequencing for HLA Typing on Buccal Extracted DNA: Results from over 10,000 Donor Recruitment Samples.

BACKGROUND: Unambiguous HLA typing is important in hematopoietic stem cell transplantation (HSCT), HLA disease association studies, and solid organ transplantation. However, current molecular typing methods only interrogate the antigen recognition site (ARS) of HLA genes, resulting in many cis-trans ambiguities that require additional typing methods to resolve. Here we report high-resolution HLA typing of 10,063 National Marrow Donor Program (NMDP) registry donors using long-range PCR by next generation sequencing (NGS) approach on buccal swab DNA. METHODS: Multiplex long-range PCR primers amplified the full-length of HLA class I genes (A, B, C) from promotor to 3' UTR. Class II genes (DRB1, DQB1) were amplified from exon 2 through part of exon 4. PCR amplicons were pooled and sheared using Covaris fragmentation. Library preparation was performed using the Illumina TruSeq Nano kit on the Beckman FX automated platform. Each sample was tagged with a unique barcode, followed by 2×250 bp paired-end sequencing on the Illumina MiSeq. HLA typing was assigned using Omixon Twin software that combines two independent computational algorithms to ensure high confidence in allele calling. Consensus sequence and typing results were reported in Histoimmunogenetics Markup Language (HML) format. All homozygous alleles were confirmed by Luminex SSO typing and exon novelties were confirmed by Sanger sequencing. RESULTS: Using this automated workflow, over 10,063 NMDP registry donors were successfully typed under high-resolution by NGS. Despite known challenges of nucleic acid degradation and low DNA concentration commonly associated with buccal-based specimens, 97.8% of samples were successfully amplified using long-range PCR. Among these, 98.2% were successfully reported by NGS, with an accuracy rate of 99.84% in an independent blind Quality Control audit performed by the NDMP. In this study, NGS-HLA typing identified 23 null alleles (0.023%), 92 rare alleles (0.091%) and 42 exon novelties (0.042%). CONCLUSION: Long-range, unambiguous HLA genotyping is achievable on clinical buccal swab-extracted DNA. Importantly, full-length gene sequencing and the ability to curate full sequence data will permit future interrogation of the impact of introns, expanded exons, and other gene regulatory sequences on clinical outcomes in transplantation.

Technical Evaluation: Identification of Pathogenic Mutations in PKD1 and PKD2 in Patients with Autosomal Dominant Polycystic Kidney Disease by Next-Generation Sequencing and Use of a Comprehensive New Classification System.

Genetic testing of PKD1 and PKD2 is expected to play an increasingly important role in determining allelic influences in autosomal dominant polycystic kidney disease (ADPKD) in the near future. However, to date, genetic testing is not commonly employed because it is expensive, complicated because of genetic heterogeneity, and does not easily identify pathogenic variants. In this study, we developed a genetic testing system based on next-generation sequencing (NGS), long-range polymerase chain reaction, and a new software package. The new software package integrated seven databases and provided access to five cloud-based computing systems. The database integrated 241 polymorphic nonpathogenic variants detected in 140 healthy Japanese volunteers aged >35 years, who were confirmed by ultrasonography as having no cysts in either kidney. Using this system, we identified 60 novel and 30 known pathogenic mutations in 101 Japanese patients with ADPKD, with an overall detection rate of 89.1% (90/101) [95% confidence interval (CI), 83.0%-95.2%]. The sensitivity of the system increased to 93.1% (94/101) (95% CI, 88.1%-98.0%) when combined with multiplex ligation-dependent probe amplification analysis, making it sufficient for use in a clinical setting. In 82 (87.2%) of the patients, pathogenic mutations were detected in PKD1 (95% CI, 79.0%-92.5%), whereas in 12 (12.8%) patients pathogenic mutations were detected in PKD2 (95% CI, 7.5%-21.0%); this is consistent with previously reported findings. In addition, we were able to reconfirm our pathogenic mutation identification results using Sanger sequencing. In conclusion, we developed a high-sensitivity NGS-based system and successfully employed it to identify pathogenic mutations in PKD1 and PKD2 in Japanese patients with ADPKD.

Identification of Hepatozoon erhardovae Krampitz, 1964 from bank voles (Myodes glareolus) and fleas in Southern Hungary.

In order to investigate the prevalence and life cycle of apicomplexan parasites, small mammals were live-trapped with modified Sherman traps in Southern Hungary between 2010 and 2012. Altogether, 528 rodents (Apodemus flavicollis Melchior, 1834, Apodemus agrarius Pallas, 1771, Myodes glareolus Schreber, 1780, Microtus agrestis Linnaeus, 1761, Mus musculus Linnaeus, 1758 and Micromys minutus Pallas, 1771) were collected and four shrews (Sorex spp.) were by-catched. Captured animals belonging to non-protected species were euthanized, and spleen samples were preserved for histological and molecular analyses. During the examination of spleen smears, Hepatozoon parasites were observed in eight out of 48 bank voles (M. glareolus). DNA was isolated from altogether 221 spleen samples, and 18S rDNA was amplified using two different PCR protocols. The eight bank vole samples were positive with PCR, but none of the other M. glareolus spleen samples or any of the tissue samples from other species were found to be infected. Sequenced amplicons were very similar to Hepatozoon spp. detected in M. glareolus in Spain and Poland. Ectoparasites were collected from the small mammal carcasses and from the vegetation. Hepatozoon DNA was not found in the 181 ticks removed from the small mammals or in the 162 ticks collected with flagging, but was detected in all three flea species (4/43 Megabothris turbidus Rothschild, 1909, 3/10 Ctenophthalmus assimilis Taschenberg, 1880 and 7/78 Ctenophthalmus agyrtes Heller, 1896). Based on gamont morphology, vertebrate and arthropod host species and DNA sequences, the parasites in our study can be identified as Hepatozoon erhardovae.

Prevalence and diversity of human pathogenic rickettsiae in urban versus rural habitats, Hungary.

Tick-borne rickettsioses belong to the important emerging infectious diseases worldwide. We investigated the potential human exposure to rickettsiae by determining their presence in questing ticks collected in an urban park of Budapest and a popular hunting and recreational forest area in southern Hungary. Differences were found in the infectious risk between the two habitats. Rickettsia monacensis and Rickettsia helvetica were identified with sequencing in questing Ixodes ricinus, the only ticks species collected in the city park. Female I. ricinus had a particularly high prevalence of R. helvetica (45%). Tick community was more diverse in the rural habitat with Dermacentor reticulatus ticks having especially high percentage (58%) of Rickettsia raoultii infection. We conclude that despite the distinct eco-epidemiological traits, the risk (hazard and exposure) of acquiring human pathogenic rickettsial infections in both the urban and the rural study sites exists.

Eco-epidemiology of Borrelia miyamotoi and Lyme borreliosis spirochetes in a popular hunting and recreational forest area in Hungary.

BACKGROUND: Borrelia miyamotoi, the newly discovered human pathogenic relapsing fever spirochete, and Borrelia burgdorferi sensu lato are maintained in natural rodent populations. The aim of this study was to investigate the natural cycle of B. miyamotoi and B. burgdorferi s.l. in a forest habitat with intensive hunting, forestry work and recreational activity in Southern Hungary. METHODS: We collected rodents with modified Sherman-traps during 2010-2013 and questing ticks with flagging in 2012. Small mammals were euthanized, tissue samples were collected and all ectoparasites were removed and stored. Samples were screened for pathogens with multiplex quantitative real-time polymerase chain reaction (qPCR) targeting a part of flagellin gene, then analysed with conventional PCRs and sequencing. RESULTS: 177 spleen and 348 skin samples of six rodent species were individually analysed. Prevalence in rodent tissue samples was 0.2 % (skin) and 0.5 % (spleen) for B. miyamotoi and 6.6 % (skin) and 2.2 % (spleen) for B. burgdorferi s.l. Relapsing fever spirochetes were detected in Apodemus flavicollis males, B. burgdorferi s.l. in Apodemus spp. and Myodes glareolus samples. Borrelia miyamotoi was detected in one questing Ixodes ricinus nymph and B. burgdorferi s.l in nymphs and adults. In the ticks removed from rodents DNA amplification of both pathogens was successful from I. ricinus larvae (B. miyamotoi 5.6 %, B. burgdorferi s.l. 11.1 %) and one out of five nymphs while from Ixodes acuminatus larvae, and nymph only B. burgdorferi s.l. DNA was amplified. Sequencing revealed B. lusitaniae in a questing I. ricinus nymph and altogether 17 B. afzelii were identified in other samples. Two Dermacentor marginatus engorged larva pools originating from uninfected hosts were also infected with B. afzelii. CONCLUSIONS: This is the first report of B. miyamotoi occurrence in a natural population of A. flavicollis as well as in Hungary. We provide new data about circulation of B. burgdorferi s.l. in rodent and tick communities including the role of I. acuminatus ticks in the endophilic pathogen cycle. Our results highlight the possible risk of infection with relapsing fever and Lyme borreliosis spirochetes in forest habitats especially in the high-risk groups of hunters, forestry workers and hikers.

Synanthropic rodents and their ectoparasites as carriers of a novel haemoplasma and vector-borne, zoonotic pathogens indoors.

BACKGROUND: Despite their close association with human dwellings, the role of synanthropic rodents in the epidemiology of vector-borne infections is seldom studied. The aim of the present study was to compensate for this lack of information, by the molecular investigation of vector-borne bacteria in peridomestic rodents and their ectoparasites. FINDINGS: Fifty-two rodents (mainly house mice and brown rats) were caught alive in buildings and checked for blood-sucking ectoparasites; followed by molecular analysis of these, together with spleen samples, for the presence of vector-borne agents. Haemoplasma infection was significantly more prevalent among brown rats, than among house mice. A novel haemoplasma genotype (with only 92-93% similarity to Candidatus Mycoplasma turicensis and M. coccoides in its 16S rRNA gene) was detected in a harvest mouse and a brown rat. Sporadic occurrence of Rickettsia helvetica, Anaplasma phagocytophilum, Borrelia burgdorferi s.l. and Bartonella sp. was also noted in rodents and/or their ectoparasites. CONCLUSIONS: These results indicate that synanthropic rodents, although with low prevalence, may carry zoonotic and vector-borne pathogens indoors.

A 4-year study of a natural tick-borne encephalitis virus focus in Hungary, 2010-2013.

A tick-borne encephalitis virus focus was identified in a former goat pasture that had been associated with a milk-borne encephalitis outbreak in 2007. Ticks and rodents were sampled monthly from April 2010 to October 2013 on two separate 0.5 ha sampling sites. At site 1, three tick-borne encephalitis virus strains were isolated from a total of 7,247 sampled ticks; 28 of the 539 tested sera (5.19%) were seropositive. At site 2, from the 2,369 sampled ticks, virus was not isolated, tests of 284 rodent sera resulted in 14 positives (4.93%). For survival, the virus needs a territory with continuously dense rodent and tick population, although observed TBEV prevalence was low both in ticks and in rodents. Sampling points of positive ticks and rodents did not coincided exactly, at a certain time only some m(2) territory is dangerous, these hot spots change unpredictably as positive ticks die or move on with their hosts.

Candidatus Neoehrlichia mikurensis and Anaplasma phagocytophilum in natural rodent and tick communities in Southern Hungary.

The aim of this study was to investigate the natural cycle of the new human pathogenic bacteria Candidatus Neoehrlichia mikurensis and Anaplasma phagocytophilum in Southern Hungary. We collected rodents with live-traps (2010-2013) and questing ticks with flagging in 2012. Small mammals were euthanized, tissue samples were collected and all the ectoparasites were removed and stored in 70% alcohol. We found relatively low overall prevalence of tick infestation (8%). Samples were analysed for A. phagocytophilum and Candidatus N. mikurensis with multiplex quantitative real-time PCR targeting a part of major surface protein 2 (msp2) and the heat shock protein groEL genes, respectively. The overall prevalence in tissue samples was 6.6% (skin) and 5.1% (spleen) for A. phagocytophilum and 1.7% (skin) and 3.4% (spleen) for Candidatus N. mikurensis. Candidatus N. mikurensis was only detected in Apodemus flavicollis and Apodemus agrarius, while A. phagocytophilum was found in A. flavicollis, A. agrarius, Myodes glareolus, Microtus arvalis and Mus musculus samples. Prevalence of A. phagocytophilum in skin samples of A. flavicollis was significantly higher than prevalence of N. mikurensis (p<0.05). Among questing Ixodes ricinus ticks we found three (8.8%) individuals (female, male, nymph) infected with Candidatus N. mikurensis. Five (3.1%) questing ticks had A. phagocytophilum infection (one I. ricinus male, two Dermacentor reticulatus females and two Haemaphysalis concinna females). We found one I. ricinus nymph removed from a male A. flavicollis with A. phagocytophilum infection. Our study provides new data on the occurrence of these pathogens in rodent tissue samples, questing ticks and engorged ticks in Southern Hungary.

Vector-borne agents detected in fleas of the northern white-breasted hedgehog.

This is the first large-scale molecular investigation of fleas from a geographically widespread and highly urbanized species, the northern white-breasted hedgehog. In this study, 759 fleas (the majority were Archaeopsylla erinacei) collected from 134 hedgehogs were molecularly analyzed individually or in pools for the presence of three groups of vector-borne pathogens. All flea samples were positive for rickettsiae: In two samples (1.5%) Rickettsia helvetica and in 10% of the others a novel rickettsia genotype were identified. Additionally, Bartonella henselae (the causative agent of cat scratch disease in humans) was demonstrated in one flea (0.7%), and hemoplasmas of the hemofelis group were identified in seven other samples (5.2%). The findings of vector-borne agents not detected before in A. erinacei fleas broaden the range of those diseases of veterinary-medical importance, of which hedgehogs may play a role in the epidemiology.

HLA typing from 1000 genomes whole genome and whole exome illumina data.

Specific HLA genotypes are known to be linked to either resistance or susceptibility to certain diseases or sensitivity to certain drugs. In addition, high accuracy HLA typing is crucial for organ and bone marrow transplantation. The most widespread high resolution HLA typing method used to date is Sanger sequencing based typing (SBT), and next generation sequencing (NGS) based HLA typing is just starting to be adopted as a higher throughput, lower cost alternative. By HLA typing the HapMap subset of the public 1000 Genomes paired Illumina data, we demonstrate that HLA-A, B and C typing is possible from exome sequencing samples with higher than 90% accuracy. The older 1000 Genomes whole genome sequencing read sets are less reliable and generally unsuitable for the purpose of HLA typing. We also propose using coverage % (the extent of exons covered) as a quality check (QC) measure to increase reliability.

Transmission of Rickettsia slovaca and Rickettsia raoultii by male Dermacentor marginatus and Dermacentor reticulatus ticks to humans.

We analyzed rickettsial DNA of ticks from tick-borne lymphadenopathy (TIBOLA) patients. Dermacentor marginatus (9/17) and Dermacentor reticulatus (8/17) transmitted rickettsiae to a similar extent. Rickettsia raoultii was detected in more ticks than Rickettsia slovaca. We observed the development of TIBOLA symptoms after the bite of males of both tick species.

Ticks and the city: ectoparasites of the Northern white-breasted hedgehog (Erinaceus roumanicus) in an urban park.

The European hedgehog (Erinaceus europaeus) is known to host several ectoparasites and also tick-borne pathogens, but there is scant information on its eastern relative, the Northern white-breasted hedgehog (Erinaceus roumanicus). We have studied an urban population of E. roumanicus in a city park of central Budapest, Hungary, for 2 years to investigate their tick and flea species. A total of 5063 ticks and 818 fleas were collected from 247 hedgehogs (including 46 recaptures). Ectoparasite prevalence and intensity differed significantly (p<0.001) between the 2 study years attributable to the enhanced tick removal rate due to anaesthesia used in the second year. The most common tick species was Ixodes ricinus (93.7%) followed by unidentified Ixodes larvae (5%). Only 57 hedgehog ticks (I. hexagonus) were removed from 22 hedgehogs. One I. acuminatus and one Hyalomma marginatum nymph were also collected. Mean intensity of tick infestation was 26.5 (range: 0-155 ticks/host) and mean intensity of flea infestation was 6.6 (range: 0-78 fleas/host). Most fleas (99.4%) collected were hedgehog fleas (Archaeopsylla erinacei), dog fleas (Ctenocephalides canis) were found on 2 hedgehogs. Hyalomma marginatum has previously not been found in Hungary, and I. acuminatus was only reported sporadically before. The large number of ectoparasites and the 2 imported tick species may thus survive in close proximity to humans if hedgehogs are present. This calls attention to the risk of possible tick-borne human infections that urban hedgehogs can pose.

Detection of Borrelia burgdorferi Sensu Lato and Anaplasma phagocytophilum in small mammals and ectoparasites in Hungary.

The aim of our study was to investigate the presence of Borrelia burgdorferi sensu lato (s.l.) and Anaplasma phagocytophilum in small mammals and ticks using polymerase chain reaction and to gain information about the prevalence and possible coexistence of these pathogens at a selected site in Hungary. Two hundred seventy-seven small mammals were trapped in South-Eastern Hungary during 2009. Tissue samples and a total of 831 ectoparasites (Ixodes ricinus, Ixodes acuminatus, Haemaphysalis concinna, Ctenophtalmus assimilis, and Nosopsyllus fasciatus) were collected from small mammals. One thousand one hundred and six I. ricinus and 476 H. concinna were collected from the vegetation during the investigation. Neither A. phagocytophilum nor B. burgdorferi s.l. was detected in any of the mammal tissue samples. A. phagocytophilum was not found in ticks collected from small mammals. Very low minimum prevalence was found for all pathogens (0.62% for Borrelia afzelii in ticks collected from small mammals, and 0.57%, 0.06%, and 0.19% for A. phagoctyophilum, B. afzelii, and Borrelia garinii, respectively, in questing ticks). The present study is the first report of borreliae from I. acuminatus and H. concinna from Hungary.

Investigation of the ecology of Francisella tularensis during an inter-epizootic period.

A 1-year study of the ecological cycle of Francisella tularensis was performed in an enzootic area during an inter-epizootic period. The study was based on multiple sampling of all major constituents of the disease cycle. Seroprevalence of tularemia in the European brown hare (Lepus europaeus) population was 5.1% (10/197) with low antibody titers (1/10 and 1/20), and F. tularensis ssp. holarctica was isolated from four hares. F. tularensis was not detected in the 38 common voles (Microtus arvalis), 110 yellow-necked mice (Apodemus flavicollis), or 15 stripped field mice (Apodemus agrarius) trapped during the study, or the by-catch of 8 Eurasian pygmy shrews (Sorex minutus) or 6 common shrews (Sorex araneus). A total of 1106 Ixodes ricinus and 476 Haemaphysalis concinna ticks were collected from vegetation, and 404 I. ricinus, 28 H. concinna ticks, and 15 Ctenophtalmus assimilis and 10 Nosopsyllus fasciatus fleas were combed off small mammals. One H. concinna female and one nymph collected from the vegetation was found infected with F. tularensis ssp. holarctica by TaqMan polymerase chain reaction, thus resulting a 0.42% (2/476) prevalence. F. tularensis-specific DNA was not detected in environmental water samples, and the examined 100 sheep, 50 cows, and 50 buffalos grazed at the study area were all seronegative. During inter-epizootic periods, F. tularensis ssp. holarctica seems to persist only in the European brown hare--H. concinna cycle at the studied habitat. H. concinna may not serve exclusively as an arthropod vector, but it may also harbor bacteria for 3-4 years through multiple life stages and act as an important reservoir of F. tularensis. Rodent species probably do not serve as true reservoir hosts of tularemia.

Susceptibility of the common hamster (Cricetus cricetus) to Francisella tularensis and its effect on the epizootiology of tularemia in an area where both are endemic.

Francisella tularensis is a highly infectious zoonotic agent causing the disease tularemia. The common hamster (Cricetus cricetus) is considered a pest in eastern Europe, and believed to be a source of human tularemia infections. We examined the role of the common hamster in the natural cycle of tularemia using serologic methods on 900 hamsters and real-time polymerase chain reaction (PCR) on 100 hamsters in an endemic agricultural area. We collected 374 Ixodes acuminatus ticks from the hamsters and tested them by real-time PCR. All tests were negative. To examine clinical signs, pathology, and histopathology of acute tularemia infection similar to the natural infection, two hamsters were infected with a large dose of a wild strain of F. tularensis ssp. holarctica. After a short period of apathy, the animals died on the eighth and ninth days postinfection. The pathologic, histopathologic, and immunohistochemical examination contributed to the diagnosis of septicemia in both cases. Our results confirmed previous findings that common hamsters are highly sensitive to F. tularensis. We conclude that although septicemic hamsters may pose substantial risk to humans during tularemia outbreaks, hamsters in interepizootic periods do not act as a main reservoir of F. tularensis.

Detection of Borrelia burgdorferi sensu lato in lizards and their ticks from Hungary.

To investigate the involvement of lizard species in the natural cycle of Borrelia burgdorferi sensu lato (s.l.) in Hungary, a total of 186 reptiles belonging to three species--126 green lizards (Lacerta viridis), 40 Balkan wall lizards (Podarcis taurica), and 20 sand lizards (Lacerta agilis)--were captured in 2007 and 2008. All ticks removed from the lizards were Ixodes ricinus, either larvae (324/472; 68.6%) or nymphs (148/472; 31.4%). More than half (66/126; 52.4%) of L. viridis individuals were infested, and the prevalence of tick infestation on both the other two species was 35% each. All 472 I. ricinus ticks and tissue samples collected from 134 collar scales and 62 toe clips of lizards were further analyzed for the presence of B. burgdorferi s.l. with polymerase chain reaction. The amplification of B. burgdorferi s.l. DNA was successful in 8% (n = 92) of L. viridis, 9% (n = 32) of P. taurica, and 10% (n = 10) of L. agilis tissue samples. Restriction fragment length polymorphism genotyping identified the species Borrelia lusitaniae in all tested lizard samples. Prevalence of B. burgdorferi s.l. in ticks collected from L. viridis, P. taurica, and L. agilis was 8%, 2%, and 0%, respectively. Most of the infected ticks carried B. lusitaniae (74% of genotyped positives); however, Borrelia afzelii (5%) and B. burgdorferi sensu stricto (21%) were detected in ticks removed from green lizards and Balkan wall lizards, respectively. We conclude that lizards, particularly L. viridis, can be important hosts for I. ricinus larvae and nymphs; thus, they can be regarded as reservoirs of these important pathogen vectors. The role of green lizards has been confirmed, and the implication of Balkan wall lizards is suggested in the natural cycle of B. lusitaniae at our study site.

Diversity of polyketide synthase gene sequences in Aspergillus species.

Fungal polyketide synthases are responsible for the biosynthesis of several mycotoxins and other secondary metabolites. The aim of our work was to investigate the diversity of polyketide synthases in Aspergillus species using two approaches: PCR amplification using oligonucleotide primers, and bioinformatics. Ketosynthase domain probes amplified DNA fragments of about 700 bp in each examined isolate. Sequences of these domains were aligned and analyzed by phylogenetic methods. The ketosynthase domain sequences were highly diverse indicating that they most probably represent polyketide synthases responsible for different functions. A. albertensis and A. niger ketosynthase domain sequences clustered together with sequences of genes required for pigment biosynthesis (wA) in A. nidulans and P. patulum, while the ketosynthase domain sequence of A. muricatus was most closely related to an A. parasiticus wA type domain sequence, and those of the A. ochraceus isolates formed a distinct clade on the tree. These sequences were highly homologous to an A. terreus naphthopyrone synthase gene. An Aspergillus fumigatus genomic database was also searched for ketosynthase domain sequences, which have been included in the phylogenetic analysis. Altogether 14 putative ketosynthase domain sequences were identified. Clustering of the ketosynthase domain sequences correlated well with the type of metabolites produced by the corresponding polyketide synthases. At least 8 clusters with putative ketosynthase domain sequences of unknown function have been identified. Further studies are in progress to clarify the role of some of the identified polyketide synthase genes.