Réka Borzák

Zoonotic transmission of reassortant porcine G4P[6] rotaviruses in Hungarian pediatric patients identified sporadically over a 15 year period.

Genotype G4P[6] Rotavirus A (RVA) strains collected from children admitted to hospital with gastroenteritis over a 15 year period in the pre rotavirus vaccine era in Hungary were characterized in this study. Whole genome sequencing and phylogenetic analysis was performed on eight G4P[6] RVA strains. All these RVA strains shared a fairly conservative genomic configuration (G4-P[6]-I1/I5-R1-C1-M1-A1/A8-N1-T1/T7-E1-H1) and showed striking similarities to porcine and porcine-derived human RVA strains collected worldwide, although genetic relatedness to some common human RVA strains was also seen. The resolution of phylogenetic relationship between porcine and human RVA genes was occasionally low, making the evaluation of host species origin of individual genes sometimes difficult. Yet the whole genome constellations and overall phylogenetic analyses indicated that these eight Hungarian G4P[6] RVA strains may have originated by independent zoonotic transmission, probably from pigs. Future surveillance studies of human and animal RVA should go parallel to enable the distinction between direct interspecies transmission events and those that are coupled with reassortment of cognate genes.

Whole-genome sequencing of a green bush viper reovirus reveals a shared evolutionary history between reptilian and unusual mammalian orthoreoviruses

In this study, we sequenced the whole genome of a reovirus isolated from a green bush viper (Atheris squamigera). The bush viper reovirus shared several features with other orthoreoviruses, including its genome organization. In phylogenetic analysis, this strain was monophyletic with Broome virus and baboon orthoreovirus, indicating that these viruses might have originated from a common ancestor. These new molecular data supplement previous information based mainly on biological properties of reptilian reoviruses, confirming their taxonomic position and broadening our knowledge of the evolution of members of the genus Orthoreovirus.

Three new species of Myxobolus Bütschli, 1882 (Myxozoa: Myxobolidae) infecting the common nase Chondrostoma nasus (L.) in the River Danube

The common nase Chondrostoma nasus (L.) is a frequent cyprinid fish in the River Danube. In a survey on its infection with myxosporeans, eight different Myxobolus spp. spore types were found in the gills, swim bladder, fins and intestinal wall. Of these, spore types representing three species were studied in detail by morphological and molecular methods. Based on the differences in 18S rDNA sequences, two new species of Myxobolus Bütschli, 1882 from the gills and one from the swim bladder are described: M. arrabonensis n. sp., M. szentendrensis n. sp. and M. paksensis n. sp. The new species resembled M. muelleri Bütschli, 1882, M. intimus Zaika, 1965 and M.cycloides Gurley, 1893, all parasitic in leuciscine cyprinids, in spore size and location in the host, but exhibited differences in partial 18S rDNA sequences as follows: M. arrabonensis - M. muelleri (1.4%), M. szentendrensis - M. intimus (2.8%), M. paksensis - M. cycloides (2.4%). Based on the significant differences in rDNA sequences, the three forms are considered to represent new, hitherto undescribed species in spite of their morphological similarities to some Myxobolus spp. forming spores in identical locations in genetically closely related cyprinids of the subfamily Leuciscinae.

Molecular detection and genome analysis of circoviruses of European eel (Anguilla anguilla) and sichel (Pelecus cultratus)

The prevalence and distribution of piscine circoviruses (CVs) were tested in a routine virus monitoring programme in Lake Balaton, Hungary. A high prevalence of European eel CV (EeCV) was found in the apparently healthy eel population (35.5%). The copy number of the viral DNA in different organs was determined by quantitative real-time PCR. The results suggested that some eel specimens were in active viraemic status despite their asymptomatic condition. Furthermore, a novel, previously undescribed CV was also detected in eel and sichel samples. Full genome characterisation confirmed that the virus represents a novel EeCV species (EeCV-2). The genome contains an integrated eel chromosome-derived fragment, suggesting that the original host of the virus was the eel and it probably emerged subsequently in the sichel by host switching. In some samples, an additional, 1,111-nt-long circular ssDNA was also observed involving a CV-like stem-loop structure and an ORF showing homology to CV capsid protein genes, without any sign of a replication initiator protein sequence.

Myxobolus infection in the cornea of the roach (Rutilus rutilus) in Lake Balaton

Infection of the cornea in fishes by Myxobolus plasmodia is a common but still little known site preference of myxosporeans. A sporadic but striking infection in the cornea of the roach (Rutilus rutilus) was observed in Lake Balaton, Hungary. Relatively small, round plasmodia 250 to 500 μm in diameter developed in the dense connective tissue of the cornea. Morphological and molecular biological examination of spores collected from cysts in the cornea demonstrated that this infection is caused by Myxobolus fundamentalis, a species hitherto reported only from the cartilaginous gill arch of the roach. The 18S rDNA sequences of spores from the cornea showed 99.9% identity to the sequences of spores from the gill arch, and they also shared 99.9% identity with the sequences of triactinomyxon actinospores obtained from the oligochaete Isochaetides michaelseni.

Description of Henneguya jaczoi sp. n. (myxosporea, myxobolidae) from Perca fluviatilis (L.) (pisces, percidae) with some remarks on the systematics of Henneguya spp. of european fishes

A new Henneguya species, H. jaczoi sp. n., is described from perch (Perca fluviatilis) from Lake Balaton, Hungary. This species infects the palatal region of the fish, forming large plasmodia in the thickened caudal part of the buccal cavity and at the dorsal ends of the cartilaginous gill arches. The species differs from the gill-dwelling Henneguya species of perch and pike (Esox lucius) both morphologically and in molecular aspects. The authors conclude that the type species H. psorospermica Thélohan is a specific parasite of pike, while the species forming plasmodia in the gills of perch corresponds to H. texta Cohn, which was hitherto regarded as a synonym of H. psorospermica. Besides the above-mentioned species, H. creplini was frequently found in pikeperch (Sander lucioperca) and Volga pikeperch (Sander volgensis), but no Henneguya infection has been recorded in ruffe (Gymnocephalus cernua), which is a common percid fish of the lake and is known to be the type host species for H. creplini.

Description of two new species of Myxobolus Bütschli, 1892, M. peleci n. sp. and M. cultrati n. sp., detected during an intensive mortality of the sichel, Pelecus cultratus (L.) (Cyprinidae), in Lake Balaton, Hungary.

In the summer of 2014, mass mortality of the sichel, Pelecus cultratus (L.), was observed in Lake Balaton, Hungary. Parasitological examination conducted in the framework of a complete diagnostic survey revealed myxozoan infections. Two species of Myxobolus Bütschli, 1892 were found, one in the gill lamellae and another in the eyes. Following this mass mortality, 113 sichel specimens were examined during a 14-month period. Gill infection with scattered spores in the lamellae was found in 51 fish, while infection in the eyes was recorded in three specimens only. Based upon the morphological and molecular biological data the species from the gills is described here as Myxobolus peleci n. sp. and the species from the eye as M. cultrati n. sp. The 18S rDNA sequences of the two species proved that they differ from all known Myxobolus spp. with sequence data available in the GenBank database. Histological examinations revealed that the spores found in the gill lamellae were derived from plasmodia developing in and around the afferent branchial arteries of the gill arches. No mortality of sichel was recorded in 2015. Infection with these two Myxobolus spp. does not seem to play a role in the mortality of the host fish.