Five QX-like infectious bronchitis virus (IBV) strains, isolated from different field outbreaks and two reference IBV strains of known serotypes (M41 and 793/B), were used in the present study to investigate and compare their pathogenicity for 1-day-old specific pathogen free chickens. The ability of the strains to inhibit trachea epithelium ciliary activity, to induce immune response, to replicate and to cause histopathological lesions in designated organs was followed by repeated samplings during a period of 42 days post infection. Clear differences in pathogenicity and in organ distribution of the three serotypes were found. Strain 793/B had the least capacity to invade the investigated organs, while it produced a good humoral response as measured by enzyme-linked immunosorbent assay. The QX-like strains generally replicated to higher titres, although differences were found among the five strains in their pathogenicity and affinity for different organs. The Chinese isolate of QX-like virus caused the most severe lesions and induced the highest antibody titres. Severe kidney damage and dilatation of the oviduct were the prominent lesions that could be related to the QX-like IBV strains, although neither marked virus replication nor histopathological lesions were detected in the oviduct.

-A two years survey was undertaken to determine the occurrence of Acute Bee Paralysis Virus (ABPV) in field samples of adult bees and the parasitic mite Varroa destructor. To detect the viral nucleic acid we used polymerase chain reaction following reverse transcription (RT-PCR). We demonstrated the presence of ABPV RNA in 14 from 114 seemingly healthy colony samples collected from Hungarian honey bees. The investigation revealed that two third of the apiaries were infected with ABPV at a 12.2% infection rate. In seven other apiaries out of eight investigated (87.5%) the presence of the virus was detected from colonies following a sudden collapse; these colonies were simultaneously infected with Nosema apis or infested with Varroa destructor. Virus specific nucleic acid was also identified in the mites collected from two apiaries falling into the latter category. The amplicon of RT-PCR was sequenced and the nucleic acid sequence was aligned to the complete ABPV sequence deposited in the GeneBank database revealing a 93% homology. acute bee paralysis virus / polymerase chain reaction / Varroa destructor / Nosema apis / honey bee

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