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Extremly high viremia is observed during some viruses infection, especialy in immunocompromised patients. False negative results of Parvovirus B19 DNA tests performed with real-time PCR in high viremic samples are reported. The way of fluorescence diagrams analysis and algorithm of positive result confirmation to exclude such phenomenon are proposed.
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Viral infections in goose flocks in Poland

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The aim of this study was to determine the infectious agents isolated from infection - suspected geese sent for the diagnostic examination to National Veterinary Research Institute. The birds were sent from goose flocks localized in different parts of Poland. Totally, 1,013 birds from 122 flocks were examined. The presence of goose parvovirus (GPV), goose haemorrhagic polyomavirus (GHPV), and goose circovirus (GoCV) was detected by triplex PCR. The presence of GPV DNA was shown in 36 flocks. The disease was most frequently diagnosed in goslings aging 3.5 weeks (ten flocks), and 2.5 weeks (six flocks). The analysis of the nucleotide sequence of VP1 encoding region has shown close similarity of Polish GPV strains within the group which ranged from 92% to 100%. Moreover, the similarity level of these strains with GPV isolated in Europe was from 91.3% to 100%. The occurrence of GoCV DNA was shown in 25 goose flocks. The presence of GoCV DNA was found among geese aged from 2 to 6 weeks, but predominantly in those aging 3.5 (three flocks) and 5 weeks (five flocks). The sequence analysis of PCR products from the sequenced region of ORFC1 capsid protein of GoCV has shown that Polish isolates share from 85% to 91% similarity with the sequences of GoCV strains isolated in other countries. The presence of DNA of GHPV was found in 3-week-old geese. During the last 2 years the presence of GHPV was confirmed in three flocks of goslings at the age from 3 to 3.5 weeks. During the last 12 years the occurrence of co-infection with GPV and GoCV was detected in six flocks aging from 5 to 6 weeks.
In our studies two primer pairs within the VP2 protein gene of canine parvovirus were chosen on the base of the sequence of Polish isolates. The sensitivity of detection of canine parvovirus in stool samples by Nested PCR was increased 60% in comparison with the standard PCR method and it was 30% higher than the virus isolation in tissue culture. A simple procedure of sample preparation with the use of Chelating resin was used and it made the Nested PCR easily applicable in rapid confirmation of the diagnosis of parvovirus infection.
The aim of this study was to come up with molecular characteristics of Polish strains of goose parvovirus (GPV) on the basis of genes encoding their structural proteins. Ten field GPV strains and two vaccine strains: B-38 and MFP were used. The PCR- RFLP method based on three distinct endonucleases: HinfI, MboI, and RsaI, which had restriction sites within the sequences of examined genes, was applied. It was found that the homology of VP1, VP2, and VP3 among the studied strains ranged from 50% to 100%. The major differences in restriction patterns were found after application of HinfI, whereas 100% homology was observed after Rsal digestion. Significant differences were observed in restriction profiles of vaccine GPV strains. The study revealed that the application of PCR-RFLP for the analysis of VP1, VP2, and VP3 genes allowed for their molecular characteristics and differentiation between the vaccine and field strains.
The presented study aimed at application of the PCR methods for the detection and differentiation of goose parvovirus (GPV) and Muscovy duck parvovirus (MDPV) in the liver, spleen, and faeces of infected geese and in litter from infected farms. For the improvement of specificity and efficiency of the methods, as well as for overcoming the frequent inhibition of PCR in samples extracted from faeces and litter, the "touchdown" thermal profile with additive of betaine were used. The isolation of the virus in goose embryo fibroblasts was used as a verifying method for GPV and MDPV detection. The presence of the cytopathic effect in infected cell cultures allowed for the detection of the both parvoviruses but not for their differentiation. As a result of this study, PCR methods for the fast detection of GPV and MDPV in field samples of visceral organs and faeces of infected geese and in their litter were developed.
The effect of composting and anaerobic fermentations under meso- and thermophylic conditions (37° and 55℃) on the survival of bovine parvovirus (BPV) and Aujeszky’s disease viruse (ADV) in meat wastes has been examined in this study. Viruses were adsorbed on filters and introduced into carriers which were made of meat fragments of different sizes and bones or in the form of suspension they were introduced into the biomass in the course of processes of waste treatment. Carriers were removed at appropriate time intervals and virus titres were determined. The thermoresistant parvovirus survived for the longest time during mesophylic fermentation (almost 70 days), slightly shorter during composting (7-9.5 days depending on the type of carrier) and for the shortest time – at 55℃ (46-76 hours). Its inactivation rate was the fastest in a suspension, slower in meat and bone carriers. ADV inactivation proceeded considerably faster, as compared with BPV. Its active particles were not detected as early as in the 30th minute of thermophylic fermentation, the 6th hour of mesophylic fermentation and at the first sampling time during composting (at the 72nd hour). Total survival time ranged from 50 min to 13 hours. All the tested technologies enabled the effective elimination of ADV and on average twofold decrease in BPV titre. From the study conducted it follows that of both viruses, the BPV should be applied for validation processes of methods used in meat waste processing, particularly if this refers to methods where higher temperature is the factor inactivating pathogens.
Sixteen field strains of goose parvovirus (GPV) and DNA extracted from standard strain of Muscovy duck parvovirus (MDPV) were used. PCR was used for the amplification of the VP3 structural protein encoding region. In the case of all GPV strains and one MDPV strain the presence of specific product about 1,604 bp long was observed. The essential conditions, which had the influence on the specificity, sensitivity, and efficiency of the amplification reaction, were optimised. In order to eliminate unspecific interactions between template and primers touchdown PCR was applied. Additionally, for specificity and efficiency improvement, betaine (N, N, N - trimethylglycine) was added. The conducted optimisation steps of PCR allowed for the identification of the both parvoviruses.
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The polymerase chain reaction (PCR) was used to demonstrate the presence of CPV DNA in tissue cultures and faecal suspensions. A simple procedure of sample preparation was elaborated and it made the PCR easily applicable in rapid confirmation of the diagnosis of parvovirus infection. The results of PCR were compared with virus isolation, haemagglutination and immunoenzymatic tests.
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