Genetic characterization of parvoviruses circulating in turkey and chicken flocks in Poland

Between 2008 and 2011, commercial turkey and chicken flocks in Poland were examined for the presence of turkey parvovirus (TuPV) and chicken parvovirus (ChPV). Clinical samples (10 individual faecal swabs/flock) from 197 turkey flocks (turkeys aged 1 to 19 weeks) and 45 chicken flocks (chickens aged 3 to 17 weeks) were collected in different regions of the country and tested using a PCR assay that targeted the NS1 gene (3’ORF). The prevalence of TuPV was 29.4 % in the flocks tested, while ChPV infections were found in 22.2 % of the studied flocks. Phylogenetic analysis revealed a clear division into three groups: ChPV-like, TuPV-like and a third, previously unrecognized and distinct subgroup, TuPV-LUB, containing exclusively three Polish isolates from turkeys. The isolates from the novel group showed as little as 50.6-64.5 % of nucleotide sequence identity to the prototype chicken and turkey parvovirus strains. Genetic analysis of a ChPV isolate that was classified in the TuPV group strongly suggests a recombination event between chicken and turkey parvoviruses

An avian influenza H5N1 virus vaccine candidate based on the extracellular domain produced in yeast system as subviral particles protects chickens from lethal challenge

AbstractHighly pathogenic avian influenza is an on-going problem in poultry and a potential human pandemic threat. Pandemics occur suddenly and vaccine production must be fast and effective to be of value in controlling the spread of the virus. In this study we evaluated the potential of a recombinant protein from the extracellular domain of an H5 hemagglutinin protein produced in a yeast expression system to act as an effective vaccine. Protein production was efficient, with up to 200 mg purified from 1 L of culture medium. We showed that the deletion of the multibasic cleavage site from the protein improves oligomerization and, consequentially, its immunogenicity. We also showed that immunization with this deleted protein protected chickens from challenge with a highly pathogenic avian influenza H5N1 virus. Our results suggest that this recombinant protein produced in yeast may be an effective vaccine against H5N1 virus in poultry

One-year molecular survey of astrovirus infection in turkeys in Poland

The presence of turkey astrovirus (TAstV) was monitored in meat-type turkey flocks in Poland in 2008. Clinical samples (10 individual faecal swabs/flock) from 77 flocks aged 1-19 weeks were collected from different regions of the country. RT-PCR experiments were performed for detection and molecular characterization of TAstV using four sets of primers within the RdRp gene (ORF1b). The prevalence of astrovirus was 34/77 (44.15%) in the flocks tested. TAstV type 2 was associated with 30 of 77 infections (38.9%), either alone or in mixed infections; TAstV type 1 was detected in 9 of 77 flocks (11.6%), either alone or in mixed infections; ANV was detected only in one flock (1.29%) by sequence analysis during this study. Phylogenetic analysis revealed genetic variability in the TAstV strains that were isolated. Some of Polish TAstV-2 strains were genetically related to the North American isolates; however, most of them formed a distinct subgroup of “European” isolates, suggesting their separate origin or evolution. Additionally, due to the high variability of the TAstV sequences, the most suitable method for TAstV typing seems to be sequencing

Highly Pathogenic Avian Influenza Virus (H5N1) in Frozen Duck Carcasses, Germany, 2007

Article summary line: Phylogenetic and epidemiologic evidence shows incursion of HPAIV into the food chain

Avian influenza in Poland

Poland has experienced four episodes of avian influenza (AI) outbreaks over the past two decades. The first epidemic was caused by a low pathogenicity (LPAIV) H7N7 subtype and occurred in fattening and breeder turkeys in 1995. Two waves of H5N1 high pathogenicity avian influenza (HPAI) took place in 2006 and 2007. In spring 2006, 64 cases of the H5N1 virus were detected, mostly in mute swans. In December 2007, ten outbreaks of H5N1 HPAI were detected in commercial poultry (n=9) and wild birds kept in captivity (n=1). The outbreaks in 2006 and 2007 were caused by genetically similar but clearly distinguishable viruses of the 2.2 clade. In 2013, an H9N2 avian influenza virus was detected in 4 fattening turkey holdings. The virus was low pathogenic and a phylogenetic study has shown a close relatedness to the Eurasian lineage of AIV of the wild bird origin. Neither preventive nor prophylactic vaccinations have ever been used in poultry or other birds. Emergency vaccinations using autogenous vaccine were introduced only to control the H7N7 LPAI outbreaks in 1995. The baseline surveillance for AI in live migratory birds and poultry provides a valuable insight into the ecology of AIV at the wild and domestic bird interface. Passive surveillance is in place of early detection of HPAIV infection in dead or moribund birds

Phylogenetic studies of H3 low pathogenic avian influenza viruses isolated from wild mallards in Poland

In order to study the variation of low pathogenic avian influenza viruses (AIV) of H3 subtype in the natural reservoir, partial genetic characterisation of four AIV isolates of H3 subtype, recovered from wild mallards in Poland in 2006–2010, was performed. Phylogenetic analysis clearly confirms that there is a constant flow of AIV H3 between wild birds in Eurasia and Africa, and, to a limited degree, to North America (Alaska), with an occasional spill-over to poultry. The analysis of the PA gene of one isolate from 2010 suggests that it is closely related to several HPAI H5N1 viruses belonging to clade 2.3.2 and that, therefore, a reassortment event has occurred recently between low pathogenic and H5N1 highly pathogenic AIV

Detection of Newcastle Disease Virus Minor Genetic Variants by Modified Single-Stranded Conformational Polymorphism Analysis

Newcastle disease and Avian Influenza are considered to be the most dangerous fowl diseases which may cause huge economic losses. Newcastle disease is caused by the enveloped, and single-stranded RNA virus (NDV, APMV-1; belonging to Paramyxoviridae family), which can be further divided into sixteen different genotypes grouped into five pathotypes according to their pathogenicity. It has been reported that low pathogenic virus can greatly increase its pathogenicity even during a single passage. Additionally, due to the widespread use of live vaccines, a mixture of two or more different viruses in one sample can be detected. Hence, there is a great need for establishment of fast, inexpensive, sensitive, and relatively simple diagnostic method for multistrain and quasispecies detection of NDV infection. In this paper we describe a diagnostic method based on RT-PCR followed by a modified version of single-stranded conformational polymorphism analysis using short DNA fragments of gene encoding viral F protein. The method allows for rapid diagnosis of genetic variant emerging from previously stable population which may prevent the spread of the pathogenic viral variant

Active surveillance in poultry in Poland for avian influenza subtypes H5 and H7

A serological surveillance programme for avian influenza A virus (AIV) subtype H5 and H7 in poultry was implemented in Poland in 2008-2013 with two main objectives: i) to detect subclinical infections or previous exposures to AIV H5 and H7 subtypes and ii) to demonstrate the AI- free status of Poland. During this period, over 45 000 serum samples from 2833 holdings were examined using the hemagglutination inhibition test (HI). The presence of HI antibodies was detected in 8 breeder geese holdings (7 positive for H5 and 1 positive for H7 AIV) and in 1 breeder duck holding (H5-positive), which represented 0.32% of all investigated holdings. All seropositive flocks were examined by real time RT-PCR with negative results, which substantiated the AI-free status of Poland. Positive results detected in clinically healthy poultry kept in an open range system indicate prior infections with low pathogenic AIV originating from the wild-bird reservoir

Detection and differentiation of Newcastle disease virus and influenza virus by using duplex real-time PCR

Newcastle disease virus (NDV), member of the Paramyxoviridae family and avian influenza virus (AIV), member of the Orthomyxoviridae family, are two main avian pathogens causing serious economic problems in poultry health. Both are enveloped, single-stranded, negative-sense RNA viruses and cause similar symptoms, ranging from sub-clinical infections to severe diseases, including decrease in egg production, acute respiratory syndrome, and high mortality. Similar symptoms hinder the differentiation of infection with the two viruses by standard veterinary procedures like clinical examination or necropsy. To overcome this problem, we have developed a new duplex real-time PCR assay for the detection and differentiation of these two viruses. Eighteen NDV strains, fourteen AIV strains, and twelve other (negative control) strains viruses were isolated from allantoic fluids of specific pathogen-free (SPF), embryonated eggs. Four-weeks-old SPF chickens were co-infected with both viruses (NDV - LaSota and AIV - H7N1). Swabs from cloaca and trachea were collected and examined. The results obtained in this study show that by using duplex real-time PCR, it was possible to detect and distinguish both viruses within less than three hours and with high sensitivity, even in case a bird was co-infected. Additionally, the results show the applicability of the real-time PCR assay in laboratory practice for the identification and differentiation of Newcastle disease and influenza A viruses in birds