Tomasz Stenzel

Pigeon circoviruses display patterns of recombination, genomic secondary structure and selection similar to those of beak and feather disease viruses

Pigeon circovirus (PiCV) has a ~2 kb genome circular ssDNA genome. All but one of the known PiCV isolates have been found infecting pigeons in various parts of the world. In this study, we screened 324 swab and tissue samples from Polish pigeons and recovered 30 complete genomes, 16 of which came from birds displaying no obvious pathology. Together with 17 other publicly available PiCV complete genomes sampled throughout the Northern Hemisphere and Australia, we find that PiCV displays a similar degree of genetic diversity to that of the related psittacine-infecting circovirus species, beak and feather disease virus (BFDV). We show that, as is the case with its pathology and epidemiology, PiCV also displays patterns of recombination, genomic secondary structure and natural selection that are generally very similar to those of BFDV. It is likely that breeding facilities play a significant role in the emergence of new recombinant PiCV variants and given that ~50 % of the domestic pigeon population is infected subclinically, all pigeon breeding stocks should be screened routinely for this virus.

The prevalence and genetic characterization of Chlamydia psittaci from domestic and feral pigeons in Poland and the correlation between infection rate and incidence of pigeon circovirus

Chlamydiosis is a zoonotic disease caused by Chlamydia psittaci that occurs in a wide range of bird species. High infection rates with C. psittaci are found in pigeons, which can act as vectors transmitting this bacterium to poultry and humans. Chlamydia shedding by pigeons is intermittent and can be activated by stressors or immunosuppression. The most common immunosuppressive factor for pigeons is a pigeon circovirus (PiCV) infection. The main aim of the study was to evaluate the prevalence of C. psittaci in Polish populations of domestic and feral pigeons (Columba livia) in the context of its correlation with PiCV infections. The second objective was to determine the genetic characteristics of Polish C. psittaci isolates. The study was conducted on 377 pigeon samples (276 domestic and 101 feral pigeons) collected from pigeons from different regions of Poland. The average prevalence of C. psittaci in the Polish pigeon population was determined at 6.8%, and it was higher in domestic than in feral pigeons. This is the first ever study to suggest a potential correlation between C. psittaci and PiCV infections, which could be attributed to the fact that there are 2 to 3 times more pigeons infected with C. psittaci and coinfected with PiCV than pigeons infected with C. psittaci alone. This trend was observed mainly in the population of sick pigeons. As many as 88.2% of isolates were recognized as belonging to genotype B, and the remaining isolates were identified as belonging to genotype E. The isolates analyzed in this study demonstrated low levels of genetic variation (96-100% homology among the isolates and in relation to reference strains). Chlamydia psittaci could be expected to spread across pigeon populations due to the high probability of mutual infections between birds and the increasing number of PiCV infections.

Occurrence and genetic diversity of pigeon circovirus strains in Poland.

Pigeon circovirus (PiCV) is an immunosuppressive agent widespread throughout the world, which causes a disease in pigeons called Young Pigeon Disease Syndrome. The aim of the study was to evaluate the prevalence of PiCV in Poland and investigate the genetic diversity relative to other known PiCV isolates. Samples from 152 pigeon flocks (88 flocks of racing pigeons and 64 flocks of fancy pigeons) from various regions of Poland were tested by polymerase chain reaction and an approximately 326-base fragment of the capsid protein gene (Cap gene) of the virus was amplified. The average viral prevalence was found to be 70.3% (76.13% in racing pigeons and 62.5% in fancy pigeons). Among the obtained positive samples, 21 were selected for sequencing and a phylogenetic analysis was performed. It was found that the majority of Polish PiCV isolates, to varying degrees, are related to isolates occurring in Europe. It was also observed that the Cap gene is variable and mutations often occur in it, which impacts the amino acid sequences in the capsid protein (nucleotide similarity averaged 86.57%, amino acid similarity averaged 89.02%).

Genome Sequence of a Diverse Goose Circovirus Recovered from Greylag Goose

ABSTRACT A diverse goose circovirus (GoCV) genome was recovered from a wild hunted greylag goose (Anser anser) in Poland. The genome shares 83% pairwise identity with other GoCV genomes recovered from various geese from China, Germany, and Taiwan.

The epidemiology, molecular characterization and clinical pathology of circovirus infections in pigeons – current knowledge

ABSTRACT The first cases of circovirus infections in pigeons were documented less than 25 years ago. Since then, circovirus infections have been reported on nearly all continents. The specificity of pigeon breeding defies biosecurity principles, which could be the reason for the high prevalence of PiCV infections. PiCV infections in pigeons lead to atrophy of immune system organs and lymphocyte apoptosis. Infected birds could be more susceptible to infections of the respiratory and digestive tract. PiCV has been associated with the young pigeon disease syndrome (YPDS). PiCVs are characterized by high levels of genetic diversity due to frequent point mutations, recombination processes in the PiCV genome and positive selection. Genetic recombinations and positive selection play the key role in the evolution of PiCV. A protocol for culturing PiCV under laboratory conditions has not yet been developed, and traditional vaccines against the infection are not available. Recombinant capsid proteins for detecting anti-PiCV antibodies have been obtained, and these antigens can be used in the production of diagnostic tests and subunit vaccines against PiCV infections. However, YPDS has complex etiology, and it remains unknown whether immunization against PiCV alone will contribute to effective control of YPDS.

Immunological aspects of the efficiency of protectotype vaccination strategy against chicken infectious bronchitis

BackgroundOne of the most commonly applied protectotype vaccination protocol against infectious bronchitis (IB) in broiler chickens in the EU is simultaneous or alternate use of Ma5 and 4/91 vaccine strains. After IB vaccination and infection, systemic and upper respiratory tract (URT), humoral and cell-mediated immunity (CMI), are stimulated. The level of this stimulation correlates with the level of protection against IB.ResultsWe’ve investigated the development of URT and systemic, cell-mediated and humoral immunity in commercial broiler chickens vaccinated with Ma5 and/or 4/91 strains at hatch day. We’ve demonstrated that the group vaccinated with Ma5 and 4/91 strain simultaneously developed the most desirable immunity which reflects the level of CD8+ T cells stimulation in spleen and Harderian gland, as well as the level of IgA and IgY in URT washings and serum and their cross-reactivity with 7 IBV strains.ConclusionsAlthough we did not demonstrate directly why Ma5 + 4/91 protocol is so efficient it seems that it combines the benefits of monovalent vaccination with either Ma5 or 4/91 and while Ma5 seems to stimulate CMI more efficiently, the 4/91 strain generates a wider spectrum of immune system cross-reactivity and higher URT IgA production.

Recombinant Goose Circoviruses Circulating in Domesticated and Wild Geese in Poland

Circoviruses are circular single-stranded DNA (ssDNA) viruses that infect a variety of animals, both domestic and wild. Circovirus infection in birds is associated with immunosuppression and this in turn predisposes the infected animals to secondary infections that can lead to mortality. Farmed geese (Anser anser) in many parts of the world are infected with circoviruses. The majority of the current genomic information for goose circoviruses (GoCVs) (n = 40) are from birds sampled in China and Taiwan, and only two genome sequences are available from Europe (Germany and Poland). In this study, we sampled 23 wild and 19 domestic geese from the Gopło Lake area in Poland. We determined the genomes of GoCV from 21 geese; 14 domestic Greylag geese (Anser anser), three wild Greylag geese (A. anser), three bean geese (A. fabalis), and one white fronted goose (A. albifrons). These genomes share 83–95% nucleotide pairwise identities with previously identified GoCV genomes, most are recombinants with exchanged fragment sizes up to 50% of the genome. Higher diversity levels can be seen within the genomes from domestic geese compared with those from wild geese. In the GoCV capsid protein (cp) and replication associated protein (rep) gene sequences we found that episodic positive selection appears to largely mirror those of beak and feather disease virus and pigeon circovirus. Analysis of the secondary structure of the ssDNA genome revealed a conserved stem-loop structure with the G-C rich stem having a high degree of negative selection on these nucleotides.

An evaluation of the impact of aloe vera and licorice extracts on the course of experimental pigeon paramyxovirus type 1 infection in pigeons

Abstract The progressive decrease in the efficiency of synthetic drugs has prompted research into phytogenic feed additives with potentially immunomodulatory and anti‐infective properties. Complex diseases with a mixed etiology, including viral, pose a growing problem in domestic pigeons. The aim of this study was to determine the effectiveness of various doses of aloe vera and licorice extracts on the course of experimental PPMV‐1 infection in pigeons. The experiment was performed on pigeons divided into 5 groups, including one control group and 4 experimental groups, which were orally administered aloe vera or licorice extracts at 300 or 500 mg/kg BW for 7 d after experimental inoculation with PPMV‐1. On d 4, 7, and 14 after inoculation, cloacal swabs and samples of organs were collected from 4 birds in each group. The samples were analyzed to determine the copy number of PPMV‐1 RNA by TaqMan qPCR. The results indicate that licorice and aloe vera extracts inhibited PPMV‐1 replication by decreasing viral RNA copy numbers in the examined organs. The most inhibitory effect was observed in pigeons receiving aloe vera extract at 300 mg/kg BW, for which PPMV‐1 RNA copy numbers were approximately 7‐fold lower (brain), 9‐fold lower (kidneys), and 14‐fold lower (liver) than in the control group. The results of this study point to the potentially antiviral effects of aloe vera and licorice extracts in pigeons infected with PPMV‐1. To the best of our knowledge, this is the first study to investigate the antiviral properties of aloe vera and licorice extracts in domestic pigeons.

Application of pigeon circovirus recombinant capsid protein for detecting anti-PiCV antibodies in the sera of asymptomatic domestic pigeons and the potential use of a combination of serological and molecular tests for controlling circovirus infections in pigeon breeding flocks

&NA; The aim of this study was to evaluate the serologic status of domestic pigeons not infected and asymptomatically infected with the pigeon circovirus (PiCV) with the use of an enzyme‐linked assay based on PiCV recombinant capsid protein as a plate antigen. Recombinant PiCV capsid protein was produced by transforming E. coli BL21 (DE3) Rosetta colonies with expression plasmids. Blood samples and cloacal swabs were collected from 171 asymptomatic pigeons. The birds were divided into two groups (infected and not infected with PiCV) based on the results of Sybr Green real time PCR screening for the presence of PiCV genetic material. Approximately 70% of the pigeons tested positive for anti‐PiCV antibodies regardless of their infection status. Antibody levels, the coefficient of variation and standard deviation were significantly higher in the group of infected pigeons. The results indicate that ELISA is a highly useful test that complements molecular methods in evaluations of PiCV infection status in domestic pigeons. The spread of pigeon circovirus infections can be controlled by keeping breeding flocks free of PiCV, which can only be achieved by subjecting birds to real time PCR and serological tests.

Detection of Bordetella avium by TaqMan real-time PCR in tracheal swabs from wildlife birds

Bordetella avium, the causing agent of bordetellosis, a highly contagious infection of the respiratory tract in young poultry, causes significant losses in poultry farming throughout the world. Wildlife birds can be a reservoir of various pathogens that infect farm animals. For this reason the studies were conducted to estimate the prevalence of Bordetella avium in wildlife birds in Poland. Tracheal swab samples were collected from 650 birds representing 27 species. The bacterial DNA was isolated directly from the swabs and screened for Bordetella avium by TaqMan real-time PCR. The assay specificity was evaluated by testing DNA isolated from 8 other bacteria that can be present in avian respiratory tract, and there was no amplification from non-Bordetella avium agents. Test sensitivity was determined by preparing standard tenfold serial dilutions of DNA isolated from positive control. The assay revealed to be sensitive, with detection limit of approximately 4.07x10^2 copies of Bordetella avium DNA. The genetic material of Bordetella avium was found in 54.54% of common pheasants, in 9.09% of Eurasian coots, in 3.22% of black-headed gulls and in 2.77% of mallard ducks. The results of this study point to low prevalence of Bordetella avium infections in wildlife birds. The results also show that described molecular assay proved to be suitable for the rapid diagnosis of bordetellosis in the routine diagnostic laboratory.