Ability to detect antibodies to beak and feather disease virus in blood on filter paper decreases with duration of storage

Background Beak and feather disease virus (BFDV) is a circovirus that infects captive and wild psittacine birds, and is of conservation concern. The haemagglutination inhibition (HI) assay is used to determine antibody titres against BFDV, and the use of dried blood spots (DBS) on filter paper stored at room temperature has been suggested to be an equally valid technique to the use of frozen serum. However, research on other pathogens has found variable results when investigating the longevity of antibodies stored on DBS at room temperature. Consequently, we aimed to test the temporal stability of antibodies to BFDV in DBS samples stored long-term at room temperature. A further goal was to add to the current knowledge of antibody response to naturally acquired BFDV infection in crimson rosellas (Platycercus elegans). Methods Blood was collected from wild P. elegans in Victoria, Australia, that had been live-trapped (n = 9) or necropsied (n = 11). BFDV virus load data were obtained from blood stored in ethanol by real-time quantitative PCR (qPCR); antibody titres were obtained by HI assay from either DBS or serum samples, which had been collected concurrently. All HI assays were performed commercially by the Veterinary Diagnostic Laboratory (VDL) in Charles Sturt University, Australia, who were blind to BFDV blood status. Results HI titres from DBS stored at room temperature declined significantly over time (~80 weeks). By contrast, frozen serum samples assayed after 80 weeks in storage all had high HI titres, only varying up to one dilution step from the initial HI titres obtained from DBS at 3–6 weeks after sampling. Weak HI titres from DBS samples all came back negative when the test was repeated only nine weeks later. Novel high HI titres were reported in P. elegans, and while most birds with high antibody titres had corresponding negative qPCR results, a single subadult presented with high HI titres and virus load simultaneously. Conclusion Detection of antibodies on filter paper stored at room temperature decreases over time, increasing the chances of false negatives in these samples, and in repeated testing of samples with weak HI titres. Consequently, serum should be the preferred sample type to use for seroepidemiological studies on BFDV in parrots and other bird species. When not possible, it may help to store DBS on filter paper at −20 °C or lower. However, prompt testing of DBS samples (e.g., <6 weeks in storage) is recommended pending further research on antibody temporal stability. We also show that P. elegans, especially adults, can produce high antibody titres against BFDV, which may help them resist infection.

Evolution of Beak and Feather Disease Virus across Three Decades of Conservation Intervention for Population Recovery of the Mauritius Parakeet

Emerging infectious diseases (EIDs) are key contributors to the current global biodiversity crisis. Psittaciformes (parrots) are one of the most vulnerable avian taxa and psittacine beak and feather disease (PBFD) is the most common viral disease in wild parrots. PBFD is caused by the beak and feather disease virus (BFDV), which belongs to the Circoviridae family and comprises a circular, single-stranded DNA genome. BFDV is considered to have spread rapidly across the world and, in 2005, an outbreak of PBFD was documented in the recovering population of the Mauritius parakeet (Alexandrinus eques). The Mauritius parakeet was once the world’s rarest parrot and has been successfully recovered through 30 years of intensive conservation management. Molecular surveillance for the prevalence of BFDV was carried out across a 24-year sample archive spanning the period from 1993 to 2017, and DNA sequencing of positive individuals provided an opportunity to assess patterns of phylogenetic and haplotype diversity. Phylogenetic analyses show variation in the extent of viral diversification within the replicase protein (Rep). Timeseries of BFDV prevalence and number of haplotypes reveal that two subsequent waves of infection occurred in 2010/2011 and 2013/2014 following the initial outbreak in 2005. Continued disease surveillance to determine the frequency and intensity of subsequent waves of infection may benefit future translocation/reintroduction planning. The continued growth of the Mauritius parakeet population despite the presence of BFDV bodes well for its long-term persistence.

Viromic Analysis of Feces From Laboratory Rabbits Reveals a Novel Circovirus

Circoviruses are responsible for fatal diseases that can affect mammals and birds. Beak and feather disease virus (BFDV) is responsible for fatal diseases of birds, causing the psittacine beak and feather disease. The current study discovered a novel circovirus named RabCV from feces of laboratory rabbits, which shows close relationship to BFDVs. This novel circovirus was discovered from feces of rabbits, which showed low prevalence in the healthy laboratory rabbits. BFDV is responsible for fatal diseases that could affect birds, which suggested that the potential threat of the novel rabbit circovirus to the health of laboratory rabbits needs further study.

Molecular Survey of Pathogens in Wild Amazon Parrot Nestlings: Implications for Conservation

South America presents the greatest Psittacidae diversity in the world, but also has the highest numbers of threatened parrot species. Recently, exotic viruses have been detected in captive native psittacine birds in Brazil, however, their impacts on the health of wild parrots are still unknown. We evaluated the presence of Chlamydia psittaci, Psittacid alphaherpesvirus 1 (PsHV-1), avipoxvirus and beak and feather disease virus (BFDV) in wild Amazona aestiva, A.brasiliensis and A.pretrei nestlings and in wild caught A.aestiva nestlings seized from illegal trade. Samples were collected from 205 wild nestlings and 90 nestlings from illegal trade and pathogen-specific PCR was performed for each sample. Chlamydia DNA prevalence was 4.7% in A.aestiva and 2.5% in A.brasiliensis sampled from the wild. Sequencing revealed that the C.psittaci sample belonged to the genotype A. PsHV-1, avipoxvirus and BFDV DNA was not detected. These results have conservation implications since they suggest that wild parrot populations have a low prevalence of the selected pathogens and, apparently, they were not reached by the exotic BFDV. Stricter health protocols should be established as condition to reintroduction of birds to the wild to guarantee the protection of Neotropical parrots.

Genetic signatures of population bottlenecks, relatedness, and inbreeding highlight recent and novel conservation concerns in the Egyptian vulture

The assessment of temporal variation in genetic features can be particularly informative on the factors behind demography and viability of wildlife populations and species. We used molecular methods to evaluate neutral genetic variation, relatedness, bottlenecks, and inbreeding in a declining population of Egyptian vulture (Neophron percnopterus) in central Spain. The results show that the genetic diversity remained relatively stable over a period of twelve years despite the decline in census and effective population sizes in the last decades. A relatively high proportion of nestlings from different and distant territories showed high relatedness in each study year. We also found support for an increasing impact of severe recent (contemporary) rather than distant (historical) past demographic bottlenecks, and the first evidence of inbred mating between full siblings coinciding with lethal malformations in offspring. The inbred nestling with feather malformations was positive to beak and feather disease virus recorded for the first time in this species. These results alert on recent and novel threats potentially affecting health and reducing the adaptive potential of individuals in this threatened species.

Psittacine beak and feather disease virus and avian polyomavirus detection rate in clinically healthy captive birds in the Czech Republic

The aim of this study was to document the detection rate of the beak and feather disease virus (BFDV) and avian polyomavirus (APV) across clinically healthy captive parrots in the Czech Republic. The presence of the BFDV and APV was tested using a nested polymerase chain rection (PCR) in 177 parrots originating from 34 facilities (breeding facilities, private owners). Positive BFDV results came from 38 parrots (21.5%) within 12 facilities (35.3%). Two parrots (1.1%) originating from two different facilities (5.9%) tested positive for APV. The results show a high detection rate of BFDV in the clinically healthy captive parrot populations in the Czech Republic. Preventive measures to stop the spread of this virus are, thus, essential.