Viral vector vaccines expressing nucleoprotein and phosphoprotein genes of avian bornaviruses ameliorate homologous challenge infections in cockatiels and common canaries.

Avian bornaviruses are causative agents of proventricular dilatation disease (PDD), an often fatal disease of parrots and related species (order Psittaciformes) which is widely distributed in captive psittacine populations and may affect endangered species. Here, we established a vaccination strategy employing two different well described viral vectors, namely recombinant Newcastle disease virus (NDV) and modified vaccinia virus Ankara (MVA) that were engineered to express the phosphoprotein and nucleoprotein genes of two avian bornaviruses, parrot bornavirus 4 (PaBV-4) and canary bornavirus 2 (CnBV-2). When combined in a heterologous prime/boost vaccination regime, NDV and MVA vaccine viruses established self-limiting infections and induced a bornavirus-specific humoral immune response in cockatiels (Nymphicus hollandicus) and common canaries (Serinus canaria forma domestica). After challenge infection with a homologous bornavirus, shedding of bornavirus RNA and viral loads in tissue samples were significantly reduced in immunized birds, indicating that vaccination markedly delayed the course of infection. However, cockatiels still developed signs of PDD if the vaccine failed to prevent viral persistence. Our work demonstrates that avian bornavirus infections can be repressed by vaccine-induced immunity. It represents a first crucial step towards a protective vaccination strategy to combat PDD in psittacine birds.

Avian bornavirus in free-ranging waterfowl: prevalence of antibodies and cloacal shedding of viral RNA.

We surveyed free-ranging Canada Geese (Branta canadensis), Trumpeter Swans (Cygnus buccinator), Mute Swans (Cygnus olor), and Mallards (Anas platyrhynchos) to estimate the prevalence of antibodies to avian bornavirus (ABV) and of cloacal shedding of ABV RNA in southern Ontario, Canada. Blood samples and cloacal swabs were collected from 206 free-ranging Canada Geese, 135 Trumpeter Swans, 75 Mute Swans, and 208 Mallards at 10 main capture sites between October 2010 and May 2012. Sera were assessed for antibodies against ABV by enzyme-linked immunosorbent assay and swabs were evaluated for ABV RNA using real-time reverse-transcription PCR. Serum antibodies were detected in birds from all four species and at each sampling site. Thirteen percent of the geese caught on the Toronto Zoo site shed ABV RNA in feces compared with 0% in geese sampled at three other locations. The proportions of shedders among Mute Swans, Trumpeter Swans, and Mallards were 9%, 0%, and 0%, respectively. Birds that were shedding viral RNA were more likely to have antibodies against ABV and to have higher antibody levels than those that were not, although many birds with antibodies were not shedding. We confirmed that exposure to, or infection with, ABV is widespread in asymptomatic free-ranging waterfowl in Canada; however, the correlation between cloacal shedding, presence of antibodies, and presence of disease is not fully understood.

[Genome virology: the novel interaction of RNA viruses and host genomes].

The origin of virus-like organisms probably dates back to the earliest forms of cellular life. Such a long coexistence between viruses and ourselves suggests that viruses may have crucially influenced the evolution of our species and vice versa. Sequences derived from retroviruses and retrotransposons have been shown to make up a substantial part of the human genome, suggesting a direct role of virus infection as a source of new genetic information and genomic innovation of the host species. Until very recently, retroviruses were the only viruses known to generate such endogenous copies in vertebrate genomes. However, we and others have reported recently that non-retroviral RNA viruses, including bornaviruses and filoviruses, have been endogenized repeatedly during mammalian evolution. These endogenous elements of RNA viruses not only provide evidence of ancient viral infections in each animal species but also offer novel paradigms for the interaction between RNA viruses and their hosts. Based on the presentation of the plenary lecture at the XV International Congress of Virology 2011, I will review here our recent findings regarding the generation and functions of endogenous bornavirus-like N elements in mammalian genomes, in order to reveal the unknown dynamics of RNA viruses in eukaryotic cells, and also discuss the evolutionary interaction between RNA viruses and hosts.

Pathogenesis of avian bornavirus in experimentally infected cockatiels.

Avian bornavirus (ABV) is the presumed causative agent of proventricular dilatation disease (PDD), a major fatal disease in psittacines. However, the influencing factors and pathogenesis of PDD are not known and natural ABV infection exhibits remarkable variability. We investigated the course of infection in 18 cockatiels that were intracerebrally and intravenously inoculated with ABV. A persistent ABV infection developed in all 18 cockatiels, but, as in natural infection, clinical disease patterns varied. Over 33 weeks, we simultaneously studied seroconversion, presence of viral RNA and antigens, infectious virus, histopathologic alterations, and clinical signs of infection in the ABV-infected birds. Our study results further confirm the etiologic role of ABV in the development of PDD, and they provide basis for further investigations of the pathogenetic mechanisms and disease-inducing factors for the development of PDD.

Diagnosis of Avian bornavirus infection in psittaciformes by serum antibody detection and reverse transcription polymerase chain reaction assay using feather calami.

Avian bornavirus (ABV) is the causative agent of proventricular dilatation disease (PDD), a highly devastating and contagious disease of psittacines (parrots and parakeets), which has resulted in the death of many captive birds. Accurate diagnosis of bornavirus infection is therefore important for the identification and isolation of infected birds. The current study showed that nonvascular contour (chest) feather calami provide a ready and minimally invasive source of RNA for the detection of ABV by reverse transcription polymerase chain reaction (RT-PCR). Storage of the feathers at room temperature for at least a month did not affect the results. Serological analysis by enzyme-linked immunosorbent assay (ELISA) showed that identification of anti-bornaviral nucleoprotein P40 antibodies can identify many birds with a past or present infection. The presence of anti-avian bornaviral P24 phosphoprotein and P16 matrix protein antibodies was quite variable, rendering these antibodies less useful for diagnosis of ABV infection. The significance of the present findings is that the use of nonvascular feathers as a source of RNA allows sample collection under conditions where storage of other samples would be difficult. Serum detection by ELISA of anti-P40 antibodies allows the identification of infected birds when RT-PCR fails.

Interplay between innate immunity and negative-strand RNA viruses: towards a rational model.

The discovery of a new class of cytosolic receptors recognizing viral RNA, called the RIG-like receptors (RLRs), has revolutionized our understanding of the interplay between viruses and host cells. A tremendous amount of work has been accumulating to decipher the RNA moieties required for an RLR agonist, the signal transduction pathway leading to activation of the innate immunity orchestrated by type I interferon (IFN), the cellular and viral regulators of this pathway, and the viral inhibitors of the innate immune response. Previous reviews have focused on the RLR signaling pathway and on the negative regulation of the interferon response by viral proteins. The focus of this review is to put this knowledge in the context of the virus replication cycle within a cell. Likewise, there has been an expansion of knowledge about the role of innate immunity in the pathophysiology of viral infection. As a consequence, some discrepancies have arisen between the current models of cell-intrinsic innate immunity and current knowledge of virus biology. This holds particularly true for the nonsegmented negative-strand viruses (Mononegavirales), which paradoxically have been largely used to build presently available models. The aim of this review is to bridge the gap between the virology and innate immunity to favor the rational building of a relevant model(s) describing the interplay between Mononegavirales and the innate immune system.

Presence of avian bornavirus RNA and anti-avian bornavirus antibodies in apparently healthy macaws.

Recently a novel avian bornavirus has been described that has been suggested to be the possible etiological agent for proventricular dilatation disease or macaw wasting disease. This article describes two macaws that shed avian bornaviral RNA sequences and demonstrated anti-avian bornavirus antibodies as revealed by reverse transcriptase polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and Western blot, yet are free of outward clinical signs of the disease.

Microbiology and immunology of autism spectrum disorders.

Both generic and environmental factors are likely to contribute to the pathogenesis of neurodevelopmental disorders. Even in heritable disorders of high penetrance, variability in timing of onset or severity of disease indicate a role for modifying principles. Investigation in animal models of the consequences of interactions between host response genes and microbes, toxins, and other environmental agents in a temporal context may elucidate the pathophysiology of a wide spectrum of chronic diseases. Here we review the evidence that infectious and immune factors may contribute to the pathogenesis of neurodevelopmental disorders, describe an animal model of neurodevelopmental disorders based upon viral infection, identify processes by which neural circuitry may be compromised, and outline plans for translational research in animal models and prospective human birth cohorts.