Helton Fernandes dos Santos

Discovery of a genome of a distant relative of chicken anemia virus reveals a new member of the genus Gyrovirus

A 2.4-kb phi29 polymerase amplification product from serum of a diseased chicken was cloned and sequenced. The 2383-nucleotide sequence showed about 40% identity to a representative genome of chicken anemia virus (CAV), the only member of the genus Gyrovirus, family Circoviridae. The new genome had an organization similar to that of CAV: a putative 5′ untranscribed region of about 400 nt followed by three partially overlapping open reading frames encoding VP1, VP2 and VP3 homologs. The amino acid identities between these homologs and those of CAV were 38.8%, 40.3%, and 32.2%, respectively. Based on these limited similarities, it is proposed that the newly identified virus is a member of a new species in the genus Gyrovirus. For this new species, the name Avian gyrovirus 2 (AGV2) is proposed.

Genomic characterization of novel circular ssDNA viruses from insectivorous bats in Southern Brazil.

Circoviruses are highly prevalent porcine and avian pathogens. In recent years, novel circular ssDNA genomes have recently been detected in a variety of fecal and environmental samples using deep sequencing approaches. In this study the identification of genomes of novel circoviruses and cycloviruses in feces of insectivorous bats is reported. Pan-reactive primers were used targeting the conserved rep region of circoviruses and cycloviruses to screen DNA bat fecal samples. Using this approach, partial rep sequences were detected which formed five phylogenetic groups distributed among the Circovirus and the recently proposed Cyclovirus genera of the Circoviridae. Further analysis using inverse PCR and Sanger sequencing led to the characterization of four new putative members of the family Circoviridae with genome size ranging from 1,608 to 1,790 nt, two inversely arranged ORFs, and canonical nonamer sequences atop a stem loop.

Variants of the recently discovered avian gyrovirus 2 are detected in Southern Brazil and The Netherlands

A genome of a virus preliminarily named avian gyrovirus 2 (AGV2), a close relative to chicken anemia virus, was recently discovered in a chicken in the state of Rio Grande do Sul, Southern Brazil. To study the occurrence of AGV2 in Rio Grande do Sul and the neighboring state Santa Catarina, a number of adult chickens (n=108 and n=48, respectively) were tested for the presence of AGV2 DNA. An AGV2-specific PCR was developed, optimized and used to analyze DNA extracted from clinical samples. AGV2 DNA was detected in 98/108 (90.7%) of samples collected in the state of Rio Grande do Sul and 29/48 (60.4%) of the samples collected in the state of Santa Catarina. In order to check whether AGV2 DNA would be detected in samples from a geographically distant region, DNA from brain samples of 21 diseased chickens from the Netherlands were tested independently, by the same method. In such specimens, 9/21 (42.9%) brain tissue samples were found to contain AVG2 DNA. Sequence analysis of some of the PCR products demonstrated that the amplified AGV2 sequences could vary up to 15.8% and could preliminarily be divided in three groups. This indicated the occurrence of variants of AGV2, which may reflect differences in geographical origin and/or in biological properties. The data presented here provides evidence that AGV2 seems fairly distributed in chickens in Southern Brazil and that AGV2 also circulates in the Netherlands. Besides, circulating viruses display genetic variants whose significance should be further examined, particularly to determine whether AGV2 would play any role in chicken diseases.

Efficacy of an inactivated, recombinant bovine herpesvirus type 5 (BoHV-5) vaccine

Bovine herpesvirus type 5 (BoHV-5) is the causative agent of bovine herpetic encephalitis. In countries where BoHV-5 is prevalent, attempts to vaccinate cattle to prevent clinical signs from BoHV-5-induced disease have relied essentially on vaccination with BoHV-1 vaccines. However, such practice has been shown not to confer full protection to BoHV-5 challenge. In the present study, an inactivated, oil adjuvanted vaccine prepared with a recombinant BoHV-5 from which the genes coding for glycoprotein I (gI), glycoprotein E (gE) and membrane protein US9 were deleted (BoHV-5 gI/gE/US9(-)), was evaluated in cattle in a vaccination/challenge experiment. The vaccine was prepared from a virus suspension containing a pre-inactivation antigenic mass equivalent to 10(7.69) TCID(50)/dose. Three mL of the inactivated vaccine were administered subcutaneously to eight calves serologically negative for BoHV-5 (vaccinated group). Four other calves were mock-vaccinated with an equivalent preparation without viral antigens (control group). Both groups were boostered 28 days later. Neither clinical signs of disease nor adverse effects were observed during or after vaccination. A specific serological response, revealed by the development of neutralizing antibodies, was detected in all vaccinated animals after the first dose of vaccine, whereas control animals remained seronegative. Calves were subsequently challenged on day 77 post-vaccination (pv) with 10(9.25) TCID(50) of the wild-type BoHV-5 (parental strain EVI 88/95). After challenge, vaccinated cattle displayed mild signs of respiratory disease, whereas the control group developed respiratory disease and severe encephalitis, which led to culling of 2/4 calves. Searches for viral DNA in the central nervous system (CNS) of vaccinated calves indicated that wild-type BoHV-5 did not replicate, whereas in CNS tissues of calves on the control group, viral DNA was widely distributed. BoHV-5 shedding in nasal secretions was significantly lower in vaccinated calves than in the control group on days 2, 3, 4 and 6 post-challenge (pc). In addition, the duration of virus shedding was significantly shorter in the vaccinated (7 days) than in controls (12 days). Attempts to reactivate latent infection by administration of dexamethasone at 147 days pv led to recrudescence of mild signs of respiratory disease in both vaccinated and control groups. Infectious virus shedding in nasal secretions was detected at reactivation and was significantly lower in vaccinated cattle than in controls on days 11-13 post-reactivation (pr). It is concluded that the inactivated vaccine prepared with the BoHV-5 gI/gE/US9(-) recombinant was capable of conferring protection to encephalitis when vaccinated cattle were challenged with a large infectious dose of the parental wild type BoHV-5. However, it did not avoid the establishment of latency nor impeded dexamethasone-induced reactivation of the virus, despite a significant reduction in virus shedding after challenge and at reactivation on vaccinated calves.

Quillaja brasiliensis saponins induce robust humoral and cellular responses in a bovine viral diarrhea virus vaccine in mice

A saponin fraction extracted from Quillaja brasiliensis leaves (QB-90) and a semi-purified aqueous extract (AE) were evaluated as adjuvants in a bovine viral diarrhea virus (BVDV) vaccine in mice. Animals were immunized on days 0 and 14 with antigen plus either QB-90 or AE or an oil-adjuvanted vaccine. Two-weeks after boosting, antibodies were measured by ELISA; cellular immunity was evaluated by DTH, lymphoproliferation, cytokine release and single cell IFN-γ production. Serum anti-BVDV IgG, IgG1 and IgG2b were significantly increased in QB-90- and AE-adjuvanted vaccines. A robust DTH response, increased splenocyte proliferation, Th1-type cytokines and enhanced production of IFN-γ by CD4(+) and CD8(+) T lymphocytes were detected in mice that received QB-90-adjuvanted vaccine. The AE-adjuvanted preparation stimulated humoral responses but not cellular immune responses. These findings reveal that QB-90 is capable of stimulating both cellular and humoral immune responses when used as adjuvant.

Faecal virome of healthy chickens reveals a large diversity of the eukaryote viral community, including novel circular ssDNA viruses

This study is focused on the identification of the faecal virome of healthy chickens raised in high-density, export-driven poultry farms in Brazil. Following high-throughput sequencing, a total of 7743 de novo-assembled contigs were constructed and compared with known nucleotide/amino acid sequences from the GenBank database. Analyses with blastx revealed that 279 contigs (4 %) were related to sequences of eukaryotic viruses. Viral genome sequences (total or partial) indicative of members of recognized viral families, including Adenoviridae, Caliciviridae, Circoviridae, Parvoviridae, Picobirnaviridae, Picornaviridae and Reoviridae, were identified, some of those representing novel genotypes. In addition, a range of circular replication-associated protein encoding DNA viruses were also identified. The characterization of the faecal virome of healthy chickens described here not only provides a description of the viruses encountered in such niche but should also represent a baseline for future studies comparing viral populations in healthy and diseased chicken flocks. Moreover, it may also be relevant for human health, since chickens represent a significant proportion of the animal protein consumed worldwide.

Torque teno sus virus 1 (TTSuV1) and 2 (TTSuV2) viral loads in serum of postweaning multisystemic wasting syndrome (PMWS)-affected and healthy pigs in Brazil.

Associations between Torque teno sus viruses (TTSuVs) and the occurrence of postweaning multisystemic wasting syndrome (PMWS) have been reported with controversial results. Currently, no studies have been performed comparing simultaneously viral loads of TTSuVs and PCV2. To examine the role for TTSuVs in PMWS-affected animals, a SYBR Green-based quantitative PCR (qPCR) was designed to detect and quantify TTSuV1, TTSuV2 and PCV2 genomes in swine sera. TTSuV1 genome loads were significantly higher in healthy adults than in young and SPF animals (p<0.05) suggesting that the prevalence of TTSuV1 infection increases with age and bears no association with PMWS. Regarding TTSuV2, no significant variation was detected in viral loads within any of the groups. As expected, PCV2 genome loads were higher in PMWS-affected swine than in healthy or SPF animals (p<0.001). These findings provide clear evidence to indicate that neither TTSuV1 nor TTSuV2 viral loads have any correlation with the occurrence of PMWS.

Genome sequence of bubaline alphaherpesvirus 1 (BuHV1) isolated in Australia in 1972

Bubaline alphaherpesvirus 1 (BuHV1) is a member of the family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus. To date, no full genome sequence of BuHV has been published. Here, we report the complete genome sequence of bubaline alphaherpesvirus 1 (BuHV1) strain b6 (BuHV1-b6), isolated from a water buffalo (Bubalus bubalis) in 1972 in Australia. The virus was multiplied in MDBK cells, and the DNA was extracted and subjected to high-throughput sequencing. The reads were aligned and combined into a single genome sequence, with bovine alphaherpesvirus 5 (BoHV5) strain SV507/99 (accession number NC005261) as a reference. The BuHV1-b6 genome is a linear double-stranded DNA molecule, 137,452 bp long, with a GC content of 76.8%. The genome consists of two unique sequences: a long, or UL, sequence (103,818 bp) and a short, or US, sequence (9,586 bp), with the latter being flanked by inverted IR and TR elements of 12,024 bp each. The arrangement is typical of herpesvirus genomes of the D-type. The overall sequence has a 92.2% similarity at the nucleotide level to the reference BoHV5 strain. Our report provides a significant landmark in the history of herpesviruses, represented by the genome sequence of this 44-year-old virus isolate.

Chicken parvovirus and its associations with malabsorption syndrome

Malabsorption syndrome (MAS) is a multifactorial syndrome which is characterized by enteric disorders and reduced growth rates of broilers. Such condition is responsible for significant economic losses to the poultry industry. A possible association between chicken parvovirus (ChPV) infections and the occurrence of MAS has been proposed. However, such association has not to date been elucidated in view that ChPV has been detected in healthy as well as in MAS-affected chickens. This study aimed to detect and quantify ChPV loads in sera and tissues of MAS-affected, as well as in healthy broilers. Fifty nine, 39-day-old broilers (50 diseased, 9 healthy birds), obtained from the same flocks, were examined. The highest ChPV DNA loads were detected in MAS-affected broilers, particularly in fecal samples and intestinal tissues (~5500 genomic copies/300ng of total DNA). The average viral genome load in serum in MAS-affected birds was 1134copies/mL, whereas no viral DNA was found in sera and thymus tissues from healthy animals. These findings reveal that MAS-affected broilers consistently carry ChPV DNA is serum, whereas healthy animals do not. In addition, viral loads in tissues (bursa of Fabricius, spleen, intestine and liver) of MAS-affected birds were significantly higher in comparison to the same tissues from healthy broilers. Although preliminary, the results obtained here indicate an association between the detection of ChPV DNA in serum, in addition to high ChPV viral loads in tissues, and the occurrence of MAS in broilers. Further experiments should be performed to confirm such results.

Newcastle disease vaccination in captive-bred wild birds

The breeding of wild birds in captivity assumes an increasingly important role in conservation due to the loss of species and their habitats. Providing the environmental and nutritional needs of species kept in captivity is the key for achieving success in such initiatives. Among the flock health practices, we highlight here wild bird vaccination, a scarcely studied subject. This study clinically and serologically evaluates the effect of applying a vaccination protocol against Newcastle disease in three groups of ornamental wild birds. The responses observed in 10 ornamental chickens were compared to those recorded in 12 ring-neck pheasants (Phasianus colchicus), 6 psittacines (2 cockatiels Nymphicus hollandicus, 2 lorikeets Trichoglossus haematodus molucanos, and 2 eastern rosellas Platycercus eximius), and 6 touracos (2 guinea Tauraco persa, 2 white-cheeked Tauraco leucotis, and 2 violet Musophaga violacea). One drop of each live Newcastle HB1 and La Sota vaccines were ocularly instilled on the 1st and 21st experimental days, respectively. On the 112th day, one shot of an inactivated oily Newcastle vaccine was intramuscularly injected. Serum samples were submitted to the Newcastle disease virus antibody Test Kit ELISA-BioChek. Except for the psittacines, other bird species showed a considerable increase in the antibody titers. However, their mean antibody titers differed significantly (P < 0.05) from that recorded in the chickens.