RESUMEN
BACKGROUND: Porcine circovirus 2 is the primary agent responsible for inducing a group of associated diseases known as Porcine Circovirus Associated Diseases (PCVAD), which can have detrimental effects on production efficiency as well as causing significant mortality. The objective of this study was to evaluate variation in viral replication, immune response and growth across pigs (n = 974) from different crossbred lines. The approach used in this study was experimental infection with a PCV2b strain of pigs at an average of 43 days of age. RESULTS: The sequence of the PCV2b isolate used in the challenge was similar with a cluster of PCV2b isolates known to induce PCVAD and increased mortality rates. The swine leukocyte antigen class II (SLAII) profile of the population was diverse, with nine DQB1 haplotypes being present. Individual viremia and antibody profiles during challenge demonstrate variation in magnitude and time of viral surge and immune response. The correlations between PCV2 specific antibodies and average daily gain (ADG) were relatively low and varied between - 0.14 to 0.08 for IgM and -0.02 and 0.11 for IgG. In contrast, PCV2 viremia was an important driver of ADG decline following infection; a moderate negative correlation was observed between viral load and overall ADG (r = - 0.35, P < 0.001). The pigs with the lowest 10% level of viral load maintained a steady increase in weekly ADG (P < 0.0001) compared to the pigs that had the 10% greatest viral load (P < 0.55). In addition, the highly viremic group expressed higher IgM and IgG starting with d 14 and d 21 respectively, and higher tumor necrosis factor - alpha (TNF-α) at d 21 (P < 0.005), compared to low viremic group. CONCLUSIONS: Molecular sources of the observed differences in viremia and immune response could provide a better understanding of the host factors that influence the development of PCVAD and lead to improved knowledge of swine immunity.
Asunto(s)
Infecciones por Circoviridae/veterinaria , Circovirus/inmunología , Enfermedades de los Porcinos/virología , Viremia/veterinaria , Animales , Infecciones por Circoviridae/inmunología , Infecciones por Circoviridae/virología , Circovirus/patogenicidad , Susceptibilidad a Enfermedades/inmunología , Susceptibilidad a Enfermedades/veterinaria , Susceptibilidad a Enfermedades/virología , Inmunidad/inmunología , Porcinos/crecimiento & desarrollo , Porcinos/virología , Enfermedades de los Porcinos/inmunología , Factores de Tiempo , Carga Viral/veterinaria , Viremia/inmunología , Viremia/virología , Replicación ViralRESUMEN
Chronic wasting disease (CWD), a transmissible spongiform encephalopathy of deer, elk, and moose, is the only prion disease affecting free-ranging animals. Since the disease was first identified in northern Colorado and southern Wyoming in 1967, new epidemic foci of the disease have been identified in 20 additional states, as well as two Canadian provinces and the Republic of South Korea. Identification of CWD-affected animals currently requires postmortem analysis of brain or lymphoid tissues using immunohistochemistry (IHC) or an enzyme-linked immunosorbent assay (ELISA), with no practical way to evaluate potential strain types or to investigate the epidemiology of existing or novel foci of disease. Using a standardized real-time (RT)-quaking-induced conversion (QuIC) assay, a seeded amplification assay employing recombinant prion protein as a conversion substrate and thioflavin T (ThT) as an amyloid-binding fluorophore, we analyzed, in a blinded manner, 1,243 retropharyngeal lymph node samples from white-tailed deer, mule deer, and moose, collected in the field from areas with current or historic CWD endemicity. RT-QuIC results were then compared with those obtained by conventional IHC and ELISA, and amplification metrics using ThT and thioflavin S were examined in relation to the clinical history of the sampled deer. The results indicate that RT-QuIC is useful for both identifying CWD-infected animals and facilitating epidemiological studies in areas in which CWD is endemic or not endemic.
Asunto(s)
Técnicas de Laboratorio Clínico/métodos , Ganglios Linfáticos/patología , Rumiantes , Enfermedad Debilitante Crónica/diagnóstico , Amiloide/análisis , Animales , Femenino , Fluorescencia , Masculino , Coloración y Etiquetado/métodos , Factores de TiempoRESUMEN
The precision of a Porcine reproductive and respiratory syndrome virus (PRRSV) oral fluid antibody enzyme-linked immunosorbent assay (ELISA) was evaluated by calculating reliability coefficients for assay repeatability (within laboratory) and assay reproducibility (between laboratories). Randomly ordered oral fluid samples of known (n = 39) and unknown (n = 224) PRRSV antibody status were tested in 12 diagnostic laboratories. Each laboratory tested the samples twice, first using an antibody ELISA kit and reagents provided to them (phase 1) and then using an ELISA kit and reagents configured in their respective laboratory (phase 2). Repeatability (within laboratory) reliability coefficients calculated using results from samples of known PRRSV antibody status ranged from 0.724 to 0.997 in phase 1 and from 0.953 to 0.998 in phase 2. Reproducibility (between laboratories) reliability coefficients were calculated for 3 conditions: case 1--samples of unknown status (n = 224); case 2--samples of known status (n = 39), and case 3--all samples (n = 263). Among the 3 cases, reliability coefficients ranged from 0.937 to 0.964 in phase 1 and from 0.922 to 0.935 in phase 2. For case 3, it was estimated that 96.67% of the total variation in phase 1 and 93.21% in phase 2 could be attributed to the oral fluid samples themselves. Overall, the PRRSV oral fluid antibody ELISA was highly repeatable and reproducible. The current study supports the routine use of this test in laboratories providing diagnostic service to pig producers.
Asunto(s)
Anticuerpos Antivirales/análisis , Ensayo de Inmunoadsorción Enzimática/veterinaria , Síndrome Respiratorio y de la Reproducción Porcina/diagnóstico , Virus del Síndrome Respiratorio y Reproductivo Porcino/inmunología , Saliva/inmunología , Animales , Ensayo de Inmunoadsorción Enzimática/métodos , Síndrome Respiratorio y de la Reproducción Porcina/inmunología , Síndrome Respiratorio y de la Reproducción Porcina/virología , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , PorcinosRESUMEN
Respiratory swab samples were collected from 5 pet ferrets (Mustela putorius furo) exhibiting influenza-like illness. The ferrets represented 3 households in 2 states. In each case, the owners reported influenza-like illness in themselves or family members prior to the onset of a similar illness in the ferrets. Real-time reverse transcription polymerase chain reaction assays designed for the detection of the 2009 H1N1 Influenza A virus were conducted in the state animal health laboratories. The assays included detection of the matrix gene of Influenza A virus and neuraminidase gene specific for 2009 H1N1 virus. Samples were positive for both screening assays. The samples were confirmed positive by the National Veterinary Services Laboratories. The history of illness in family members prior to illness in the ferrets suggests that Influenza A virus was transmitted from humans to the ferrets.
Asunto(s)
Gripe Humana/transmisión , Infecciones por Orthomyxoviridae/diagnóstico , Animales , Animales Domésticos/virología , Transmisión de Enfermedad Infecciosa/veterinaria , Hurones , Hemaglutininas Virales/genética , Humanos , Subtipo H1N1 del Virus de la Influenza A/enzimología , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Neuraminidasa/genética , Oregon , Infecciones por Orthomyxoviridae/epidemiología , Infecciones por Orthomyxoviridae/transmisión , Filogenia , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Seven juveniles and 3 adults from a closed group of 19 rock hyraxes (Procavia capensis) housed in a zoo's indoor rock exhibit died or were euthanized after developing blepharoconjunctivitis and orofacial ulcers over a 2-week period. Histopathologic examination of dermal ulcers and ulcerated tongues revealed amphophilic to basophilic intranuclear inclusion bodies in epithelial cells bordering ulcers. Epithelial cells with inclusion bodies were often characterized by cytomegaly and karyomegaly, and many cells had formed syncytia. Examination of inclusion bodies in tongue epithelium by transmission electron microscopy revealed icosahedral nucleocapsids, approximately 80-95 nm in diameter, with morphologic features consistent with herpesvirus. Cytopathic effect (CPE) typical of alphaherpesvirus infection was seen in bovine turbinate, equine dermal, and Vero cell monolayers after inoculation with homogenates of the skin lesions, but CPE was not seen after inoculation onto Madin-Darby canine kidney or swine testicle cell monolayers. Polymerase chain reaction analysis using degenerate primers that targeted a portion of the herpesvirus polymerase gene generated a product of approximately 227 base pairs. The product was cloned, sequenced, and then analyzed using BLAST. At the nucleotide level, there was 86%, 77%, and 76% shared identity with Eidolon herpesvirus 1, Human herpesviruses 1 and 2, and Cercopithecine herpesvirus 2, respectively. Herpesvirus infections in rock hyraxes have not been characterized. The data presented in the current study suggest that a novel alphaherpesvirus caused the lesions seen in these rock hyraxes. The molecular characteristics of this virus would tentatively support its inclusion in the genus Simplexvirus.
Asunto(s)
Infecciones por Herpesviridae/veterinaria , Herpesviridae/aislamiento & purificación , Damanes , Animales , Conjuntivitis Viral/patología , Conjuntivitis Viral/veterinaria , Conjuntivitis Viral/virología , Herpesviridae/clasificación , Herpesviridae/genética , Infecciones por Herpesviridae/patología , Infecciones por Herpesviridae/virología , Filogenia , Enfermedades Cutáneas Virales/patología , Enfermedades Cutáneas Virales/veterinaria , Enfermedades Cutáneas Virales/virologíaRESUMEN
The nucleotide sequence of a highly pathogenic porcine reproductive and respiratory syndrome virus (PRRSV) was determined. Transfection of MARC-145 cells with capped in vitro transcripts derived from a full-length cDNA clone of the viral genome resulted in infectious PRRSV with growth characteristics similar to that of the parental virus. Primer extension analysis revealed that during replication, the viral polymerase corrected the two nonviral guanosine residues present at the 5' terminus of the transfected transcripts. Animal studies showed that the cloned virus induced hyperthermia, persistent viremia, and antibody response, similar to that observed with the parental virus. Contact transmission occurred rapidly within 3 days of introduction of naïve pigs into the group of clone virus-inoculated pigs. These results suggest that the cloned virus retains the in vivo virulence and contagion properties of the parental virus, thus, providing the background for reverse genetics manipulation in systematic examination of attenuation and virulence phenotypes.
Asunto(s)
ADN Viral/genética , Virus del Síndrome Respiratorio y Reproductivo Porcino/genética , Virus del Síndrome Respiratorio y Reproductivo Porcino/patogenicidad , Animales , Secuencia de Bases , Clonación Molecular , Cartilla de ADN/genética , ADN Complementario/genética , Genoma Viral , Síndrome Respiratorio y de la Reproducción Porcina/transmisión , Síndrome Respiratorio y de la Reproducción Porcina/virología , Virus del Síndrome Respiratorio y Reproductivo Porcino/fisiología , Sus scrofa , Virulencia/genética , Replicación ViralRESUMEN
Understanding the dynamics of porcine reproductive and respiratory syndrome virus (PRRSV) persistence in individual pigs is essential to the development of successful control programs. The objectives of this study were to investigate the proportion of inoculated pigs that become persistently infected with PRRSV and the duration of their infection. Additionally, different diagnostic techniques that detect persistent infections were compared. Twenty-eight 35-day-old pigs were inoculated with PRRSV. Serum and tonsil biopsy samples were collected on days 0, 7, 14, and 28 and then approximately monthly thereafter until day 251 postinoculation (p.i.). Tonsil, lymph node, and lung samples were collected following euthanasia on day 251 p.i. Virus was isolated from serum and tonsil biopsy samples that had been collected through days 28 and 56 p.i., respectively. Viral RNA was detected by reverse transcription (RT)-PCR in serum and tonsil biopsy samples that had been collected through day 251 p.i., although no serum samples collected from days 84 to 196 p.i. were positive and the presence of infectious PRRSV was not detected by swine bioassay of tissue samples collected at necropsy. The results confirmed that RT-PCR is more sensitive than virus isolation in identifying PRRSV-infected pigs. Six pigs that were persistently infected through days 225 or 251 p.i. remained seropositive throughout the study, although one pig had an enzyme-linked immunosorbent assay sample-to-positive ratio that was only slightly above the cutoff value of 0.40. Twenty of 28 tonsil biopsy samples collected on day 84 p.i. were positive by RT-PCR compared to only 1 positive biopsy sample out of 28 collected on day 119 p.i. The study's results indicate that most pigs clear PRRSV within 3 to 4 months, but that some may remain persistently infected for several months.