Altered indirect hemagglutination method for easy serotyping of Haemophilus parasuis / Método de Hemaglutinação Indireta alterado para facilitar a sorotipificação de Haemophilus parasuis

Glässer's disease is an emergent bacterial disease that affects swine husbandries worldwide causing important economic losses. The aetiological agent, Haemophilus parasuis, is currently divided in fifteen serovars but an increasing number of non-typeable serovars have been reported. Indirect hemagglutination (IHA) is indicated as a serotyping method for H. parasuis. In the present study, we describe an additional step that aims to work around a possible obstacle in the original protocol that may compromise the outcome of this assay. We observed that the choice of anticoagulant for blood collection influences and/or impairs spontaneous adsorption of H. parasuis antigens on sheep red blood cells (SRBCs). However, regardless of the anticoagulant used, chemical treatment of SRBCs with tannic acid induces a stable antigen adsorption (sensitization step). The addition of 1% BSA to SRBCs washing buffer and to antisera dilution augments IHA specificity. Tannic acid treated SRBCs combined with thermo-resistant H. parasuis antigens increases the assay resolution. Thus, our results demonstrate an improvement in the technique of H. parasuis serotyping that will prove valuable to understand Glässer's disease epidemiology and to better characterize serovars involved in outbreaks.(AU)

A Doença de Glässer é uma doença bacteriana emergente que afeta a produção de suínos em todo o mundo e causa importantes perdas econômicas. O agente etiológico, Haemophilus parasuis, é atualmente dividido em quinze sorovares; no entanto, um número crescente de cepas não tipificáveis tem sido relatado. O teste de hemaglutinação indireta (IHA) tem sido utilizado para a sorotipificação de H. parasuis. Neste estudo, descrevemos uma alteração no protocolo original de IHA e que supera uma limitação específica que pode comprometer o uso geral deste ensaio. Descobrimos que o tipo de anticoagulante utilizado para coletar os eritrócitos ovinos (SRBCs) pode comprometer a adsorção espontânea dos antígenos do H. parasuis. Por outro lado, o tratamento químico dos SRBCs com ácido tânico promove uma adsorção antigênica estável (passo de sensibilização) e independente do anticoagulante utilizado. O uso de 1% de BSA durante as lavagens dos SRBCs e na diluição dos antissoros incrementa a especificidade da IHA e, a combinação dos SRBCs tratados quimicamente com antígenos de H. parasuis termo-resistentes aumentam a resolução da IHA. Nossos resultados destacam uma melhoria na principal técnica de sorotipificação de H. parasuis, que auxiliará diretamente no entendimento da epidemiologia da Doença de Glässer e na caracterização dos sorovares envolvidos em surtos da doença.(AU)

Antibody response in silver catfish (Rhamdia quelen) immunized with a model antigen associated with different adjuvants

Adjuvants are essential to boost the immune response to inoculated antigen and play a central role in vaccine development. In this study, we investigated the efficacy of several adjuvants in the production of anti-bovine serum albumin (BSA) antibodies in silver catfish. Two hundred and seventy juvenile silver catfish (60–80 g) of both sexes were intraperitoneally vaccinated with BSA (200 µg/fish) alone or mixed to the following adjuvants: Freund’s complete adjuvant (FCA), Freund’s incomplete adjuvant (FIA), aluminum hydroxide (AlOH), Montanide, four types of cytosine-phosphate-guanine (CpG) oligodeoxynucleotides (ODNs) and three concentrations of β-glucan, and the immune enhancing property was evaluated by measuring anti-BSA antibodies in blood samples at biweekly intervals. Our results demonstrated that CpGs ODNs and β-glucan were as effective as classical adjuvants (FCA, FIA, AlOH and Montanide) in promoting anti-BSA antibodies and that the kinetics of antibody production induced by all adjuvants used in our study had a similar trend to that observed in other fish species, with a peak at 28 days post-vaccination. These results may be useful for the selection of adjuvants for vaccine formulation intended for silver catfish and for the development of vaccine and vaccination strategies to other fish species.

Inactivated Parapoxvirus ovis induces a transient increase in the expression of proinflammatory, Th1-related, and autoregulatory cytokines in mice

The immunostimulatory properties of inactivated Parapoxvirus ovis (iPPVO) have long been investigated in different animal species and experimental settings. In this study, we investigated the effects of iPPVO on cytokine expression in mice after intraperitoneal inoculation. Spleen and sera collected from iPPVO-treated mice at intervals after inoculation were submitted to cytokine mRNA determination by real-time PCR (qPCR), serum protein concentration by ELISA, and interferon (IFN)-α/β activity by bioassay. The spleen of iPPVO-treated animals showed a significant increase in mRNA expression of all cytokines assayed, with different kinetics and magnitude. Proinflammatory cytokines interleukin (IL)-1β, tumor necrosis factor-alpha (TNF-α), and IL-8 mRNA peaked at 24 hours postinoculation (hpi; 5.4-fold increase) and 48 hpi (3- and 10-fold increases), respectively. A 15-fold increase in IFN-γ and 6-fold IL-12 mRNA increase were detected at 48 and 24 hpi, respectively. Increased expression of autoregulatory cytokines (Th2), mainly IL-10 and IL-4, could be detected at later times (72 and 96 hpi) with peaks of 4.7- and 4.9-fold increases, respectively. IFN-I antiviral activity against encephalomyocarditis virus was demonstrated in sera of treated animals between 6 and 12 hpi, with a >90% reduction in the number of plaques. Measurement of serum proteins by ELISA revealed increased levels of IL-1, TNF-α, IL-12, IFN-γ, and IL-10, with kinetics similar to those observed by qPCR, especially for IL-12 and IFN-γ. These data demonstrate that iPPVO induced a transient and complex cytokine response, initially represented by Th1-related cytokines followed by autoregulatory and Th2 cytokines.

Embryonic and larval development of Jundiá (Rhamdia quelen, Quoy & Gaimard, 1824, Pisces, Teleostei), a South American Catfish

The jundiá (Rhamdia quelen, Quoy & Gaimard) is an endemic South American fish species. Because this species supports cold winters and grows faster during warm months, it has begun to be viewed as an ideal species for fish production in southern South America. In the present study, jundiá oocytes used were obtained by extrusion from females after hormone injection. Soon after hydration, the eggs were transferred to 50 L conic glass incubators, with constant and controlled water influx. Samples of fertilized eggs were transferred to Petri dishes and, examined under a stereoscopic microscope, were spherical, demersal, and non-adhesive with defined perivitelline space and resistant chorion. Cleavage stages occurred during the first 3.5 h. After hatching, larvae were transferred to 200 L glass fiber incubators. First signs of embryo movement were observed 21 h after fertilization; larval eclosion occurred 30.5 h after fertilization. Present findings may provide a basis for studies aimed at determining the complete ontogeny of jundiá and may be useful in eco-toxicological studies.

O jundiá (Rhamdia quelen, Quoy & Gaimard) é uma espécie endêmica da América do Sul. Por ser adaptada ao frio do inverno e ter um crescimento rápido durante os meses quentes, o jundiá é uma espécie adequada para aqüicultura no sul da América do Sul. Muitos aspectos da fisiologia reprodutiva, larvicultura, hematologia, fisiologia da resposta ao estresse, têm sido recentemente estudados. Os ovócitos utilizados neste estudo foram obtidos pela extrusão de fêmeas após indução hormonal. Logo após a hidratação, foram transferidos para incubadoras cônicas de vidro com capacidade para 50 L, com fluxo de água constante e controlado. Amostras de ovos fertilizados foram colocadas em placas de Petri e examinadas através de estereomicroscópio. Os ovos eram esféricos, demersais e não-adesivos, com espaço perivitelino definido e córion resistente. Os estágios de clivagem ocorreram durante as 3,5 primeiras horas. Após a eclosão, as larvas foram transferidas para incubadoras de fibra de vidro de 200 l. Os primeiros sinais de movimento embrionário foram observados 21 h após a fertilização, e a eclosão das larvas ocorreu 30,5 h após a fertilização. Estes resultados podem servir como base para muitos estudos, objetivando o conhecimento da ontogenia completa do jundiá, e para aplicação em estudos ecotoxicológicos.

Production and characterization of monoclonal antibodies to Brazilian isolates of bovine viral diarrhea virus

Three Brazilian isolates of bovine viral diarrhea virus (BVDV), antigenically distinct from the standard North American isolates, were selected to immunize BALB/c mice in order to obtain hybridoma cells secreting anti-BVDV monoclonal antibodies (mAbs). Two hybridoma clones secreting mAbs, reacting specifically with BVDV-infected cells (mAbs 3.1C4 and 6.F11), were selected after five fusions and screening of 1001 hypoxanthine-aminopterin-thymidine-resistant clones. These mAbs reacted in an indirect fluorescent antibody (IFA) assay with all 39 South and North American BVDV field isolates and reference strains available in our laboratory, yet failed to recognize other pestiviruses, namely the hog cholera virus. The mAbs reacted at dilutions up to 1:25,600 (ascitic fluid) and 1:100 (hybridoma culture supernatant) in IFA and immunoperoxidase (IPX) staining of BVDV-infected cells but only mAb 3.1C4 neutralized virus infectivity. Furthermore, both mAbs failed to recognize BVDV proteins by IPX in formalin-fixed paraffin-embedded tissues and following SDS-PAGE and immunoblot analysis of virus-infected cells, suggesting they are probably directed to conformational-type epitopes. The protein specificity of these mAbs was then determined by IFA staining of CV-1 cells transiently expressing each of the BVDV proteins: mAb 3.1C4 reacted with the structural protein E2/gp53 and mAb 6.F11 reacted with the structural protein E1/gp25. Both mAbs were shown to be of the IgG2a isotype. To our knowledge, these are the first mAbs produced against South American BVDV isolates and will certainly be useful for research and diagnostic purposes

Balanoposthitis in bulls due to bovine herpervirus in South Brazil

We describe an acute outbreak of balanoposthitis in bulls at an artificial insemination station in South Brazil. Bovine herpesvirus was isolated from preputial swabs in the Crandell feline kidney cell line and secondary fetal bovine lung cells and identified using the fluorescent antibody technique and electron microscopy. Polyclonal antibodies against the whole virus were used for identification of the bovine herpesvirus with the fluorescent antibody technique. Herpesvirus particles could be seen in the infected cells by electron microscopy. Eleven bulls had clinical signs resembling balanoposthitis and nine yelded virus