Comparison among three different serological methods for the detection of equine influenza virus infection.

The equine influenza virus (EIV) H3N8 subtype is responsible for all EIV outbreaks worldwide while the H7N7 subtype is less pathogenic and is considered extinct as it has not been confirmed in outbreaks since 1980. Although EIV is enzootic in Brazil, few reports describe the actual EIV antibody status in the country. The aims of this study were: - to evaluate the efficiency of different serum treatments described by the World Organisation for Animal Health (OIE) and the World Health Organization (WHO) to remove non-specific haemagglutination inhibitors for the haemagglutination inhibition (HI) assay for EIV - to evaluate the presence of EIV antibodies by HI, enzyme-linked immunosorbent assay and agar gel immunodiffusion in 83 non-vaccinated equines from São Paulo State - to evaluate a strategy to better analyse equine sera for EIV antibodies. Although there was no statistical difference among treatments, receptor-destroying enzyme treatment followed by chicken erythrocyte adsorption showed more consistent results, which corroborate the OIE and WHO recommendation to use this treatment preferentially. The HI results suggest equine H3N8 virus circulation among the animals tested from São Paulo State. The algorithm suggested here could be used to guide antibody detection against equine influenza virus in equines, improving the test specificity by aiming to avoid false positive results.

Tous les foyers de grippe équine dans le monde sont dus au sous-type H3N8 du virus. Le sous-type H7N7, moins pathogène, est considéré comme éteint, sa présence n'ayant été confirmée dans aucun des foyers enregistrés depuis 1980. Au Brésil, la grippe équine est enzootique mais la prévalence d'anticorps dans le pays est peu documentée. La présente étude avait trois objectifs : ­ évaluer l'efficacité de plusieurs traitements de sérums décrits par l'Organisation mondiale de la santé animale (OIE) et l'Organisation mondiale de la santé (OMS) sur la suppression des inhibiteurs d'hémagglutination non spécifiques, afin de pouvoir utiliser l'épreuve d'inhibition de l'hémagglutination pour la détection de la grippe équine, ­ évaluer la présence d'anticorps dirigés contre la grippe équine chez 83 chevaux non vaccinés de l'état de São Paulo en utilisant l'inhibition de l'hémagglutination, l'épreuve immuno-enzymatique (ELISA) et l'épreuve d'immunodiffusion en gélose (IDG) ; ­ évaluer une stratégie visant à améliorer les techniques sérologiques de détection des anticorps dirigés contre la grippe équine. S'il n'y a pas eu de différence statistique significative entre les traitements, celui faisant appel à l'enzyme de destruction du récepteur suivi d'une adsorption sur érythrocytes de poule a permis d'obtenir les résultats les plus cohérents, ce qui corrobore les recommandations de l'OIE et de l'OMS en faveur de ce traitement. Les résultats obtenus au moyen de l'inhibition de l'hémagglutination indiquent que le virus H3N8 est présent parmi les animaux testés de l'état de São Paulo. L'algorithme présenté par les auteurs pourrait servir de modèle pour détecter la présence d'anticorps dirigés contre le virus de la grippe équine chez les chevaux : en effet, il permet d'éviter les résultats faussement positifs, ce qui améliore la spécificité du test utilisé.

El subtipo H3N8 del virus de la gripe equina (VGE) es el agente etiológico de todos los brotes que se producen en el mundo, mientras que el subtipo H7N7, menos patogénico, se da por extinto, en la medida en que desde 1980 no se ha confirmado su intervención en brote alguno. Aunque en el Brasil el VGE es enzoótico, existen pocos trabajos que den cuenta de la situación real del país en cuanto a la presencia de anticuerpos contra el virus. Los autores describen un estudio que perseguía los siguientes objetivos: ­ evaluar la eficacia de distintos tratamientos séricos descritos por la Organización Mundial de Sanidad Animal (OIE) y la Organización Mundial de la Salud (OMS) para eliminar los inhibidores inespecíficos de la hemaglutinación con objeto de aplicar la técnica de inhibición de la hemaglutinación a la detección del VGE; ­ evaluar la presencia de anticuerpos contra el VGE por inhibición de la hemaglutinación, ensayo inmunoenzimático (ELISA) e inmunodifusión en gel de agar en 83 ejemplares equinos no vacunados del estado de São Paulo; ­ evaluar una estrategia encaminada a analizar más eficazmente sueros equinos para detectar en ellos anticuerpos anti-VGE. Aunque no se observaron diferencias estadísticamente significativas entre los tratamientos, el uso de enzimas destructores de receptores seguido de la técnica de adsorción de eritrocitos de pollo arrojó resultados más coherentes, cosa que avala la recomendación de la OIE y la OMS de privilegiar este tratamiento. Los resultados obtenidos por inhibición de la hemaglutinación parecen indicar que el virus H3N8 equino circula entre los animales analizados del estado de São Paulo. El algoritmo aquí propuesto podría servir de guía para detectar en equinos la presencia de anticuerpos contra el VGE. Puesto que apunta a evitar falsos positivos, su aplicación mejoraría la especificidad de la prueba.

Equid herpesvirus type-1 exhibits neurotropism and neurovirulence in a mouse model.

Intranasal inoculation of equid herpesvirus type-1 (EHV-1) Brazilian strains A4/72 and A9/92 induced an acute and lethal infection in four different inbred mouse strains. Clinical and neurological signs appeared between the 2nd and 3rd day post inoculation (dpi) and included weight loss, ruffled fur, a hunched posture, crouching in corners, nasal and ocular discharges, dyspnoea, dehydration and increased salivation. These signs were followed by increased reactivity to external stimulation, seizures, recumbency and death. The virus was recovered consistently from the brain and viscera of all mice with neurological signs. Histopathological changes consisted of leptomeningitis, focal haemorrhage, ventriculitis, neuronal degeneration and necrosis, neuronophagia, non-suppurative inflammation, multifocal gliosis and perivascular infiltration of polymorphonuclear and mononuclear cells. Immunohistochemical examination demonstrated that EHV-1 strains A4/72 and A9/92 replicated in neurons of the olfactory bulb, the cortex and the hippocampus. In contrast, mice inoculated with the EHV-1 Brazilian strain A3/97 showed neither weight loss nor apparent clinical or neurological signs; however, the virus was recovered consistently from their lungs at 3 dpi. These three EHV-1 strains showed distinct degrees of virulence and tissue tropism in mice. EHV-1 strains A4/72 and A9/92 exhibited a high degree of central nervous system tropism with neuroinvasion and neurovirulence. EHV-1 strain A3/97 was not neurovirulent despite being detected in the brains of infected BALB/c nude mice. These findings indicate that several inbred mouse strains are susceptible to neuropathogenic EHV-1 strains and should be useful models for studying the pathogenesis and mechanisms contributing to EHV-induced myeloencephalopathy in horses.

First detection of the equine herpesvirus 1 neuropathogenic variant in Brazil.

This report describes the first detection of an equine herpesvirus 1 (EHV-1) neuropathogenic variant (G2254/D752) in Brazil from a case of fatal equine herpesvirus myeloencephalopathy (EHM) in a mare. The results of nucleotide sequencing of the EHV-1 ORF30 gene showed that two other Brazilian EHV-1 isolates from EHM cases are representatives of the non-neuropathogenic variant (A2254/N752), suggesting that other unidentified factors are probably also involved in the neuropathogenicity of EHV-1 in horses. These findings will contribute to the epidemiological knowledge of EHV-1 infection in Brazil.

Granulomatous meningomyeloencephalitis in a calf caused by Mycobacterium bovis / Meningomieloencefalite granulomatosa em um bezerro, causada por Mycobacterium bovis

Bovine tuberculosis is a chronic disease caused by Mycobacterium bovis, characterized by respiratory disorders, emaciation and lymphadenomegaly. Neurological signs associated with granulomatous lesions in the central nervous system are rarely seen. In Brazil, the National Program for Control and Eradication of bovine tuberculosis has begun in 2001, and notification of the disease is compulsory. A case of tuberculous meningomyeloencephalitis is reported in a dairy calf less than one year old presenting neurological signs (irritability, aggressiveness, weakness, dizziness and recumbency) which progressed to death in three days. Brain, spinal cord, and lung tissue samples were examined histopathologically. The spinal cord showed granulomatous meningomyelitis with Langhans giant cells in the meninges and perivascular mononuclear cuffing in the white and gray matter. There were a few granulomas in the cerebral cortex with a central area of necrosis surrounded by mononuclear infiltrate. Mononuclear perivascular cuffing, satellitosis, hyperemia, and severe granulomatous meningitis with Langhans giant cells were observed in the neuropile. Samples of brain were inoculated into Petragnani and Stonebrink media. M. bovis was isolated and identified by PCR with JB21-JB22 primers. Considering the 2,888 samples of bovine CNS sent for surveillance of neurological syndrome and negative for Rabies, this was the only case of tuberculous meningomyeloencephalitis (0,035%) diagnosed from 2004 to 2008 by the Laboratory of Anatomopathology of Instituto Biológico. Although tuberculous meningomyeloencephalitis is not so frequent, it's important to diagnose M. bovis as a causative agent of bovine neurological disorders. In accordance with Brazilian regulations, sanitary measures in the infected herd (test-and-slaughter) should be adopted.

A tuberculose bovina é uma doença crônica causada por Mycobacterium bovis, caracterizada por desordens respiratórias, emaciação e linfadenomegalia. Em raros casos, sinais neurológicos associados com lesões granulomatosas no sistema nervoso central são observados. O Brasil iniciou o Programa Nacional para Controle e Erradicação dessa doença em 2001, tornando a notificação compulsória. Um caso de meningomieloencefalite tuberculosa é relatado em uma bezerra leiteira com um ano de idade, que apresentou sinais neurológicos (irritabilidade e agressividade, fraqueza e tontura, decúbito) que progrediram para morte em três dias. A medula espinhal apresentou meningomielite granulomatosa, com células gigantes tipo Langhans nas meninges e manguito perivascular mononuclear na substância branca e cinzenta. Havia alguns granulomas no córtex cerebral, com área central de necrose circundada por infiltrado mononuclear. No neurópilo observou-se manguito perivascular mononuclear, satelitose, hiperemia e severa meningite granulomatosa com células gigantes tipo Langhans. Amostras de cérebro foram inoculadas nos meios de cultivo Petragnani e Stonebrink e M. bovis foi isolado e identificado por PCR com primers JB21-JB22. Considerando as 2.888 amostras de SNC bovino enviadas para a vigilância epidemiológica de síndrome neurológica e negativas para raiva, este foi o único caso (0,035%) de meningomieloencefalite tuberculosa diagnosticado pelo Laboratório de Anatomia Patológica do Instituto Biológico no período de 2004 a 2008. Embora a meningomieloencefalite tuberculosa não seja tão freqüente, é importante incluir a infecção por M. bovis no diagnóstico diferencial de lesões do sistema nervoso central de bovinos. De acordo com a legislação brasileira, medidas sanitárias no rebanho infectado (teste e abate) devem ser adotadas.

A unique substitution at position 333 on the glycoprotein of rabies virus street strains isolated from non-hematophagous bats in Brazil.

The amino acid R or K at position 333 on the glycoprotein of the rabies virus is considered necessary for virulence in adult mice. Although some exceptions exist, substitution at this position causes expression of a phenotype that is either less pathogenic or non-virulent. To date, such substitutions have only been found in fixed strains of rabies virus. In this study, the authors found 333H, 333N, and 333Q substitutions at this position in rabies virus street strains isolated from non-hematophagous bats in Brazil. These strains showed pathogenicity and lethality on passage using adult mice with the intracerebral route and were confirmed rabies-positive by immunofluorescent assay. This suggests that these strains maintain virulence. Our findings indicate that rabies virus street strains with these substitutions exist in the field and may result in infection cycles.

Genetic diversity of bat rabies viruses in Brazil.

Thirty-three Brazilian bat rabies viruses (RVs) were studied by sequence analysis and were compared against sequences of bat-related RVs from other regions of the Americas. Phylogenetic analysis revealed that bat-related RVs formed several monophyletic lineages and that these were associated with bat species. Brazilian bat RVs were found to include nine major lineages, one of which grouped with RVs isolated from Lasiurus spp. from different regions of the Americas. These results suggest that there is considerable diversity among Brazilian bat RV variants and that some of these RV variants may be associated with bats from other countries.

Antibodies against pseudorabies virus in feral swine in southeast Brazil / Anticorpos contra o vírus da doença de Aujeszky em javalis no estado de São Paulo

Serum samples collected from 358 wild boars (Sus scrofa) in breeding farms in São Paulo, southeast Brazil, from 1998 to 2001, were tested for antibodies against pseudorabies virus (PRV) by means of serum neutralization (SN) and enzyme-linked immunobsorbent assay (ELISA). Seropositive animals were detected in three of seven herds analyzed. Overall seroprevalence as assessed by SN was 30.7 percent, ranging from 25.2 percent to 100 percent for the herds that presented seropositive animals. Indirect ELISA detected lower seroprevalence (19.3 percent). Sensitivity and specificity of ELISA were equal to 57.3 percent and 97.6 percent, respectively. Agreement was equal to 85.2 percent (P<0.0001). These results showed that PRV infections occurred in farmed feral swine in southeast Brazil, and affect pseudorabies eradication program.

Soros de 358 javalis (Sus scrofa), criados em sistema de semiconfinamento em propriedades do estado de São Paulo, foram coletados entre 1998 e 2000 e testados para anticorpos contra o vírus da doença de Aujeszky (VDA), pela técnica de soroneutralização (SN) e ensaio imunoenzimático (ELISA). Foram detectados animais soropositivos em três das sete propriedades analisadas. Do total de javalis testados, 30,7 por cento apresentaram anticorpos neutralizantes contra o VDA, com variação de 25,2 por cento a 100 por cento nas propriedades com animais sororreagentes. O ELISA detectou menor número de sororeagentes (19,3 por cento), sendo a sensibilidade e a especificidade 57,3 por cento e 97,6 por cento, respectivamente, e a correlação observada de 85,2 por cento (P<0,0001). Os resultados mostram que a infecção pelo vírus da doença de Aujeszky ocorre em criações de javalis no estado de São Paulo, e compromete o sucesso de um futuro programa de erradicação da doença na região.

Eficácia de vacina inativada contra a doença de Aujeszky: infecçäo experimental de suínos / Efficacy of an inactivated Aujeszky's disease virus vaccine: experimental infection of pigs

Um, vacina experimental contra a doença de Aujeszky (DA), inativada e adsorvida em adjuvante oleoso, foi testada em relaçäo á induçäo de imunidade, grau de proteçäo clínica e capacidade de reduzir a infecçäo, após desafio pela via intranasal. Grupos de 6 suínos, com 45 dias de idade, foram vacinados com uma ou duas doses de vacina, pelas vias intramuscular ou subcutânea, sendo mantido um grupo-testemunha, sem vacinaçäo. Todos os suínos vacinados apresentaram títulos de anticorpos neutralizantes, detectáveis através da prova de soroneutralizaçäo, sendo estatisticamente superiores nos animais que receberam duas doses de vacina. A vacinaçäo preveniu as manifestaçöes clínicas da doença após desafio, principalmente nos animais que receberam duas doses de vacina quando comparado com os que receberam 1 dose. Em todos os animais, vacinados e näo-vacinados, foi possível a detecçäo do vírus da doença de Aujeszky (VDA) nas amígdalas, através da técnica de imunofluorescência direta. A porcentagem de amígdalas positivas nos suínos vacinados com duas doses foi inferior quando comparada àquela de suínos näo-vacinados, no 2º e 7º dias pós-infecçäo. Em suínos vacinados com duas doses de vacina, pela via subcutânea, a taxa de infecçäo foi estatisticamente menor que naqueles vacinados com uma dose, pelas vias intramuscular ou subcutênea, e näo-vacinadas