Elenice Maria Siquetin Cunha

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.

Antibodies against pseudorabies virus in feral swine in southeast Brazil

Soros de 358 javalis (Sus scrofa), criados em sistema de semiconfinamento em propriedades do estado de Sao Paulo, foram coletados entre 1998 e 2000 e testados para anticorpos contra o virus da doenca de Aujeszky (VDA), pela tecnica de soroneutralizacao (SN) e ensaio imunoenzimatico (ELISA). Foram detectados animais soropositivos em tres das sete propriedades analisadas. Do total de javalis testados, 30,7% apresentaram anticorpos neutralizantes contra o VDA, com variacao de 25,2% a 100% nas propriedades com animais sororreagentes. O ELISA detectou menor numero de sororeagentes (19,3%), sendo a sensibilidade e a especificidade 57,3% e 97,6%, respectivamente, e a correlacao observada de 85,2% (P<0,0001). Os resultados mostram que a infeccao pelo virus da doenca de Aujeszky ocorre em criacoes de javalis no estado de Sao Paulo, e compromete o sucesso de um futuro programa de erradicacao da doenca na regiao.

Ocorrência de equídeos soropositivos para os vírus das encefalomielites e anemia infecciosa no Estado de Mato Grosso

The present work evaluated the occurrence of seropositive equids for eastern encephalomyelitis virus (EEE), western encephalomyelitis virus (WEE), Venezuelan encephalomyelitis virus (VEE) and infectious anemia virus (IAV) in the Pantanal, Savannah and Amazon biomes of Mato Grosso State, Brazil. The detection of antibodies against IAV was carried out in 886 sera of equids by the immunodiffusion test, and antibodies against EEE, WEE and VEE were evaluated in 473 sera by the seroneutralization test performed in VERO cells. The results showed 46 IAV seropositive equids (5.1%). No sera was positive in the Amazon region, and the Pantanal biome showed a higher occurrence with 36.6% of seropositives (P 0.05). Despite that IAV was not observed in equids from the Amazon, the occurrence of seropositive equids agree with the Brazilian prevalence. The differences of EEE and VEE behavior between biomes reinforce the presence of animal reservoirs, along with environmental and weather characteristics that support vector maintenance, which favor the presence of the viral infection in Mato Grosso State.

PREVALENCE OF ANTIBODIES AGAINST INFLUENZA VIRUS IN NON-VACCINATED EQUINES FROM THE BRAZILIAN PANTANAL

The prevalence of antibodies against Equine Influenza Virus (EIV) was determined in 529 equines living on ranches in the municipality of Poconé, Pantanal area of Brazil, by means of the hemagglutination inhibition test, using subtype H3N8 as antigen. The distribution and possible association among positive animal and ranches were evaluated by the chi-square test, spatial autoregressive and multiple linear regression models. The prevalence of antibodies against EIV was estimated at 45.2% (95% CI 30.2 - 61.1%) with titers ranging from 20 to 1,280 HAU. Seropositive equines were found on 92.0% of the surveyed ranches. Equine from non-flooded ranches (66.5%) and negativity in equine infectious anemia virus (EIAV) (61.7%) were associated with antibodies against EIV. No spatial correlation was found among the ranches, but the ones located in non-flooded areas were associated with antibodies against EIV. A negative correlation was found between the prevalence of antibodies against EIV and the presence of EIAV positive animals on the ranches. The high prevalence of antibodies against EIV detected in this study suggests that the virus is circulating among the animals, and this statistical analysis indicates that the movement and aggregation of animals are factors associated to the transmission of the virus in the region.

Análise filogenética de isolados do vírus da raiva de herbívoros na fronteira de Minas Gerais e São Paulo (2000-2009), Brasil

Rabies transmitted by the hematophagous bat Desmodus rotundus represents a public health concern and a burden for the Brazilian livestock industry. Current evidence suggests that rabies occurrence is related to landscape characteristics, topography, hydrography, animal production systems and land use. However, a few studies have analyzed the possible connections among geographic factors and the molecular diversity of the rabies virus, furthering the understanding of the spatial and temporal dynamics of outbreaks. A study reported that the latest rabies epizootics in herbivores reported in the eastern region of Sao Paulo (close to the Minas Gerais border) occurred in two epidemic waves; the first was before 1998, and the other occurred after 1999. Using this evidence, the aim of the present study was to analyze cases of rabies in herbivores in the southern region of Minas Gerais (2000-2009) and their possible relationship with the aforementioned epidemics, considering the geographic characteristics of the region. Partial sequences of glycoprotein (539 nt) and nucleoprotein genes (414 nt) were obtained from 31 rabies virus isolates from herbivores. A phylogenetic tree was proposed for each genomic region using the Neighbor joining method, fixing the Kimura 2-parameter evolution model with a bootstrap level of 1,000 replications. Genetic sublineages were plotted on maps, considering rabies risk areas for herbivores in Sao Paulo, as well as topographic characteristics and hydrographic basins, to visualize any apparent distribution pattern influenced by those features. The phylogenetic trees had concordant topologies, suggesting a possible common origin for rabies outbreaks in herbivores along the SP/MG border, surrounding the less elevated portions of the Serra da Mantiqueira and along the hydrographic basins of Piracicaba/Jaguari, Paranaiba do Sul, Grande, Pardo and Mogi-Guacu rivers.The co-circulation of several viral lineages was observed in some municipalities, possibly due to an overlapping of rabies outbreaks. Inferred protein sequences of both genes showed synonymous mutations, except among residues 20 to 200, corresponding to the external domain of the glycoprotein. This information prompted cooperation among the animal health services of both states to reinforce rabies control in the border area.