RESUMOO objetivo deste trabalho foi determinar a prevalência das infecções latentes por BoHV-1 e por BoHV-5 em bovinos de corte criados no Estado do Paraná. Os gânglios do nervo trigêmeo foram coletados de 400 bovinos hígidos, entre 18 e 36 meses de idade, provenientes de 90 propriedades rurais localizadas em diferentes mesorregiões geográficas do Estado e abatidos em frigorífico com Serviço de Inspeção Federal. A reação em cadeia da polimerase com amplificação do gene que codifica a glicoproteína C foi empregada para a detecção do DNA viral. Cento e nove bovinos eram herpéticos (27,25%), sendo 14,25% (57/400) infectados com BoHV-1, 9,75% (39/400) infectados com BoHV-5 e 3,25% (13/400) portadores de infecção mista. A distribuição geográfica foi heterogênea e as infecções foram mais prevalentes nas mesorregiões localizadas ao norte do Estado. A vigilância para a encefalite por BoHV-5 deve ser intensificada na mesorregião Noroeste.

ABSTRACTThe prevalence of latent infection with BoHV-1 or BoHV-5 in beef cattle raised in the state of Paraná, Brazil, was studied. The trigeminal ganglia were collected in a slaughterhouse from 400 healthy cattle, 18 to 36 months old, raised in 90 farms located in distinct geographical regions of the state. Polymerase chain reaction for amplification of the gene encoding C glycoprotein was performed to detect virus DNA. One hundred and nine (27.25%) animals were herpetic; 14.25% (57/400) were infected with BoHV-1, 9.75% (39/400) were infected with BoHV-5 and 3.25% (13/400) had mixed infection. The geographical distribution was heterogeneous and the infections were more prevalent in the north of the state. The surveillance for BoHV-5 encephalitis should be intensive in the Northwest region.

Natural (NV) and Cobalto60-irradiated (IrV) Crotalus durissus terrificus venom were used to evaluate serum production capacity of sheep and possible hematological and biochemical effects. Freeze-dried venom aliquots were diluted in acidified saline solution (NaCl 150 mM, pH 3.0) and irradiated by a Cobalt 60 source at a dose of 5.54 x 102 Gy/h and a concentration of 2.000 Gy. Twelve sheep were divided into two groups of six animals. One group received irradiated venom (IrV) and the other natural venom (NV). Three antigen doses (venom) were administered at monthly intervals. Blood samples were collected weekly for analysis of serum neutralization potency and capacity, complete blood count (CBC), total plasma protein, fibrinogen, albumin, and globulin. At the end of the experiment, the animals were challenged with a LD50 for sheep and showed no signs of envenoming. The two groups did not present clinical alterations. Results of the total leukocyte count did not present interaction or time factor effect for both groups, but there was a different action between them, with the NV group presenting more cells than the IrV group. The leukocyte increase to 13,000/ml indicates that slight leukocytosis occurred in the week after the first inoculation in the NV group. There was no statistically significant difference between groups in the absolute count of segmented neutrophils, eosinophils, and lymphocytes but there were statistically significant oscillations in values at the different collecting times. The NV group presented an increase in the absolute neutrophil count after the first inoculation that persisted for 5 weeks. In the IrV group, the increase in neutrophils occurred only in the first week returning to normal in the following weeks. The alterations in the neutrophil count are indicative of systemic inflammatory response related to cytokine release; response was more marked in the NV group, showing its greater toxicity.

The aim of this work was to investigate antigen irradiation on crotalic antivenom and the capacity of sheep as serum producers. Twelve sheep in two groups of six were inoculated with Crotalus durissus terrificus venom. One group was inoculated with natural venom (NV) and the other with Cobalt 60 gamma-irradiated venom (IrV). Three antigen doses were given to the animals at monthly intervals for immunization. The toxic activity of the venom was assessed by LD50 determination in mice. Blood samples were collected weekly analyses of serum neutralization capacity and potency. At the end of the experiment, the animals were challenged with a LD50 for sheep showed no signs of envenoming. These results showed that toxicity of the irradiated venom was 4.4 times less than the natural venom. The sera from the irradiated group neutralized LD50 14.6 times, and the sera from the natural group 4.4 times. Sera from the irradiated group were five times more potent. The two groups did not present clinical alterations. The results of this study show the potential for using sheep in crotalic antivenom production. The use of irradiated venom in sheep immunization induces a powerful and lasting humoral immune response shown by both the in vitro neutralization and potency tests and by the indirect ELISA antibody level detection technique.