Meningoencephalitis caused by Bovine herpesvirus type 5 (BoHV-5) is responsible for heavy economic losses in the cattle industry. As in other Alphaherpesviruses, the envelope glycoprotein IV (gD), which mediates penetration into host cells, is one of the major candidate antigens for a recombinant vaccine, since it induces a strong and persistent immune response. The DNA coding for a truncated form of BoHV-5 gD (tgD) has been cloned into the Pichia pastoris expression vector pPICZalphaB to allow protein secretion into the medium. After induction with methanol, a approximately 55kDa protein was obtained. Enzyme deglycosylation with Endo H showed a smaller size band in SDS-PGAE, with approximately 50kDa, suggesting that tgD has N-linked oligosaccharides and that it is not hyperglycosylated. The approximately 55kDa protein was recognized by several polyclonal antibodies, including polyclonal antibody anti-tgD and polyclonal antibodies of different animal species immunized with BoHV-5 and BoHV-1. This is the first report of BoHV-5 gD expression in yeast. It was shown that the recombinant truncated form of BoHV-5 gD has antigenic and immunogenic properties similar to the native BoHV-5 gD. Expression of tgD as a secreted protein allows simple and inexpensive purification methods that can be used for further studies to evaluate its immunogenicity in cattle.
This study aimed to verify the influence of bovine genetic resistance on biological traits of the Rhipicephalus (Boophilus) microplus tick. Genetic resistance or susceptibility was determined according to breeding values for tick counts, predicted using a dataset of 9007 Hereford and Braford (Hereford×Zebu) bovines naturally infested and raised under extensive production systems in southern Brazil. From a total of 974 Braford heifers born in 2008, 20 were classified as genetically tick-resistant and 20 classified as genetically tick-susceptible, and used to obtain the ticks samples used in this study. The 40 heifers were exposed to four subsequent artificial infestations with approximately 20,000 larvae at 14-day intervals. From the 19th to 23rd day of each infestation tick counts were performed on the left body side of the heifers. Engorged ticks were manually collected on the day of highest observed burden after each infestation. Tick counts on susceptible heifers were 5.5, 10.5, 11.1 and 6.9 times larger than on resistant heifers, respectively, after the first, second, third and fourth artificial infestations. In the third infestation, ticks from resistant heifers showed lower egg production index (P<0.0001) than ticks from susceptible heifers. In the fourth infestation, ticks from susceptible group showed higher egg mass weight (P<0.05) and nutrient index (P<0.0001) than ticks from resistant heifers. Tick initial weights showed a positive association with egg production index in susceptible heifers (P<0.05) and a negative association in the resistant group (P<0.05), suggesting a host defense mechanism that reduces the conversion efficiency of ingested blood to eggs in engorged ticks from resistant cattle. This shows that bovine genetic tick resistance, in addition to affecting the number of ticks carried by the animals, also affected the egg mass weight, egg production and nutrient indexes of ticks. The results of the present study imply that the selection of resistant animals could be used as a strategic tool for tick control in production systems, reducing infestation levels on cattle and environment.
Foram examinadas, pelo Laboratório de Doenças Parasitárias (LADOPAR) da Universidade Federal de Pelotas, 2.680 amostras de fezes de ovinos, advindas da região sul do estado do Rio Grande do Sul, Brasil, entre os anos de 2015 a 2017. A técnica coproparasitológica de Gordon & Whitlock (1939) foi utilizada para o diagnóstico. Das amostras analisadas, 86,5% apresentaram-se positivas para algum helminto gastrintestinal e oocistos de protozoários, sendo a infecção mais prevalente por ovos da ordem Strongylida. Através dos resultados obtidos, conclui-se que helmintoses gastrintestinais estão presentes nas criações de ovinos da região sul do estado e, através de exames coprológicos, é possível implementar medidas sanitárias e preventivas nos rebanhos.
O parasitismo pelo carrapato Rhipicephalus (Boophilus) microplus em países tropicais e subtropicais é associado a grandes quedas nos índices de produtividade dos rebanhos. O controle convencional do parasita, baseado na utilização de drogas carrapaticidas, há anos vem demonstrando sua ineficácia como estratégia de controle a longo prazo, através dos recorrentes relatos de populações de ectoparasitas resistentes às formulações comercialmente disponíveis. A ocorrência de variabilidade genética para resistência ao carrapato em bovinos indica a possibilidade de ganhos genéticos pela seleção de animais resistentes e o uso desta ferramenta como estratégia auxiliar no controle efetivo do parasita. O objetivo do presente estudo é apresentar resultados de estudos avaliando a resistência de bovinos ao carrapato, identificar fatores não genéticos que afetam os fenótipos de resistência, e descrever algumas descobertas na área da genética molecular que poderão auxiliar no processo de identificação de animais resis-tentes.
RESUMO
A piroplasmose equina causada por Theileria equi acomete os equinos de forma endêmica no Brasil e em diversos outros países tropicais e subtropicais. Considerada uma das mais
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