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| Author(s): |
Lilian Giotto Zaros
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2007-02-27 |
| Examining board members: |
Luiz Lehmann Coutinho;
Alessandro Francisco Talamini do Amarante;
Flavio Vieira Meirelles;
Irineu Umberto Packer;
Luciana Correia de Almeida Regitano
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| Advisor: | Luiz Lehmann Coutinho |
| Abstract | |
The aim of this work was identify genes related to immune response to gastrointestinal nematodes in cattle. The periodic counts of eggs per gram (EPG) of feces and coproculture analysis were done to identify the resistant and susceptible animals. The EPG counts allowed us to identify these animals. It was twenty-fold higher in susceptible group (P<0.001). The coproculture analysis allowed us to conclude that the infestation is predominantly characterized byCooperia spp. and Haemonchus spp. and a low incidency of Oesophagostomum. To identify the genes, it was used the EST (Expressed Sequence Tags) methodology and constructed two cDNA libraries from abomasum, abomasum lymph nodules and small intestine from resistant (ER1) and susceptible (ES1) cattle. It was generated 2496 ESTs from each library. From these, 1664 and 1898 ESTs were valids to ER1 and ES1 libraries, respectively. Among the 2323 unique sequences were identifyed several genes related to immune response, such as MHC class I and II molecules, immunoglobulins, interleukins, lysozyme and pepsinogen. To study the gene expression, it was used the reverse transcription and real-time polymerase chain reaction methodology to quantify the messager RNA expression of 10 genes related to polarization of immune response (the interleukins IL-2, IL-4, IL-8, IL-12p35 e IL-13, the cytokines TNF-β, IFN- γ, MCP-1β and MCP-2 and the glycoprotein mucin 1-MUC1). The gene expression analysis in the abomasum reveled that IL-4 (P<0,018) and IL-13 (P<0,002) were up-regulated and TNF-β (P<0,0001) was down-regulated in resistant group; in the abomasum lymph nodules IL-4 (P<0,019) and IFN-γ (P<0,007) were both up-regulated in resistant and susceptible group, respectively; in the small intestine IL-4 (P<0,01) and IL-13 (P<0,045) were up-regulated in resistant group and IL-2 (P<0,047), IL-12p35 (P<0,029), IFN-γ (P<0,004) and MCP-1 (P<0,03) were down-regulated in susceptible one. In the abomasum from resistant group, pepsinogen was down-regulated (P<0,025) and lysozyme was up-regulated (P<0,042). In conclusion, the strategy used allowed us to identify several genes involved in immune response and the inedit discovery that Bos indicus resistant to gastrointestinal nematodes present a TH2-type response, in contrast to susceptible animals that present a TH1-type response. (AU) | |