Biochemical changes in cultivars of sweet oranges infected with citrus tristeza virus / Mudanças bioquímicas em vários cultivares de laranjas doces infectadas com o vírus citrus tristeza

Abstract Citrus fruit production occupies a place of considerable importance in the economy of the world including Pakistan. Tristeza disease caused by Citrus Tristeza Virus (CTV) exists in various forms that may or may not cause symptoms in the plants. The bioactive compounds and antioxidants are naturally present in plants and provide a defense mechanism that is generally accelerated in response to a stress. The objective of the present study was to target and analyze the citrus plants that were CTV positive to observe the changes in the enzymatic and non-enzymatic antioxidants of citrus (Sweet Oranges only). It was observed that in response to CTV infection, both the non-enzymatic antioxidants (total flavonoid, ascorbic acid, phenolic acid) and enzymatic antioxidants (catalase, superoxide dismutase and peroxidase) activities showed an increasing trend overall. The profiling of antioxidants in response to a viral infection may help in the discovery of new biomarkers that can be used as a monitoring tool in disease management.

Resumo As frutas cítricas ocupam um lugar de considerável importância na economia do Paquistão, assim como o resto do mundo. A doença da tristeza causada pelo Vírus da Tristeza dos Citros (CTV) existe em várias formas que podem ou não apresentar sintomas nas plantas. Os compostos bioativos e antioxidantes estão naturalmente presentes nas plantas e fornecem um mecanismo de defesa que é geralmente acelerado em resposta a um estresse. O objetivo do presente estudo foi analisar as alterações causadas pelo CTV nos antioxidantes enzimáticos e não enzimáticos de laranjas doces. Foi observado que, em resposta ao ataque de CTV, os antioxidantes não enzimáticos como flavonoides totais, ácido ascórbico, ácido fenólico e antioxidantes enzimáticos, como as atividades de catalase, superóxido dismutase e peroxidase, geralmente mostram uma tendência crescente. O perfil de antioxidantes em resposta a um ataque viral pode ajudar na descoberta de novos biomarcadores que podem ser usados ​​como uma ferramenta de monitoramento no gerenciamento de doenças.

Production of polyclonal and monoclonal antibodies against citrus tristeza virus and their efficiency for the detection of the virus / 生物工程学报

Citrus tristeza virus (CTV) was purified from a citrus sample by a modified protocol, and the yield was about 1 mg from 100 g citrus tissues. Polyclonal antibody was prepared by immunizing rabbits with the purified CTV preparation with a titer 1:25600 in indirect ELISA test. Eighteen hybridoma-cell lines secreting monoclonal antibodies (MAbs) against CTV were screened after the fusion of mouse myeloma cells (SP2/0) with spleen cells from BALB/c immunized with the virus preparation. Four hybridoma-cell lines were selected randomly for later analysis. The results indicated that the titers of ascetic fluids against these hybridoma cell lines ranged from 1:51200 to 1:204800 in indirect ELISA, and their isotypes and subclasses were IgG2a for 2G and 3H and IgG2b for IE and 4H. These four Mabs were used to detect CTV in citrus samples in different sources. Results showed that TAS-ELISA with polyclonal antibody as trapping antibody and monoclonal antibody as testing antibody had a higher specificity and sensitivity than PAS-ELISA. Four Mabs showed different intensities of serological reaction with different CTV isolates. However, much work remains for realizing the characteristics and the serological relationships among these isolates.