| Infectious bursal disease virus (IBDV) causes an immunosuppressive disease in chickens and leads to economic losses in the poultry industry. The virus has a bisegmented RNA genome, which codifies 5 proteins (VP1 to VP5). VP2 constitutes the outer capsid and contains conformational neutralizing epitopes. Forty-eight bursa samples were collected from IBDV infected commercial broiler flocks in the US. The samples were tested by Real-Time RT-PCR using probes designed for two epitope regions denominated minor peak I and peak B and subsequently sequenced. The probes were complementary to nucleotide sequences of Del-E, STC and F15 IBDV strains. It was observed that 23, 48 and 44 samples tested with the minor peak probes, respectively, had a lower melting temperature (Tm) than expected. On the other hand, 44, 41 and 48 samples tested with the probes designed for peak B also had a lower Tm. The nucleotide sequencing revealed that most of the samples that had shifts in their melting temperatures (Tm) when tested by real-time RT-PCR had nucleotide mutations when were sequenced. Additionally, most of the mutations resulted in amino acid substitutions and to different amino acid groups. Consequently, these mutations may be responsible for antigenic changes. In order to improve vaccination efficacy it is necessary to employ vaccines based on the antigenic subtypes present in the flock's environment. RT-PCR can infer the presence of IBDV variants, which may assist in the development of effective vaccination strategies.; IBDV induced immunosuppression is reported to increase susceptibility to pathogens such as Salmonella spp., E. coli and other food-borne pathogens. A study was designed to attempt to establish a possible correlation between IBDV-induced immunosuppression and Campylobacter jejuni colonization and shedding in chickens. Colonies that resembled Campylobacter jejuni were submitted to PCR to confirm the diagnosis. It was observed that the groups inoculated with C. jejuni and IBDV displayed a prolonged shedding and higher amounts of C. jejuni which were significantly different when compared to the other groups. The results indicated that IBDV-induced immunosuppression exacerbates C. jejuni shedding and colonization in chickens. These observations support the idea that IBDV may have an indirect impact on food-borne diseases and reinforce the importance of IBDV control in commercial flocks. (Abstract shortened by UMI.)... |
