Direct detection of infectious bursal disease virus from clinical samples by in situ reverse transcriptase-linked polymerase chain reaction.

The presence of the very virulent (vv) Brazilian strain of infectious bursal disease virus (IBDV) was determined in the bursa of Fabricius, thymus and liver of 2-week-old broilers from a flock with a higher than expected mortality. For this purpose, a direct in situ reverse transcriptase (RT)-linked polymerase chain reaction (PCR) method was developed using specific primers for vvIBDV. Unlabelled forward and reverse biotinylated oligonucleotides were used for RT-PCR in a one-step method and the respective products were revealed by a direct enzymatic reaction. The results were compared with those obtained by standard RT-PCR using general primers for IBDV and virus isolation. The virus isolation, RT-PCR and in situ RT-PCR revealed positive results on the bursa of Fabricius in 86%, 80% and 100%, respectively. The in situ RT-PCR detected vvIBDV in all tested thymus and liver samples, whereas the standard RT-PCR detected virus in 80% and 90% of the samples, respectively. After three consecutive passages on chicken embryonated eggs, IBDV was isolated from 64% of the thymus samples and 30% of the liver samples. In the present study, no classical or antigenic variants of IBDV were detected. The developed in situ RT-PCR assay was able to detect the very virulent strain of IBDV with a higher sensitivity than the conventional RT-PCR and virus isolation.

Infection by Mycoplasma spp., feline immunodeficiency virus and feline leukemia virus in cats from an area endemic for visceral leishmaniasis.

BACKGROUND: Visceral leishmaniasis (VL) has been increasingly recognized in cats living in areas endemic for the disease. Co-infection with Leishmania infantum and other infectious agents is well established in dogs. However, for cats, data on co-infections with L. infantum and other infectious agents are still sparse. The aim of this study was to identify the prevalence of vector-borne pathogens, Mycoplasma spp., feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) in cats from an area endemic for VL in southeastern Brazil. RESULTS: Of the 90 cats, eight (8.9%) were infected with Mycoplasma spp., five (5.5%) were FIV- positive and one (1.1%) was FeLV-positive. Co-infection with L. infantum and at least one other infectious agent was found in 9/50 (18.0%; CI: 8.6-31.4%) cats. In Group 1 (cats infected naturally by L. infantum), 4/50 (8.0%) cats were positive for FIV, 4/50 (8%) for Mycoplasma spp. and 1/50 (2.0%) was co-infected with FeLV and Mycoplasma spp. In Group 2 (cats non-infected with L. infantum), 2/40 (5.0%) cats were infected with Mycoplasma spp. and 1/40 (2.5%) was co-infected with FIV and Mycoplasma spp. All cats were negative for Ehrlichia spp., Babesia spp. and Anaplasma platys. CONCLUSION: A low prevalence of co-infection in Leishmania-infected and non-infected cats was found. Co-infections with Leishmania and vector-borne diseases in cats are not common in this area endemic for VL in Brazil.