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A polymerase chain reaction (PCR) and dot blot hybridization (DBH) test have been developed for the diagnosis of infection by a novel circovirus of geese (GoCV). These tests were applied to samples of bursae of Fabricius from sick and dead birds from commercial goose farms in Hungary. In this second report of the occurrence of circovirus infection in diseased geese, 103 of 214 (48.1%) and 37 of 150 (24.6%) birds, and 49 of 76 (64.5%) and 18 of 76 (23.7%) flocks were positive by PCR and DBH respectively. The sensitivity of the PCR test was such that 0.10 fg of virus DNA was detectable. The DBH test was less sensitive, only detecting larger amounts (40 pg) of DNA, but was used as a semi-quantitative method for detecting the presence of virus. The incidence of infection was affected by factors such as the age of the birds and rearing methods.

Circovirus-like, spherical particles measuring 16 to 18 nm in diameter were detected in organ homogenates from adult canaries that had died after a short illness characterized by dullness, anorexia, lethargy and feather disorder. A polymerase chain reaction method, based on degenerate primers specific to conserved amino acid sequences in the circovirus replication-associated protein, was used to amplify DNA specific to a novel circovirus, tentatively named canary circovirus (CCV). Sequence analysis of a 510 nucleotide genomic fragment indicated that CCV exhibited 67.4, 64.9, 53.7 and 53.9% nucleotide identities and 70.0, 61.8, 40.4 and 40.1% amino acid identities with columbid (pigeon) circovirus (CoCV), beak and feather disease virus (BFDV), porcine circovirus type 1 and porcine circovirus type 2, respectively. CCV therefore represents a new avian virus of the genus Circovirus of the family Circoviridae, and is more closely related to CoCV than BFDV.The availability of nucleotide sequence data will facilitate the development of DNA-detecting diagnostics with which the prevalence of CCV infections can be assessed.

The Cux-1 isolate of chicken anaemia virus (CAV) was passaged over 320 times in Marek's disease virus transformed chicken lymphoblastoid (MDCC-MSB1) cells. Comparison of the infectivity titres of virus pools derived from viruses that had received 0 (P0), 49 (P49), 170 (P170) and 320 (P320) passages in our laboratory indicated that the yields of infectious virus increased over 100-fold with passage number from P0 to P170. P320 exhibited unusual cell culture growth characteristics in that, unlike its lower passage counterparts, virus-specific immunofluorescence (IF) and cytopathic effect were detected at very low levels at 2 days post infection, with an additional passage of infected cells into fresh medium being required to produce high levels of infectious virus. Experimental infection of 1-day-old SPF chicks showed that P170 and P320 were substantially attenuated compared to P49 and a pathogenic, low-passage isolate used as control. When assessed by the indirect IF test, infection of 1-day-old chicks with the P49 and P170 isolates elicited similar levels of CAV-specific antibody to those elicited by infection with the pathogenic, low-passage virus and higher than those elicited by infection with the P320 isolate. Experimental infection of 5-week-old chicks indicated that the attenuated P170 and P320 isolates invoked similar CAV-specific antibody levels to those invoked by the pathogenic P49 and control isolates.