Monophyletic origins of the metazoa: an evolutionary link with fungi.

A phylogenetic framework inferred from comparisons of small subunit ribosomal RNA sequences describes the evolutionary origin and early branching patterns of the kingdom Animalia. Maximum likelihood analyses show the animal lineage is monophyletic and includes choanoflagellates. Within the metazoan assemblage, the divergence of sponges is followed by the Ctenophora, the Cnidaria plus the placozoan Trichoplax adhaerens, and finally by an unresolved polychotomy of bilateral animal phyla. From these data, it was inferred that animals and fungi share a unique evolutionary history and that their last common ancestor was a flagellated protist similar to extant choanoflagellates.

Effects of chicken embryo age on time to death following infection by avian influenza viruses: implications for distinguishing highly pathogenic isolates.

When white leghorn (WL) chick embryos ranging in age from 8 to 13 days were inoculated with a variety of avian influenza virus (AIV) isolates, strain-specific differences in embryo mean death times (MDT) were observed. Non-highly pathogenic (nHP) strains killed 8 or 9 day-old embryos much more rapidly than 12 or 13 day-old embryos. Highly pathogenic (HP) strains, however, were less sensitive to embryo age resulting in similar MDTs in both older and younger embryos. These observations were consistent over a broad range of virus doses for both HP and nHP strains. When a HP derivative of H5N2 AIV was compared to its nHP parent, the derivative killed older embryos more rapidly than the parent virus, while MDTs in younger embryos were the same for both parent and derivative. The two strains further exhibited clear differences in the structure of their respective hemagglutinin, a previously described pathogenicity determinant for this virus. Thus it may be possible to readily demonstrate the HP phenotype in AIV strains based on MDT measurements in WL embryos.

Characterization of infectious bronchitis virus using monoclonal antibodies.

Three monoclonal antibodies (MABs) reactive against two structural proteins--the nucleoprotein (NP) or the surface (S) protein--of avian infectious bronchitis virus (IBV) were produced and characterized. The MABs did not neutralize virus infectivity or inhibit hemagglutination. Their reactivity patterns with the homologous strain and eight heterologous strains of IBV were determined using the indirect immunoperoxidase test, the indirect immunofluorescent test, transfer-immunoblotting of separated proteins, and a dot-immunoblotting assay (DIA). Two MABs, NP- or S-protein-specific, reacted with all nine strains; one (NP-specific) reacted with only two strains. The two MABs reacting with all nine strains of IBV also detected 18 IBV field isolates of unknown serotype in the DIA. The MAB detecting only two strains did not react in the DIA. The diagnostic application of these MABs appears promising.

Serological evaluation of some psittaciformes for budgerigar fledgling disease virus.

Breeding psittaciform birds (psittacines) from three geographically separated aviaries experiencing fledgling mortality were monitored during 1983 and 1984 for specific serum antibody to budgerigar fledgling disease virus (BFDV) using a fluorescent-antibody virus-neutralization test. Neither the time nor the extent of exposure to the virus was known. Serological titers were positive in 45% of birds sampled from Aviary 1, 25% from Aviary 2, and 11% from Aviary 3. Several species of psittacine birds within each aviary were serologically positive for BFDV. The results indicated that a papovavirus similar to BFDV appears to infect a wide range of captive adult psittacine birds. Macaws (Ara sp. and Anodorhynchus sp.) were evaluated for distribution of infection. Each species within these two genera showed positive serological titers to BFDV. Three groups of birds showed a decrease in serum antibody titer to BFDV at 1 and 2.5 months after the first sampling. Positive titers decreased from 66 to 20% for one group and from 60 to 50% for a second group in 1 month, and they decreased from 42 to 17% for a third group in 2.5 months.

Amantadine resistance among hemagglutinin subtype 5 strains of avian influenza virus.

Several avian influenza virus strains of hemagglutinin subtype 5 were assayed for sensitivity to the antiviral drug amantadine. Most strains exhibited little sensitivity to the drug as measured by plaque reduction. The A/Chicken/Scotland/59 (CS59), however, was highly sensitive, making it easily distinguishable from the other H5 strains. Drug sensitivity of the viruses was also assayed in chicken embryos. The in ovo patterns of amantadine sensitivity differed from those detected in cell culture. The CS59 isolate could not be distinguished from all the other strains on the basis of its response to amantadine in ovo. Although amantadine protected chickens inoculated with CS59 from morbidity and mortality, drug-resistant viruses were readily isolated from the infected birds. As found with other amantadine-resistant variants, the structure of the matrix gene was altered in the resistant isolates. These results demonstrate that amantadine resistance is widespread among avian influenza viruses of the H5 subtype, that drug sensitivity in cell culture does not necessarily reflect responses to amantadine in ovo and in vivo, and, as previously found, amantadine-resistant derivatives of H5 strains may be isolated from birds protected by the drug.