Molecular characterisation of the 3'-end of the astrovirus genome.

We have sequenced the 3'-end of the RNA genomes of 14 serotyped and 12 untyped isolates of human astrovirus. The sequences, which include all 8 serotypes, were used to predict secondary structures, postulate possible functional domains, reveal conserved regions suitable for nucleic acid amplification and perform phylogenetic analysis. The final nucleotides of the capsid protein precursor gene and the adjacent 3'-noncoding region were highly conserved and, except for 35 nucleotides with homology to a sequence in the 3'-end of a coronavirus RNA genome, unique to astrovirus family.

Detection of all serotypes of human astrovirus by the polymerase chain reaction.

A reverse transcription (RT) and polymerase chain reaction (PCR) was designed for the detection of astroviruses based on a conserved nucleotide sequence in the 3'-end of the genome of the 7 known serotypes of human astrovirus. Thirty-eight samples found to contain astrovirus by electron microscopy (EM) were used for evaluation of the assay. The samples were dialyzed for 1 h to remove potential low molecular weight inhibitors of the RT-PCR.

Detection of hepatitis A virus in clinical and environmental samples by immunomagnetic separation and PCR.

Magnetic beads coated with antibodies against surface epitopes of the hepatitis A virus (HAV) captured efficiently viral particles from various types of samples. Contaminating substances, including particulate material, were removed by using a magnet to retain the beads during the washing procedure. A sensitive reverse transcriptase/nested polymerase chain reaction (RT-PCR) was developed to confirm the presence of viral particles on the beads.