We tested purified preparations of brain tissue from 39 patients with Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker syndrome, or kuru, and from 32 patients with a variety of nonspongiform degenerative diseases, with the use of Western blots against an antiserum to a similarly purified fraction made from scrapie-infected hamster brain. Positive reactions occurred in 81 percent of the 31 specimens from the patients with Creutzfeldt-Jakob disease (and in all of the 7 specimens that were stored frozen for less than one year), in 3 of the 4 specimens from the patients with kuru, in 3 of the 4 specimens from the patients with Gerstmann-Sträussler-Scheinker syndrome, and in none of the specimens from the patients with other neurologic degenerative disorders, including familial or sporadic Alzheimer's disease; dementia associated with myoclonus, motor neuron disease, or parkinsonism; and acquired-immunodeficiency-syndrome encephalopathy. Immunologic testing has thus begun to provide a useful and rapid adjunct to neuropathological examinations and animal-transmission experiments for the diagnosis of the spongiform encephalopathies.

Sera collected from 1,102 individuals in 14 populations of the southwestern Pacific between 1956 and 1979 were tested by ELISA for antibodies to human T-cell leukemia virus type I (HTLV-I). Selected sera were also tested by particle agglutination and immunoblotting. Six of the populations had prevalences of antibodies greater than 4%, two populations had prevalences greater than 15%. Six populations had antibody prevalences of 2% or less. Three populations from the coast and northern islands of New Guinea had high prevalences of antibodies, while three New Guinea highland groups had virtually none. One population from the Solomon Islands had a high prevalence, while two others had very low prevalences. Two populations from small remote islands in Vanuatu both had high prevalences. Pacific sera did not neutralize a standard strain of virus readily neutralized by Japanese, European, and American sera. We conclude that infections with HTLV-I, some acquired more than 20 years ago, are widespread throughout the southwestern Pacific, even in several very isolated populations, although others have been spared. Some strains of HTLV-I in populations of the Pacific may have substantially different envelope proteins from prototype strains of America, Europe, and Japan.

RNA sequences of five flaviviruses were detected by a modified polymerase chain reaction (PCR) that incorporated a reverse transcriptase and RNase inhibitor. Oligonucleotide primer pairs were synthesized to amplify sequences from St. Louis encephalitis (SLE), Japanese encephalitis (JBE), yellow fever (YF), dengue 2 (DEN-2), and dengue 4 (DEN-4) viruses. The amplified products were visualized as bands of appropriate size on ethidium bromide-stained agarose gels. The identity of these products was confirmed by restriction endonuclease cleavage to generate fragments of predicted lengths. The reverse-transcriptase PCR (RT-PCR) successfully amplified flavivirus sequences from cell cultures, frozen brain tissue, and formalin-fixed, paraffin-embedded brain tissue. The reactions were highly specific, and the method compared favorably to two conventional assays of viral infectivity. RT-PCR followed by PCR with nesting primers (N-PCR) was 1,000-fold more sensitive in detecting virus than classical infectivity titration by intracerebral inoculation of suckling mice and nearly 1,000-fold more sensitive than amplification of virus in cell culture followed by inoculation of mice.