SUMMARYN-methyl and N-ethyl isatin beta-thiosemicarbazones inactivate cell-free Parana and Pichinde viruses as well as three strains of lymphocytic choriomeningitis virus. This antiviral activity is abolished in the presence of the chelating agent EDTA. The rate of virus inactivation by N-methyl isatin beta-thiosemicarbazone is greatly enhanced and contlolled by the addition of cupric sulphate. Divalent cations of other first transition series metals are less effective. A difference exists in the copper requirement for fast inactivation of the prototype arenavirus (lymphocytic choriomeningitis) and the Tacaribe Complex of viruses (Parana and Pichinde). In the presence of 20/zi-N-methyl isatin beta-thiosemicarbazone, LCM and Pichinde viruses can be inactivated at about the same rate if 2o/zi-CuSO4 is added to the former and 16o #M-CuSO4 is added to the latter. Using 20/zM-N-methyl isatin beta-thiosemicarbazone and CuSO4 the inactivation of LCM is reduced, but not eliminated, in the presence of an equal amount of infectious Pichinde virus. Crude and highly purified Pichinde virus are inactivated at the same rate when exposed to identical concentrations of N-methyl isatin beta-thiosemicarbazone and cupric sulphate. There is little detectable change in inactivation rates when Pichinde or LCM viruses are grown in a variety of different cell lines.

Canine distemper is uncommon in the pet trade in the United States, in large part due to effective vaccines against Canine distemper virus (CDV). This is a report of CDV affecting 24 young dogs of multiple breeds shortly after sale by 2 pet stores in Wyoming during August–October 2010. Cases were diagnosed over 37 days. Diagnosis was established by a combination of fluorescent antibody staining, reverse transcription polymerase chain reaction, negative stain electron microscopy, and necropsy with histopathology. Viral hemagglutinin gene sequences were analyzed from 2 affected dogs and were identical (GenBank accession no. JF283477). Sequences were distinct from those in a contemporaneous unrelated case of CDV in a Wyoming dog (JF283476) that had no contact with the pet store dogs. The breeding property from which the puppies originated was quarantined by the Kansas Animal Health Department. Puppies intended for sale were tested for CDV. Canine distemper was diagnosed on site in November 2010. At that point 1,466 dogs were euthanized to eliminate dispersal of the disease through commercial channels. The investigation underscores the risks inherent in large-scale dog breeding when vaccination and biosecurity practices are suboptimal.