Viral Plaque AssaySkin Diseases, ViralCat DiseasesVirus ReplicationHemolytic Plaque TechniqueCell LinePlaque, AtheroscleroticDental PlaqueVirus CultivationAntibody-Producing CellsCytopathogenic Effect, ViralRickettsia rickettsiiRickettsia prowazekiiRickettsiaPancreatinHaplorhiniCulture TechniquesIdoxuridineNeutral RedVirologyMethodsVero CellsMethylcellulosePokeweed MitogensRickettsia typhi