Abstract: Nucleic acid sandwich hybridization assays are provided that incorporate one or a combination of background reduction steps. Those steps include use of a separate capture probe and separation from immobilized capture probes by cleavage and isolation. A very sensitive assay for RNA targets includes both of those steps, plus RNA binary probes, an RNA-directed RNA ligase and amplification by an RNA-directed RNA polymerase. Kits of reagents for performing assays according to this invention are also provided.

Abstract: There are provided nucleic acid hybridization assays for RNA targets using RNA binary probes and a ribozyme ligase that is a stringent RNA-directed RNA ligase. Preferred assays include exponential amplification for signal generation. Tetrahymena ribozyme ligase is a preferred ligase for use in this invention. It may be tethered to hold it close to the ligation junction. One assay according to this invention is a "tethered ligase chain reaction." Also provided are kits for performing assays according to the invention.

Abstract: A method and preparation for the storage and delivery of purified reagents is disclosed. In one aspect, the preparation comprises an amount of a first wax carrier, the first wax carrier having a first melting point, and an amount of a first reagent, wherein first reagent is a substantially purified preparation of at least one biological or chemical reagent. The first wax carrier and the first reagent are combined to form a solid first reagent portion. The solid mixture is combined with a second reagent portion comprised of at least one biological or chemical reagent in an inactive form.