What type of primers only amplifies RNA with a specific sequence during RT-PCR?

In the context of RT-PCR (Reverse Transcription Polymerase Chain Reaction), target-specific primers are crucial for amplifying a specific RNA sequence. These primers are designed to be complementary to a unique region of the RNA of interest, ensuring that only that particular RNA sequence is targeted and amplified during the reaction.

Using target-specific primers allows researchers to focus on amplifying the specific RNA they want to study, which is essential for applications like gene expression analysis, where distinguishing between different RNA transcripts is necessary. This specificity minimizes the risk of amplifying non-target sequences, thereby enhancing the accuracy and reliability of the results.

The other primer types mentioned have distinct roles. Random hexamers can initiate synthesis from various regions of RNA, which may lead to non-specific amplification. Oligo dT primers are designed to bind to the poly(A) tails of mRNA, useful for targeting mRNA in general but not specific to any particular sequence. Universal primers would theoretically amplify a broad range of sequences, thus lacking the specificity needed for targeted studies. Therefore, target-specific primers are the most appropriate choice for amplifying RNA with a defined sequence in RT-PCR.