Final answer:
The determination of bacteriophage titer through plaque assays allows scientists to quantify virus particles and assess the neutralizing capacity of antibodies. This process is crucial for diagnosing viral infections, confirming bacterial presence, and genetic research.
Step-by-step explanation:
The determination of a bacteriophage titer involves calculating the concentration of virus particles in a sample through the use of a plaque assay. This method is essential for understanding the viral load and the efficacy of neutralizing antibodies against viruses. The titer is determined from the reciprocal of the highest dilution that shows a 50% reduction in plaques on a bacterial lawn. For example, if the highest dilution showing 50% reduction is 1/64, the titer would be expressed as 64. During this process, a clear area, known as a plaque, forms where the bacteriophages lyse the host bacterial cells. Each plaque represents a single virus that has infected and replicated within bacteria, destroying the cells and thereby creating the clearing. By counting the plaques, scientists can determine the viral titer using the original undiluted lysate volume.
Application in Viral Infection Diagnosis and Genomic Library Screening
The plaque assay is not only used to measure virus concentration but also to diagnose viral infections by assessing the immune response, such as in plaque reduction assays or neutralization assays using patient serum. Moreover, it is crucial in bacteriophage lysis confirmation methods for bacteria identification such as Y. pestis. Furthermore, this method is applied in screening genomic libraries to find genes of interest or to titrate recombinant phage clones in genetic research. By culturing host cells and using serial dilutions, scientists are able to count the plaques and interpret the viral load.