What would be more effective for helping an epidemiologist determine that the infectious disease was viral instead of bacterial?
A) Hybridize the infectious agent with radiolabeled probes specific for the genes encoding viral caspids; only viral genes would hybridize.
B) Analyze a patient's serum in spectrophotometer to measure absorption wavelength; the photosynthetic pigments found in all bacteria would distinguish them from viruses, which lack such pigments.
Why and why not the other choice?
The answer is A, because all viruses have a caspid (protein coat). All viruses are closely related, so there will be homology in viral genes coding for the protein coats of different viruses.
B doesn't work because though there are no photosynthetic viruses, not all bacteria are photosynthetic (only cyanobacteria) and they are not infectious in humans.