Question

1) How are River's postulates for viruses different than Koch's postulates for bacteria? (4 points) 2) For the following tests, indicate what the test is measuring or identifying: (7 points) a. Electron microscopy b. Immunofluorescence microscopy c. ELISA d. Hemagglutinin assays e. Culture f. PCR g. DNA microarray 3) A new disease is circulating among St. Cloud State University. The patient's symptoms are a high fever, runny nose, and cough. How would you use any of the diagnostic tests in Chapter 7 to identify the virus? Make sure to identify what type of patient sample you would use, and detail the path of the virus through your tests. (4 points)

Answer 1

River's postulates for viruses are different than Koch's postulates for bacteria as River's postulates are modification of koch's postulates. According to Koch,

• the isolated microorganisms from diseased host should be first grown in pure culture
• and then when introduced into a healthy organism, it should cause disease.

But this cant be true for the viruses as viruses requires host cells for growth and reproduction and hence cannot be grown in oure cultures. River modifies his postulates and stated that

• at the time of the disease viral agent must be found in the host's body fluidsor in the cells
• the viral agent obtained from the diseased host when introduced into the healthyhost must be

1. either produces specific disease in the healthy host
2. or induces the formation of antibodies specific to that agent thus giving the evidence of infection
3. or it can be both