A researcher identifies a gene in Streptococcus pyogenes that is suspected to encode a toxin. The gene is present in strains that cause disease but absent in closely related non-pathogenic strains. The researcher deletes the gene from the bacterial genome and finds that the mutant strain no longer causes disease in mice. Which of Falkow’s molecular postulates has the researcher fulfilled? (select all that apply)

Question

A researcher identifies a gene in  Streptococcus pyogenes  that is suspected to encode a toxin. The gene is present in strains that cause disease but absent in closely related non-pathogenic strains. The researcher deletes the gene from the bacterial genome and finds that the mutant strain no longer causes disease in mice. Which of Falkow’s molecular postulates has the researcher fulfilled? (select all that apply)

Answer

Specific inactivation of the gene associated with the suspected virulence trait should lead to a measurable loss in pathogenicity or virulence

Answer

Reversion or allelic replacement of the mutated gene should lead to restoration of pathogenicity

Answer

The phenotype or property under investigation is associated with pathogenic members of a genus or pathogenic strains of a species

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A researcher identifies a gene in Streptococcus pyogenes that is suspected to ...

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