Dear Mr. B:

You wrote:

Hope all is well with you. Although it is seldom a serious problem for native English speakers, deciding whether to use a gerund or an infinitive after a verb can be perplexing among students for whom English is a second language. For example,  I received a revision from the reviewer of  who have put a comment on title of a paragraph in my article as following: Please change “Semi-nested PCR for detection of T. gondii B1 gene” to “Semi-nested PCR to detect T. gondii B1 gene.” Would you please help me out with this problem?

These two phrases mean the same thing. This is a question of style. Using a verb is more direct and generally clearer.