If the applicant is a company (juristic entity), then it may only use a patent practitioner to prosecute the patent application in the US. If the applicant is an individual or group of individuals, then one of the inventors may prosecute the application pro se. A patent practitioner is an attorney or agent who have been admitted to practice before the US Patent Office. This requires having the necessary technical background and passing the Patent Bar. So the answer to your question is that unless the employee has been admitted to practice before the US Patent Office, they may not prosecute the patent application.
37 CFR 1.31 Applicant may be represented by one or more patent practitioners or joint inventors.
An applicant for patent may file and prosecute the applicant's own case, or the applicant may give power of attorney so as to be represented by one or more patent practitioners or joint inventors, except that a juristic entity (e.g., organizational assignee) must be represented by a patent practitioner even if the juristic entity is the applicant. The Office cannot aid in the selection of a patent practitioner. An applicant who is a juristic entity must be represented by a patent practitioner. An applicant for patent, other than a juristic entity (e.g., organizational assignee), may file and prosecute his or her own application, and thus act as his or her own representative (pro se) before the Office.