If a loan borrower has declared Chapter 13 bankruptcy, can loan officer from the bank respond to court pleadings, or do we need an attorney?

It would not be possible for the bank to file a petition in bankruptcy court without representation by an attorney. While an individual may represent himself or herself in court, a legal entity must be represented by an attorney. 705 ILCS 205/11. Attempting to represent a legal entity as an employee/agent would constitute the unauthorized practice of law. Housing Authority v. Tonsul, 115 Ill. App.3d 739, 740 (1st Dist. 1983).