Thank you. The example makes it much clearer.
It appears as if this is from a textbook. Textbooks need to be transcribed according to the guidelines in Braille Formats: Principles of Print to Braille Transcription 1997 with BANAs 2007 Updates.
I can answer this for you, but for future reference questions regarding textbook material should be posted in the Braille Formats/Textbook Forum.
Your example pertains to spelling. Letter indicators are definitely required before each letter. It does not matter if the letter is followed by punctuation or not.