Lysates from serial passages the CVB3 vectors were examined for stability of expression of the inserted HIV-1 protein coding regions. Diagrams show P1 region of coxsackievirus and, if applicable, where any deletions were found to occur during serial passage. Filled in arrowheads to right of gel signify expected size of proteins. If applicable, empty arrowheads indicate the majority deletion product. Data is representative of repeated experiments. (A) CVB-MA passages 6–10. The 17 kD matrix protein remained stable through the 10th passage. (B) Blot of passages 1–3 of CVB-CA construct lysates. First and second passage show expected 24 kD CA protein expression. By the third passage CA is deleted from virus. This experiment was repeated with identical results. (C) Early passage of CVB-MACA show expression of the 41 kD protein, but only truncated proteins are subsequently detected. (D) Serial passage of CVB-MANC 48 kD protein shows, similar to CVB-MACA, the HIV-1 sequence is truncated after the first passage.