Plant virus vectors-based expression systems have been widely studied for their development as antigen presentation systems as well as for the production of pharmaceutically important peptides. The CGMMV has been previously shown to be suitable for expression of foreign peptide [7] . In this study, CGMMV vector was used to express a 45 amino acid EB4 gene. The integration of the EB4 gene into the end of CGMMV coat protein gene was done via a leaky UAG read-through sequence. Transcripts generated from chimeric clones of pRT and pRG carrying CAA-UAG-CAA-UUA read-through codon sequences were not infectious. This is possibly caused by the failure of self assembly [16] , and thus none of the inoculated plants was systemically infected. The assembly of CGMMV into virus particle has been shown to be essential for the viral movement through phloem [17] , hence another chimeric clone pCG+FSRTRE was constructed carrying read-through sequence (AAA-UAG-CAA-UUA) from the wild-type CGMMV genome. The clone containing this read-through signal was infectious and produced chimeric CGMMV (Table 1 and Figures 4 and 5) . It is, thus, postulated that there is a read-through signal preference between different species of tobamoviruses, in this case between TMV and CGMMV causing possibly viral particle assembly failure. It has also been shown that KGMMV, the tobamovirus, which has the closest genome similarity to CGMMV [13] also utilizes the same CGMMV read-through signal reaffirming the differences between the tobamoviruses. Additionally, unlike other plant virus vectors [15, 18] , this study reaffirms that with CGMMV pI deviation did not appear to be a factor affecting infectivity [7] .