Answer the Following question

Question
1. The replicative cycle of sindbis and VSV takes only 6-8 hours. If a low MOI is used, at what time after infection would you expect the highest virus titer to be found? Explain.

2. Sequence analysis has revealed that large and small plaque variants of Sindbis exhibit slight differences in the sequence of their envelope glycoproteins. charged amino acids were present in exposed regions of the glycoproteins from the small plaque variants, but not the large plaque variants. Suggest a possible mechanism that may account for this variability in plaque size and explain briefly.

3. Why is it advantageous to use cells from different species when propagating and titrating animal viruses?