  We considered a {multi-block} molecular model of biological evolution, in
which fitness is a function of the mean types of alleles located at different
parts (blocks) of the genome. We formulated an infinite population model with
selection and mutation, and calculated the mean fitness. For the case of
recombination, we formulated a model with a multidimensional fitness landscape
(the dimension of the space is equal to the number of blocks) and derived a
theorem about the dynamics of initially narrow distribution. We also considered
the case of lethal mutations. We also formulated the finite population version
of the model in the case of lethal mutations. Our models, derived for the virus
evolution, are interesting also for the statistical mechanics and the
Hamilton-Jacobi equation as well.
