  The quintessence field coupled to the cosmic neutrino background (CNB) has
been widely discussed as an alternative mechanism to address the coincidence
problem. As it is well known, it is possible to extend such models to obtain
quintessential inflation, that is, to incorporate inflationary stage as well.
Taking an alternative route, one can start from the well established
inflationary models and obtain successful quintessence models at the expense of
coupling with the CNB. To Follow this route, we use a slightly reformulated
model addressed in PRD95, 123521 (2017). This particular model assumes
$\mathcal{Z}_2$ symmetry for both scalar field potential and coupling term,
which then breaks down in course of the cosmological evolution. For our
discussion, however, the $\mathcal{Z}_2$ symmetry of the potential is not
mandatory the model to work. The conventional mechanism of particle production
by the oscillating inflaton field (and their subsequent thermalization) remains
operative. It is plain to see that the proposed construction can be easily
applied for many successful models of inflation to incorporate dark energy at
the expense of coupling with the CNB. We address the issue of neutrino nuggets
from the quantum field theory point of view. Namely, these nuggets are
considered as bound states caused basically by the Yukawa force, which arises
in the framework of linear perturbation theory due to exchange of virtual
quanta of quintessence field between the neutrinos.
