  Galaxies have different morphology, gas content and star formation rate (SFR)
in dense environments like galaxy clusters. The impact of environmental density
extends to several virial radii, and galaxies are pre-processed in filaments
and groups, before falling into the cluster. Our goal is to quantify this
pre-processing, in terms of gas content and SFR, as a function of density in
cosmic filaments. We have observed the two first CO transitions in 163 galaxies
with the IRAM-30m telescope, and added 82 more measurements from the
literature, for a sample of 245 galaxies in the filaments around Virgo. We
gathered HI-21cm measurements from the literature, and observed 69 galaxies
with the Nan\c{c}ay telescope, to complete our sample. We compare our filament
galaxies with comparable samples from the Virgo cluster and with the isolated
galaxies of the AMIGA sample. We find a progression from field galaxies to
filament and cluster ones for decreasing SFR, increasing fraction of galaxies
in the quenching phase, increasing proportion of early-type galaxies and
decreasing gas content. Galaxies in the quenching phase, defined as having SFR
below 1/3 of the main sequence rate, are only between 0-20\% in the isolated
sample, while they are 20-60\% in the filaments and 30-80\% in the Virgo
cluster. Processes that lead to star formation quenching are already at play in
filaments. They depend mostly on the local galaxy density, while the distance
to the filament spine is a secondary parameter. While the HI to stellar mass
ratio decreases with local density by ~1 dex in the filaments, and ~2 dex in
Virgo with respect to the field, the decrease is much less for the H$_2$ to
stellar mass ratio. As the environmental density increases, the gas depletion
time decreases, since the gas content decreases faster than the SFR. This
suggests that gas depletion significantly precedes star formation quenching.
