The invention provides compounds having immune-modulating and/or anti-inflammatory and/or anti-viral activity, wherein compounds of the invention include peptides and peptidomimetics. The invention further provides methods of using immune-modulating and/or anti-inflammatory and/or anti-viral compounds of the invention. In particular, the invention provides methods for treating a disease related to an immune disorder or inflammation or viral infection by administering an amount of a G2-checkpoint-abrogating peptide or peptidomimetic sufficient to inhibit the disease.