In general, the second aashrama (namely grihasthaas) have the main responsibility of protecting dharma as they follow the jaImini mImaMsa sUtrAs, which begins with athAto-dharma-jiGYAsA followed by chodana-lakshaNaH-artho-dharmaH. This should be contrasted with the fourth aashrama, the sannyaasins, who have renounced everything for the sake of brahma-jiGYAsa, following the bAdarAyaNa sUtrAs, which begins with athato-brahma-jiGYAsA.
It is sad that in the current days, when virus  of conversion is spreading, the protection of dharma has fallen on the shoulders of sannyAsins. It is not that they are doing poor job out of it. In fact they are excelling in what they are doing. But it is a travesty that the current kaala (kali-kaala!!!) is of that nature that everyone else, other than the individuals belonging to the fourth aashrama, has turned into an artha kaami and kaama kaami leaving alone dharma.
 It should actually be fungus, rather than virus. virus has a raajasik nature, while fungus has a taamasik nature. People who convert others and people who are converted are full of taamasik nature.