I haven't seen the research, but neither of these are primarily anti-viral so I'd doubt they would work. I repeat, I haven't seen the research. But when I was in the natural medicine biz managing health food stores, my training from herbalists, nor the herbals I've owned, did not use either of these as anti-virals. Astragalus is primarily used for boosting the immune system and Pao D'Arco as an anti-fungal, particularly against candida albicans. There are many herbs which have been used primarily as anti-virals, including St. John's Wort, ofive leaf, elderberry, and others. Two that have been used explicitly for herpes are the amino acid L-lysine and the herb melissa (or lemon balm). Herb Pharm had an anti-viral formula for latent and chronic viruses including herpes with the two main herbs being lomatium (usually thought of as a liver cleanser) and hypericum (St. John's Wort) plus other herbs. Good luck.
Right now I take the following once a day:
L-lysine 1000mg
Vitamin D3 2000IU
Zinc 50mg
Bee Propolis 1000mg
Astragalus Root 1500mg
I did read on St. John's Wort, but it seems to be more a mood stabilizer and can not be taken since it would interact with my Citalopram. I am still reading on Elderberry.