Therapeutic effect of Xanthohumol against highly pathogenic porcine reproductive and respiratory syndrome viruses.

The infection by porcine reproductive and respiratory syndrome virus (PRRSV) has a severe impact on the world swine industry. However, commercially available vaccines provide only incomplete protection against this disease. Thus, novel approaches to control PRRSV infection are essential for the robust and sustainable swine industry. In our previous study, Xanthohumol (Xn), a prenylated flavonoid extracted for hops (Humulus lupulus L), was screened from 386 natural products to inhibit PRRSV proliferation and alleviate oxidative stress induced by PRRSV via the Nrf2-HMOX1 axis in Marc-145 cells. In this study, we furtherly found that Xn could inhibit PRRSV different sub-genotype strains infection with a low IC50 value in porcine primary alveolar macrophages (PAMs). In addition, it caused decreased expression of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-α in PAMs infected with PRRSV or treated with lipopolysaccharide. Animal challenge experiments showed that Xn effectively alleviated clinical signs, lung pathology, and inflammatory responses in lung tissues of pigs induced by highly pathogenic PRRSV infection. The results demonstrate that Xn is a promising therapeutic agent to combat PRRSV infections.