López Santamarina, AroaLamas Freire, AlexandreMondragón Portocarrero, Alicia del CarmenCardelle Cobas, AlejandraRegal López, PatriciaRodríguez Ávila, José AntonioMiranda López, José ManuelFranco Abuín, Carlos ManuelCepeda Sáez, Alberto2021-01-142021-01-142021Lopez-Santamarina, A.; Lamas, A.; del Carmen Mondragón, A.; Cardelle-Cobas, A.; Regal, P.; Rodriguez-Avila, J.A.; Miranda, J.M.; Franco, C.M.; Cepeda, A. Probiotic Effects against Virus Infections: New Weapons for an Old War. Foods 2021, 10, 130http://hdl.handle.net/10347/24173This review aimed to gather the available literature investigating the effects of probiotics against the most common viral infections using in vitro trials in cell lines and in vivo clinical trials in both experimental animals and humans. Probiotics were employed to prevent and reduce symptoms of infections caused by common viruses, especially respiratory tract viruses, but also for viral digestive infections (such as rotavirus, coronavirus, or norovirus) and other viral infections (such as viruses that cause hepatitis, human papillomavirus, human immunodeficiency virus, and herpes simplex virus). Different probiotics have been studied to see their possible effect against the abovementioned viruses, among which different Lactobacillus species, Bifidobacterium, Clostridium, Enterococcus, and Streptococcus can be highlighted. In many cases, mixtures of various probiotic strains were used. Although the results obtained did not show similar results, in most cases, probiotic supplementation improved both barrier and biochemical immune responses, decreased susceptibility to viral infections, and enhanced the effects of concomitant vaccines. Works collected in this review show a beneficial effect of probiotics in the prevention and treatment of different viral infections. We found interesting results related to the prevention of viral infections, reduction of the duration of diseases, and decrease of symptomseng© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)Atribución 4.0 Internacionalhttp://creativecommons.org/licenses/by/4.0/ProbioticGut microbiotaViral infectionVirusesInfluenzajournal article10.3390/foods100101302304-8158open access