The host glycosylation mechanism synthesizes the carbohydrates of glycoproteins of viral envelopes. Due to the loss of the Cytidine Monophospho-N-Acetylneuraminic Acid Hydroxylase gene by some mammalian species, including humans (negative-CMAH), Neu5Gc is no longer synthesized. Uptake of Neu5Gc by negative-CMAH species, through the intake of food products derived from positive-CMAH mammals, leads to incorporating Neu5Gc-glycans in the glycocalyx (xenosialylation). Neu5Gc, being a Mammalian-associated Carbohydrate Antigen (MCA), acts as a non-self-antigen, inducing an inflammatory reaction (Xenosialitis), and triggering the production of circulating antiNeu5Gc antibodies to attack/remove all incorporated Neu5Gc. In the state of Xenosialitis, the virus-neutralizing antibodies produced by a heavily xenosialylated patient following exposure to viral infection (including SarsCoV2) or anti SarsCoV2 vaccination cross-react against all incorporated non-self Neu5Gc-MCA glycans due to their resemblance with viral envelope antigens synthesized by the host glycosylation mechanism. In addition, the circulating anti-XeSias antibodies determine the massive removal of the circulating neutralizing FC-xeno-contaminated antibodies by the serum, living only the hyper-inflammatory agalattosylated antiviral IgG antibodies. Therefore, we hypothesize that the combination of antibody cross-reaction against non-self Neu5Gc-MCA glycans and the massive removal of the xeno-contaminated newly formed neutralizing antibodies in favor of hyper reactive antibodies, could be the cause of the massive inflammatory reaction (cytokine storm, coagulopathies, neuropathies) observed in Covid 19 patients or after anti-SarsCoV2 vaccination. This analysis is an invitation to investigate the post-infectious and/or post-vaccination adverse phenomena in the light of xenosialization as a key to understanding the severe post viral and post vaccine complications, including SARS-CoV2 infection or related vaccination.

Feline coronavirus (FeCoV) causes enteric disease in cat worldwide. In general, FeCoV infection is characterized by self- limiting gastroenteritis but not understood changes can give rise to mutants that lead to the development of feline infectious peritonitis (FIP). In cats, FeCoV replicates in the intestines and spreads by fecal-oral transmission and persists in multi-cats households by infec-tion and re-infection by the same or another viral strain. Although current evidence shows that probiotics have promise for enhancing health benefits protecting from viral infection, today there are no studies regarding the use of probiotics in reducing fecal emission of feline coronavirus in naturally infected cats. The aim of the present study was to evaluate the effect of specific mul-ti-strain probiotics on FeCoV viral load in 25 naturally-infected cats. The study population con-sisted of purebred Birmanian cats, of which 14 females and 11 males, aged from1 to 4 years, and positive for FeCov by Real-time PCR on fecal sample. Two microcaps of probiotic formulation containing billion bacteria were administered to all cat once a day for 60 consecutive days. After probiotic administration, clinical conditions and FeCov viral load was assessed by Real-time PCR on fecal samples. All animals did not present alteration in the clinical condition at T1 (after probiotic administration); seventeen out of 25 cats tested negative at the end of the study, while the remaining 8 cats tested positive at the end of the study. The results of the present study suggest that high concentrations of live probiotics supplementation are well-tolerated and may poten-tially reduce the fecal FeCoV viral load.