Methods and compositions for diagnosing, preventing or treating a viral infection in a subject comprising administering to a subject in need thereof an effective amount of a glycosidase or a sulfatase to degrade a glycan, such as heparan sulfate, to inhibit viral infection, such as COVID-19. Methods for identifying a glycosidase, a sulfatase, or a microbe associated with increased susceptibility to viral infection in a subject.

The invention relates to the field of bioengineering. In particular, the invention relates to a heparinase-producing Pseudomonas stutzeri strain and a heparinase derived therefrom. Furthermore, the invention relates to the preparation and use of the heparinase.

The invention relates to the field of bioengineering. In particular, the invention relates to a heparinase-producing Pseudomonas stutzeri strain and a heparinase derived therefrom. Furthermore, the invention relates to the preparation and use of the heparinase.

Isolated and prepared heparinases SDhep I and SDhep II obtained from a bacterium Sphingobacterium daejeonense are heparin enzymes that have not been reported. The isolated and prepared enzymes were obtained by steps of bacterium fermentation, crude enzyme extraction, multi-step column chromatography and so on. A study in properties showed that the two enzymes are specific for enzymolysis of heparin and are expected to be used in low molecular weight heparins preparation or heparin quality testing.

Provided are a sulfated heparin oligosaccharide as well as a preparation method and an application thereof. The sulfated heparin oligosaccharide molecule contains an unsaturated double bond resulting from enzymolysis by heparinase at the non-reducing end thereof, an uronic acid derivative and a glycosylamine derivative; and has a structure represented by formula I, wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.a, R.sub.b, R.sub.c, R.sub.d; R.sub.x, R.sub.y, R.sub.z, and n are as defined herein. The preparation method obtains a sulfated oligosaccharide with a controllable degree of sulfation. The sulfated heparin oligosaccharide has a high activity for inhibiting heparanase in vitro, with an activity 4-5 times higher than that of heparin for inhibiting cell adhesion and migration, and an activity 2-3 times higher than that of heparin for resisting tumor metastasis in mice, thus having a relatively good effect in resisting tumor metastasis and a relatively high specificity.

Heparinases SDhep I and SDhep II obtained from a bacterium Sphingobacterium daejeonense are heparin enzymes that have not been reported. The enzymes were obtained by steps of bacterium fermentation, crude enzyme extraction, multi-step column chromatography and so on. A study in properties showed that the two enzymes are specific for enzymolysis of heparin and are expected to be used in low molecular weight heparins preparation or heparin quality testing.

The present invention relates to the use of agents (including heparin derivatives) for the prevention and/or treatment of CNS damage.