Antiviral properties of polysaccharides from Agaricus brasiliensis in the replication of bovine herpesvirus 1.

Natural products are an inexhaustible source of compounds with promising pharmacological activities, including antiviral action. In the present study, the antiviral potential of polysaccharide-peptide (PLS) and an extracted ß-glucan from Agaricus brasiliensis were investigated in the replication of bovine herpesvirus 1 (BoHV-1) in HEp-2 cell cultures. The cytotoxicity (CC50) was assayed by the MTT method and the antiviral activity (IC50) was estimated by the plaque reduction assay. To study the possible mode of action of PLS and ß-glucan, the following protocols were performed: the virucidal assay, adsorption assay and the time-of-addition assay. The PLS presented a selectivity index (SI) higher than 12.50 and ß-glucan 9.19. The antiviral inhibition (67.9%) in cells treated with PLS during virus infection was higher than that in cells treated prior to or post infection. The ß-glucan presented high inhibition of virus replication by plaque assay (83.2%) and by immunofluorescence assay (63.8%). Although the mechanism has yet to be defined, we suggest that PLS and ß-glucan inhibited BoHV-1 replication by interfering with the early events of viral penetration. Additional studies are required for a better understanding of the mechanism of action of PLS and ß-glucan.

Antiviral activity of aqueous and ethanol extracts and of an isolated polysaccharide from Agaricus brasiliensis against poliovirus type 1.

AIMS: Agaricus brasiliensis (previously named Agaricus blazei ss. Heinem), also known as the sun mushroom is native of Southeast Brazil, and is widely consumed, mainly in the form of tea, due to its nutritional and pharmacological properties. In this study, we tested aqueous (AqE) and ethanol (EtOHE) extracts and an isolated polysaccharide (PLS) from the fruiting body of A. brasiliensis, for antiviral activity against poliovirus type 1 in HEp-2 cells. METHODS AND RESULTS: The evaluation of the time of addition by plaque assay showed that when AqE, PLS and EtOHE were added, just after the virus inoculation (time 0 h), there was a concentration-dependent reduction in the number of plaques up to 50%, 67% and 88%, respectively, with a selectivity index (SI) of 5.4, 9.9 and 12.3, respectively. CONCLUSIONS: The test substances showed antiviral activity and were more effective when added during the poliovirus infection. As they had little effect on reducing viral adsorption and did not show any virucidal effect, we suggest that they act at the initial stage of the replication of poliovirus. SIGNIFICANCE AND IMPACT OF THE STUDY: These results corroborate that basidiomycetes can be a rich source of potential antiviral compounds.

N-terminal amino acid sequences of the major outer membrane proteins from a Neisseria meningitidis group B strain isolated in Brazil.

The four dominant outer membrane proteins (46, 38, 33 and 28 kDa) were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in a semi-purified preparation of vesicle membranes of a Neisseria meningitidis (N44/89, B:4:P1.15:P5.5,7) strain isolated in Brazil. The N-terminal amino acid sequence for the 46 kDa and 28 kDa proteins matched that reported by others for class 1 and 5 proteins respectively, whereas the sequence (25 amino acids) for the 38 kDa (class 3) protein was similar to class 1 meningococcal proteins. The sequence for the 33 kDa (class 4) was unique and not homologous to any known protein.

Study on thermostabilizers for trivalent oral poliomyelitis vaccine

Different formulations of trivalent oral poliomyelitis vaccine were tested, in order to obtain better thermostability, reduce corrosion of machinery and improve production costs. Magnesium chloride, sucrose, arginine and 199-Hank's medium were used in the formulations. The most appropriate formulation was a mixture of MgCl2 and arginine, which was highly thermostable, and had low production costs. The low corrosive formulation was rejected, due to low thermostability on storage

Study on thermostabilizers for trivalent oral poliomyelitis vaccine.

Different formulations of Trivalent Oral Poliomyelitis Vaccine were tested, in order to obtain better thermostability, reduce corrosion of machinery and improve production costs. Magnesium chloride, sucrose, arginine and 199-Hank's medium were used in the formulations. The most appropriate formulation was a mixture of MgCl2 and arginine, which was highly thermostable, and had low production costs.