Biochemical comparison of seven commercially available prothrombin complex concentrates.

AIMS: A number of prothrombin complex concentrates (PCCs) are commercially available but they differ in terms of composition. We performed a series of studies to compare the biochemical properties of seven PCCs. METHODS: The following products were investigated: Beriplex P/N, Octaplex, S-TIM 4, PPSB Solvent Detergent, Uman Complex DI, Kaskadil and Cofact. Assays were performed to investigate levels of coagulation factors and their inhibitors, activated coagulation factors and heparin. The thrombin inhibitory capacity of each PCC was determined. Protein content was assessed using the Lowry method and sodium dodecyl sulphate-polyacrylamide gel electrophoresis. RESULTS: The data indicated little difference between most of the products in their levels of factors II, VII, IX and X, with the exception of Uman Complex which had no detectable factor VII. In all cases, the measured levels of coagulation factors were broadly similar to those labelled. Beriplex P/N showed the greatest capacity for thrombin inhibition, a reflection of the observed high levels of the coagulation inhibitors protein C, protein S, protein Z, and small amounts of antithrombin III and heparin in this product. All of the PCCs tested were negative for activated coagulation factors. Purity (i.e. therapeutic protein as a percentage of total protein) was highest in Beriplex P/N, and the second purest product was Uman Complex. CONCLUSION: This in vitro study showed considerable differences between PCCs in terms of coagulation inhibitory capacity and purity.

Inhibition of infectious human immunodeficiency virus type 1 particle formation by Gag protein-derived peptides.

Sequential overlapping Gag protein-derived oligopeptides of human immunodeficiency virus type 1 (HIV-1) 22 to 24 amino acids long, were synthesized and tested in vitro for antiviral activity. Two synthetic peptides, one derived from the matrix protein p17 (NPGLLETSEGCRQ, amino acids 47 to 59) and one located in the capsid protein p24 (PAATLEEMMTA, amino acids 339 to 349) inhibited the production of infectious virus when added to HIV-1-infected cultures when used in the range of 20 to 200 micrograms/ml. As shown by thin section electron microscopy, peptide treatment resulted in the release of immature, deformed virus particles suggesting that the two peptides interfered with assembly and maturation. Other Gag protein-derived oligopeptides had little or no influence on virus production. To characterize further the functionally active regions we synthesized peptide derivatives with three consecutive amino acids substituted by alanine; they did not cause inhibition. Therefore the regions responsible for inhibition were located between amino acids 50 to 61 in p17, and 342 to 350 in p24. These observations might lead to the development of a new antiviral strategy affecting the late stage of virus replication.

Inhibition of viral replication by monoclonal antibodies directed against human immunodeficiency virus gp120.

Monoclonal antibodies (MAbs) were raised against the glycoprotein gp120 of human immunodeficiency virus type 1 (strain HTLV-IIIB). The reactivity of five selected MAbs was characterized in several tests: ELISA, immunostaining of Western blots, immunofluorescence, immunoprecipitation, immunoelectron microscopy, alkaline phosphatase-anti-alkaline phosphatase assay and neutralization. The binding region was delimited by sequential overlapping Escherichia coli fusion proteins of the gp120 sequence between amino acids (aa) 49 and 280. In the ELISA, when using sequential overlapping 15 aa peptides, the binding epitopes were localized between aa 64 and 78 for three MAbs and between aa 114 and 123 for the fourth Mab. The fifth Mab showed multiple reactions with different peptides possibly indicating a reaction with a discontinuous epitope. In virus growth inhibition assays, all five MAbs inhibited the spread of HIV-1 infection in cell cultures after a single or repeated treatment at a concentration of 63 micrograms/ml of the purified MAbs. All MAbs showed low but significant neutralizing activity at concentrations of 100 micrograms/ml.