Deborah A. Eppstein

Alkaline protease associated with the matrix protein of a virus infecting the cabbage looper.

An alkaline protease was found to be tightly associated with the matrix protein of a nuclear-polyhedrosis virus infecting Trichoplusia ni . Partial purification of the protease was achieved by CaCl 2 precipitation of the matrix protein. The protease had a pH optimum of 9.5 using casein as substrate and behaved as a serine protease. It hydrolyzed N-benzoyl- l -tyrosine ethyl ester, and it was inhibited by Hg 2+ and Cu 2+ . Most of the protease was separated from the matrix protein by polyacrylamide gel electrophoresis at pH 9.5.

Degradation of matrix protein from a nuclear-polyhedrosis virus of Trichoplusia ni by an endogenous protease

Abstract The intact matrix protein of a nuclear-polyhedrosis virus of Trichoplusia ni could be isolated when a contaminating endogenous protease was inhibited by Hg 2+ . The subunit molecular weight of the intact matrix protein was approximately 28,000. When the protease was not inhibited, the matrix protein was degraded to a mixture of peptides which had a strong tendency to self-associate. The protease-degraded matrix protein preparation could be dissociated by 1.0 M formic acid into a single peptide and a peptide aggregate. The sum of the amino acid compositions of the peptide and peptide aggregate was identical, within experimental error, with the amino acid composition of the intact matrix protein.

Potent synergistic inhibition of herpes simplex virus-2 by 9-[(1, 3-dihydroxy-2-propoxy) methyl]guanine in combination with recombinant interferons

DHPG, an acyclic guanine nucleoside with the structure 9-[(1,3-dihydroxy-2-propoxy)methyl]guanine], showed potent synergism with recombinant alpha or beta interferons and modest synergism with gamma interferon in inhibiting the replication of herpes simplex virus type 2 in vitro. The most potent direct anti-herpes viral synergism was obtained by combination of DHPG and recombinant human interferon-beta-ser17; when combined, doses of each near their separate effective dose50s resulted in almost complete elimination of production of infectious virus within a single viral replication cycle. The anti-herpes viral activity of DHPG-interferon combinations was significantly greater than that obtained with acyclovir-interferon combinations.

Enhanced efficacy of the acyclic nucleoside 9-(1,3-dihydroxy-2-propoxymethyl)guanine in combination with gamma interferon against herpes simplex virus type 2 in mice

The acyclic nucleoside 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG) and recombinant mouse interferon gamma (rMuIFN-gamma) were evaluated for their efficacy alone and in combination against a herpes simplex virus type 2 systemic infection in mice. Intraperitoneally infected animals were treated once a day with the drugs at various concentrations for 5 days starting 24 h after inoculation. DHPG was given subcutaneously and rMuIFN-gamma intraperitoneally. For DHPG, the effective dose at which 50% of the mice survived (ED50 was lowered approximately 10-fold from 3.4 to 0.25 mg/kg when given in combination with an ineffective dose of 4MuIFN-gamma (10(3) units per mouse). For rMuIFN-gamma, the ED50 was lowered greater than 10-fold from 6 x 10(3) to less than 3 x 10(2) units per mouse when given in combination with a marginally effective dose of DHPG (1 mg/kg). Construction of an isobologram and calculation of the corresponding fractional protective dose index (less than 0.12 where values less than or equal to 0.5 are considered synergistic) indicates an enhanced protective interaction by the combination of the two drugs.

Controlled-Release and Localized Targeting of Interferons

Interferon’s (α and β), produced both by recombinant DNA technology as well as purified from natural sources, have been shown to be efficacious in treating certain cancers and viral diseases. Studies with γ-interferon have more recently been undertaken, and thus definition of their clinical utility is not yet as well defined. The treatment schedules usually involve multiple injections of the Interferon (IFN) over a period of several weeks to many months. Using such treatment regimens, the dose levels of the interferons needed to obtain efficacy can result in toxic side effects. For all these reasons, methods of increasing the ease of administration as well as the therapeutic ratio of interferons are warranted.

Therapeutic effects of a synthetic peptide of C-reactive protein in pre-clinical tumor models

Previous studies have shown that multilamellar vesicles (MLV) or other carriers containing purified human C-reactive protein (CRP) have therapeutic activity in preclinical tumor models. Here we evaluated the therapeutic effects of MLV containing novel synthetic peptides, derived from the structure of CRP, on the extent of (a) established lung metastases of fibrosarcoma T241 in C57B1/6 mice, (b) survival of C57B1/6 mice bearing established liver metastases of colon carcinoma MCA-38, and (c) primary tumor growth of Renca renal carcinoma in Balb/c mice. In all cases, a single synthetic CRP peptide, RS-83277, demonstrated significant antitumor effects comparable to that seen with intact CRP. Two other synthetic CRP peptides, RS-83287 and RS-83147, showed no therapeutic activity and were comparable to control MLV containing only buffer. None of the peptides contained sequences homologous with that of the phagocyte stimulant, tuftsin. Activity of MLV-encapsulated RS-83277 was dose-dependent, and a comparable dose of the soluble peptide, given either alone or following injection of buffer-MLV, was ineffective. These results demonstrate immunotherapeutic potential for a novel synthetic peptide derived from CRP, and endogenous acute-phase protein.