Evaluation of anti-AIDS drugs in conventional mice implanted with a permeable membrane device containing human T cells infected with HIV.

We now report the confirmation of the work of Hollingshead et al. (1995) on development of a cell based hollow fiber (HF) system for evaluating potential anti-AIDS drugs in vivo using conventional mice rather than SCID mice. CD4 +, CEM-SS cells infected with HIV/1, strain RF, at a multiplicity of infection of 0.1 were placed into HFs. The fibers were implanted into the peritoneal cavity of outbred Swiss mice. Using this model, the antiviral activity of azidothymidine (AZT) at doses of approximately 150, 75 and 37.5 mg/kg/day was evaluated by administering AZT to the mice in drinking water. Upon fiber removal on day 6, AZT treatment was shown to significantly increase CEM cell viability over the untreated, virus control group and significantly reduced the levels of HIV p24 and HIV RT activity.

An ELISA system for evaluating antiretroviral activity against Rauscher murine leukemia virus.

A system for evaluating the activity of antiviral agents against Rauscher murine leukemia virus (R-MuLV) has been developed using an enzyme linked immunosorbent assay technique. The activity of various antiviral compounds demonstrated in this assay system has been compared to their activity in the UV-XC plaque reduction assay, which has been used historically for evaluating anti-R-MuLV compounds. The assay is based upon detection of R-MuLV encoded p30 protein production in virus infected murine cells. The assay reagents are readily available and the assay system is amenable to automated data collection systems. Cytotoxicity evaluations are conducted in parallel to the Rauscher MuLV ELISA assay in order to assess drug-induced reductions in cell viability. Cytotoxicity evaluations are important to interpretation of the ELISA results since reductions in cell viability reduce viral protein production which would indicate an antiviral drug effect. This system is less sensitive than the classical UV-XC plaque reduction assay; however, it does offer an alternative to the time-consuming and labor-intensive plaque assay.

Novel method for evaluating antiviral drugs against human cytomegalovirus in mice.

A virus-host cell system in which human cytomegalovirus-infected human cells are entrapped in agarose plugs has been developed. This model provides an inexpensive method for the in vivo evaluation (with outbred, immunocompetent mice) of antiviral drugs against human viruses such as cytomegalovirus that replicate primarily or only in human cells.

Evaluation of continuous cell lines in antiviral studies with murine cytomegalovirus.

Cell culture systems were developed for rapid antiviral drug screening, using murine cytomegalovirus (MCMV) as an alternative to the slower growing human CMV. Since previous assay methods with MCMV employed mouse embryo fibroblasts (MEF cells), which are labor intensive to prepare and die off after 3-4 passages from primary culture, identification of virus-susceptible continuous cell lines was desirable. Three cell lines were found useful for assaying MCMV: C127I, SC-1, and 3T3. The antiviral agents acyclovir, ganciclovir, 5-fluoroarabinofuranosylcytosine, and 2'-fluoro-2'-deoxy-5-iodoarabinofuranosylcytosine were evaluated in the 3 continuous cell lines and in MEF cells. The 50% virus- or cell-inhibitory concentration values determined for each compound did not vary much from cell to cell. MEF cells were 10-fold more sensitive than the other cell lines to quantify virus from mouse organs, however. Virus propagated in 3T3 and SC-1 cells were as virulent to mice as salivary gland virus, whereas virus from MEF and C127I cells was more attenuated. Overall, C127I cells were judged to be the best for large scale antiviral screening in vitro, but MEF was the cell type of choice for titration of viruses from mouse organs and tissues.

A simple method of drying virus on inanimate objects for virucidal testing.

A simple method for drying virus on inanimate objects (cover slips) under vacuum in the cold is described. Following this procedure virus maintains high titers (10(6-7)) for periods of 1-3 wk at -70 degrees C depending on the virus. For virucidal assay of disinfectants, cover slips are exposed to medium simulating the disinfectant (virus control) or disinfectant in an upright position in an Ultra-Vu cuvette. Cover slips are readily removed and placed in tissue culture medium for dilution of virus and determination of virus titer. Cytotoxicity of disinfectant is determined by exposing cover slip without virus to disinfectant, then placing it in medium, diluting the medium and incubating with the indicator cells. The use of this technique results in high titers of virus on cover slips, which are inanimate objects requiring minimal manipulation. The titration of virus or cytotoxicity in microplates is cell, medium, serum, and labware economical.

Evaluation of the anti-herpesvirus drug combinations: virazole plus arabinofuranosylhypoxanthine and virazole plus arabinofuranosyladenine.

Combinations of Virazole plus arabinofuranosylhypoxanthine (ara-Hx) and Virazole plus arabinofuranosyladenine (ara-A) were investigated in KB or BHK cells infected with types 1 or 2 herpes viruses. Combinations of Virazole and ara-Hx exhibited significant synergy as evaluated graphically (isobolograms) or by fractional inhibitory concentration (FIC) indices. Optimal ratios for the combination were 1:1 to 1:10 for Virazole to ara-Hx. At these ratios, FIC indices in the range of 0.5-0.2 were commonly observed. Combinations of Virazole and ara-A were antagonistic when observed in the presence of pentostatin, an adenosine deaminase inhibitor. In the absence of pentostatin, the minimum inhibitory concentration (MIC) of ara-A and degree of synergy with Virazole were variable.

Phosphorus in swine. V. Interrelationships of various feedlot performance, serum minerals, structural soundness and bone parameters in barrows, boars and gilts.

Daily gain, daily feed intake, feed per unit of gain, serum Ca, serum P, serum Mg, structural soundness scores, foot pad scores, metacarpal breaking force and metacarpal ash values from five Ca P trials with barrows, gilts or boars were subjected by sex in each trial to multivariate analysis of variance. Correlation coefficients were obtained from the residual sums of squares and sum of products; thus, coefficients were corrected for treatment effects. Individual values were used for all comparisons except those involving daily feed and feed/gain, for which pen means were used. High positive correlations were observed between daily gain and daily feed; there was no relationship between daily gain and feed/gain, but daily feed was positively correlated with feed/gain. Serum Ca levels were not highly correlated with daily gain, daily feed or feed/gain. Although all coefficients were less than .5, serum P was positively (P less than .01 or less than .05) related to daily gain. Serum Ca and serum Mg concentrations were unrelated to serum P concentrations, but serum Ca was positively correlated with serum Mg. There was no relationship between daily gain and soundness or pad scores. Although there were some inconsistencies, a positive relationship was observed between daily gain and metacarpal dried weight, and between daily gain and breaking strength. There appeared to be little, if any, relationship between daily feed and feed/gain and bone parameters. Ca, P and Mg were not consistently related to metacarpal dried weight, breaking strength or ash. Dried weight was positively correlated to breaking strength in four trials and to ash in two trials. Breaking strength was correlated to ash in only one trial. These results offer no support for the belief that stronger, denser bones produce more structurally sound animals, because soundness and pad scores were not related to bone parameters.