Yeasts in the gastrointestinal tract of preweaned calves and possible involvement of Candida glabrata in neonatal calf diarrhea

To examine the possibility of a mycotic involvement in neonatal calf diarrhea (NCD) the presence of fungi was assessed in (a) the intestinal contents of dead calves and fecal samples submitted for routine laboratory examination, (b) fecal specimens, sampled once in winter and once in summer, of calves raised on 2 farms with different management systems, and (c) mucosal scrapings of various segments of the digestive tract of a diarrheic calf, massively shedding Candida glabrata. C. glabrata was the most prevalent fungal species isolated from the routine samples. It was the only fungus which was shed by the calves on the 2 farms, for continuous, more or less prolonged periods, but exclusively in the winter months. Diarrhea and C. glabrata shedding seemed to be associated. C. glabrata colonized the abomasum (the functional equivalent of the monogastric stomach) but not the other segments of the digestive tract of the euthanized calf. Based on the findings of this study it seems that while some yeast species may be considered as commensals of the digestive tract of calves, and consequently their isolation from intestinal contents or fecal samples has no clinical significance, others, such as C. glabrata may be involved in enteric pathogenic processes. Moreover, characteristics of the culture, previous chemotherapeutic treatments, the animal's age and possibly climatic conditions should be taken into account before deciding on the fungal isolate's clinical relevance. Determination of mycotic involvement in NCD by routine mycological examination of intestinal contents and fecal samples of diarrheic calves may be useful to avoid unnecessary and potentially harmful antibacterial therapy.

Bovine leukemia virus-gp51 antigen expression is associated with CD5 and IgM markers on infected lymphocytes

Cows that develop a persistent lymphocytosis (PL) as a result of bovine leukemia virus (BLV) infection develop massive proliferation of B-lymphocytes expressing both IgM and CD5 markers. The association of these two markers on peripheral blood mononuclear cells (PBMC) derived from BLV-infected cows and also expressing BLV-gp51 antigen marker on these cells was determined by three-color cytometric analysis. After in vitro cultivation of PBMC in the presence of PHA for 24 h, the mean percentages of marker-reactive cells of five PL+ cows were as follows; 43% +/- 4.5 of the PBMC expressed BLV-gp51 antigen; 90% +/- 1.6 of these cells expressed both IgM and CD5 at the same time, whereas but 7.5% +/- 1.9 expressed only IgM and 2.9% +/- 0.4 expressed only CD5. The PBMC, IgM positive cells accounted for 77.8% +/- 6.8, while both CD5 and BLV-gp51 were detected simultaneously on 52.0% +/- 2.4 of the IgM+ cells, while the CD5 marker and BLV-gp51 antigen were detected independently on 35.0% +/- 1.9 and in 9.0% +/- 3.1, respectively of the IgM+ cells. Of the CD5+ cells (equivalent to 75.5% +/- 9.0 of the PBMC), 54.7% +/- 4.7 expressed simultaneously IgM and BLV-gp51, while BLV-gp51 and IgM were expressed separately by 3.0% +/- 0.5 and 37.8% +/- 3.3, respectively. An association between the B-cell phenotype and BLV tropism might exist. It is also possible that cells bearing both IgM and CD5 markers are the main target cells for BLV infection.

Enhanced antibody response in cattle against Leptospira hardjo by intradermal vaccination

A commercial killed Leptospira hardjo vaccine (with adjuvant) and non-adjuvanted preparation of the same vaccine were used in comparison of the effectiveness of the intradermal (i.d.) and subcutaneous (s.c.) routes for these vaccines. The tests were conducted in 50 females aged 6-14 months. After the first vaccination, both types of vaccine elicited a very poor antibody response by both routes of vaccination. However, after booster vaccination, the commercial vaccine (with adjuvant) elicited a remarkable immune response which was twice as high by i.d. compared with s.c. vaccination. No local or general adverse reactions were observed after i.d. vaccination with the adjuvanted commercial vaccine (potassium aluminium sulphate).

Effect of permeabilization on peripheral blood lymphocytes of bovine leukemia virus (BLV)-infected cattle

Cell surface proteins serve as markers for immunophenotypic characterization of lymphocyte subsets by appropriate monoclonal antibodies and fluorescence-activated cell sorter (FACS) analysis. By the same method, internal antigens or those that are only partially expressed on the cell surface can be determined after permeabilization of the cells. Peripheral blood lymphocytes obtained from bovine leukemia virus (BLV)-infected cattle and from BLV-free cattle were permeabilized and several lymphocyte populations were examined. BoCD4, BoCD8 and three CD4 CD8-T-cell subsets retained their original frequencies after permeabilization in both groups of animals. The recognition of the B-B2 lymphocyte molecule was only partially expressed on the cell surface of intact lymphocytes and was further revealed on permeabilization. The frequency of permeabilized, but not intact, cells stained with this mAb was significantly higher for BLV-infected cattle than for BLV-free animals (P = 0.006). Reactivities of an anti-heat shock protein (Hsp) 70 were measured before and after permeabilization of PBLs. Similar increased cell frequencies were obtained for both groups of bovines. These data indicate that flow cytometry studies should be conducted on both permeabilized and intact cells for a better assessment of protein expression on the cell surface, as well as in the cytoplasm.

Levels and role of cytokines in bovine leukemia virus (BLV) infection

Bovine leukemia virus belongs to a small subfamily of exogenous retroviruses that includes the human retroviruses HTLV-1, HTLV-II and the simian virus, STLV-1. Like other retroviruses, infection with BLV results in deregulation of the host immune system at both humoral and cellular levels. An approach which might help in the elucidation of some immune impairment phenomena is the investigation of the role that cytokines play in the pathogenesis and immune response of BLV infected animals. Here we describe our findings on IL-6 and TNF. We have found that the levels of IL-6 in the sera of BLV infected cows which show persistent lymphocytosis (BLV+ PL+) were significantly higher than those of BLV infected with no lymphocytosis (BLV+ PL-) or BLV negative cows (BLV-). The same results were obtained by measuring the spontaneous production of IL-6 in peripheral blood mononuclear cells (PBMC). Furthermore, PBMC derived from BLV+PL+ cows secrete higher levels of IL-6 and TNF alpha than those derived from BLV+PL- and BLV- ones following in vitro exposure to the BLV gp51 antigen, bacterial endotoxins (LPS) and ConA. Similar results were obtained when supernatants from stimulated adherent (monocytes, macrophages) and non-adherent cells (B and T lymphocytes) were tested. When exogenous IL-6 and TNF alpha were added to BLV infected cells in vitro, the expression of viral antigens was strongly suppressed. Thus, the possibility exists that the elevated production of IL-6 and even more than that of TNF alpha play a role as contributing factors to the latency of the clinical expression in BLV infection.

Detrimental effect of bovine leukemia virus (BLV) on the immunological state of cattle

Bovine leukemia virus (BLV) is a retrovirus which seems to affect both the humoral and the cellular immune response. Cows affected by enzootic bovine leukemia (EBL) showed a reduction of IgM-producing cells in the spleen and lymph nodes. Experimentally infected calves had lower levels of secretory IgM and a decrease in T lymphocytes in the peripheral blood. The reduction in the amount of T cells was noticed mainly in cells bearing the CD4 markers. BLV-infected animals showed diminished responsiveness to newly encountered antigens. Cows naturally infected by BLV produced Igs with impaired structural or biological reactivity. The primary immune response was shown to be deficient in BLV-infected cows following vaccination with synthetic antigen. A marked shift in the proportion of PBL, especially of the CD5+ subset, was noticed. Peripheral blood mononuclear cells from BLV-infected cows secrete elevated levels of certain cytokines and contain increased levels of cytokine mRNA. High levels of cytokines are also found in the sera of BLV-infected cows compared to non-infected animals. A correlation was found between BLV infection and lack of spontaneous recovery from Trichophyton verrucosum infection. Moreover, some studies ascertained a significant association between the herd BLV infection status and disease incidence. The culling rate was higher and milk production lower in BLV-infected vs. BLV-free herds. It seems that BLV infection affects the immune system of a cow to such an extent that it ceases to be productive enough to be kept and, in most cases, the animal is culled before any symptoms of illness associated with persistent immunodeficiency become apparent.

Protein kinase C mu is located at the Golgi compartment

Protein kinase C mu (PKC mu) displays unusual structural features like a pleckstrin homology domain and an amino-terminal hydrophobic region with a putative leader peptide and transmembrane sequence. As a discrete location often is a direct clue to the potential biological function of a kinase, antibodies directed against unique amino- and carboxy-terminal domains of PKC mu were used to localize the protein within intracellular compartments in immunofluorescence and subcellular fractionation studies. Confocal laser scanning microscopy showed colocalization of PKC mu with the resident Golgi marker protein beta 1,4 galactosyltransferase in PKC mu transfectants and in the human hepatocellular carcinoma cell line HepG2, expressing endogenous PKC mu. Long-term treatment of cells with brefeldin A, which disintegrates the Golgi apparatus, disrupted PKC mu-specific staining. Cosegregation of PKC mu with beta 1,4 galactosyltransferase, but not with the endosomal marker rab5, upon density gradient fractionation and Western blot analysis of HepG2 cell extracts, provides independent evidence for a Golgi localization of PKC mu. Moreover, cellular sulfate uptake and Golgi-specific glycosaminoglycan sulfation was enhanced in PKC mu transfectants. Together, these data suggest that PKC mu is a resident protein kinase of the core Golgi compartment and is involved in basal transport processes.

The association between tumour necrosis factor-alpha, interleukin-6 and microbiological findings in the synovial fluid of aborted and neonatal calves

Tumour necrosis factor-alpha (TNF alpha) and interleukin-6 (IL-6) were detected in the intra-carpal synovial fluids collected from aborted and recently dead young calves. Five out of seven TNF-alpha positive joint fluids were bacteriologically positive and two were sterile. Only one out of 20 TNF-alpha negative joint aspirates was infected (P = 0.0014). Sixteen of the synovial fluid samples were examined for the presence of IL-6. In 12 samples IL-6 was detected, six of which were bacteriologically contaminated. Four out of the 16 samples were IL-6 negative. These findings indicated the possible association between TNF-alpha and the intra-articular inflammatory processes in young calves, which in the present study were either found in combination with or without IL-6.

gamma delta T-lymphocytes and anti-heat shock protein reactivity in bovine leukemia virus infected cattle

Bovine leukemia virus (BLV) induces a chronic infection in cattle that may result in persistent lymphocytosis (PL) and, sometimes, enzootic bovine leukosis. The cellular and humoral immune responses of the host following infection have been extensively investigated but little is known about the involvement of gamma delta T-cells in BLV pathogenesis. The affluence of these cells in cattle, and particularly in the peripheral blood of young ruminants, may suggest a particular role for them in defense mechanisms. In this study we have examined circulating gamma delta lymphocytes that express workshop clusters 1 (WC1) and 2 (WC2). In healthy cattle the WC1 cell count tends to decrease with age and adult cattle blood has statistically lower numbers (19.0 +/- 6.6%) than that of young animals (40.1 +/- 7.2%). However, in the blood of BLV-seropositive adult cattle and mainly in BLV+ PL+ animals the population of WC1 cells is elevated compared with uninfected animals (P < 0.007). Likewise, the WC2 cells count is increased (P < 0.01) in BLV+PL+. Furthermore, we have investigated whether BLV infection up-regulates the expression of heat shock proteins (HSP) which in turn could augment the humoral response. Anti-HSP70 activity was examined in the sera of 34 BLV-infected cattle and 40 healthy controls by ELISA. Significantly higher activities (P < 0.001) were observed in BLV-infected cattle.

A possible linkage between gonadal hormones, serum and uterine levels of IgG of dairy cows

We have investigated the possible linkage between serum and uterine fluid immunoglobulin G (IgG) levels and the hormonal status of the cow. In cycling cows there was a significant (P < 0.01) drop in average (of 4 consecutive days) serum IgG levels, from 36.4 +/- 6.7 mg ml-1 during the luteal phase of the estrous cycle to 28.3 +/- 5.3 mg ml-1 during and around estrus. In prepartum cows, there was a significant drop (P < 0.01) from an average of 37.6 +/- 3.7 mg ml-1 from 5 consecutive days, i.e. 11-7 before parturition, to 28.0 +/- 5.5 mg ml-1 on the day of parturition. Total IgG in the uterine fluid ranged from 30 to 115 mg in one horn and from 24 mg ml-1 to 70 mg ml-1 in the other horn during the luteal phase, but was essentially undetectable at estrus. The drop in serum and uterine IgG occurred concomitantly with the drop in peripheral serum progesterone, from 2-3 ng ml-1 at the luteal phase, and 11-7 days before calving to less than 0.5 ng ml-1 around estrus and calving. Data suggest a possible linkage between steroid hormone and IgG levels.

Reporting on QI efforts for internal and external customers

BACKGROUND

In April 1993 the Methodist Hospital of St Louis Park, Minnesota, released its first internal quality report on outcomes and quality improvement (QI) initiatives. When a local television news reporter mentioned the report in a segment on health care quality, public interest led the hospital to launch an annual series of external quality reports in addition to its internal quality reports. When the eight-page external report was first released in 1994, consumer response was weak, but the report generated a strong response from the mass media, trade publications, the business community, and other health care organizations nationwide.

DATA COLLECTION AND USE

Data on sentinel events and outcomes analysis of a variety of clinical and administrative functions have assisted in identifying opportunities for improvement. For example, the hospital monitors the five-year survival rate for patients with myocardial infarction. With the adoption of treatment with streptokinase, data indicated frequent hypotension. Increase of infusion from 30 to 60 minutes led to a decrease in hypotension.

THE REPORTS

The external report included, in shorter and simpler form, almost all the sections in the internal report, such as QI activities (teams, training, critical paths), clinical outcome measures, community health, patient satisfaction, value, and accreditation. The indicators included in the external report were selected to minimize potential misinterpretation by public audiences.

CONCLUSIONS

By increasing the visibility of QI within the hospital, the internal quality reports have helped generate further QI activity, and the external report augmented further positive publicity among the local health care press. The reports are proven effective tools for communicating the hospital's ability to sustain and improve the quality of its services over time.

Helium and lower oxygen concentration do not prolong tracheal tube ignition time during potassium titanyl phosphate laser use

BACKGROUND

Tracheal tube fire is a well recognized complication of airway laser procedures. The use of helium in the anesthetic gas mixture delays the ignition time of polyvinyl chloride tracheal tubes when a carbon dioxide laser is used. The effects of helium gas mixtures on potassium titanyl phosphate (KTP) laser-induced tracheal tube ignition have not been studied.

METHODS

One hundred forty unmarked polyvinyl chloride tracheal tube segments were exposed to KTP or carbon dioxide laser beams. Each tube segment was suspended in a burn chamber with varying mixtures of oxygen in either nitrogen or helium. The gas mixtures were 21%, 30%, and 40% O2 in N2 or 30% and 40% O2 in helium. Fourteen tube segments were tested for each gas mixture. The ignition time was recorded for each segment. The laser beam was turned off at 60 s if ignition did not occur.

RESULTS

At 30% O2/N2, mean ignition time with the carbon dioxide laser was 41.3 +/- 10.8 s (mean +/- standard deviation), whereas at 30% O2/He, the mean ignition time was 60 +/- 0 s. Increasing the oxygen concentration to 40% significantly shortened the ignition time with both helium and nitrogen for the carbon dioxide laser. With the KTP laser, ignition time varied greatly at any oxygen concentration. At 30% O2/N2, median ignition time with the KTP laser was 6.9 s (mean time 15.6 +/- 19.5 s), whereas at 30% O2/He, median time was 8.6 s, (mean time 9.9 +/- 5.33 s). No statistically significant differences were found for the ignition times in the KTP laser groups.

CONCLUSIONS

Using helium instead of nitrogen with oxygen delays unmarked polyvinyl chloride tracheal tube ignition time when the tube segments are exposed to a carbon dioxide laser beam as compared to a KTP laser. The different laser wavelengths and penetration properties may produce this difference. The helium protocol previously described has been proven safe only with the carbon dioxide laser and should be tested with other laser types before being used clinically with these lasers.

Use of the electrocardiogram in a pediatric emergency department

OBJECTIVE

To ascertain the quality of electrocardiogram (ECG) use in a pediatric emergency department (PED).

RESEARCH DESIGN

Patient series.

SETTING

Pediatric emergency department in a university-based hospital.

PARTICIPANTS

Seventy patients, aged 2 months to 22 years.

MEASUREMENTS

All ECGs obtained in the PED were received by the Division of Pediatric Cardiology during the 15-month study period. The charts of all patients were then reviewed to determine the (1) indications for obtaining an ECG; (2) accuracy of documentation; (3) impact of ECG results on the treatment of patients; and (4) concordance between PED and pediatric cardiologists in ECG interpretation.

RESULTS

Chest pain was the most commonly documented indication, accounting for 54% of the ECGs obtained. Other indications were suspected arrhythmias (11%), seizure and syncope (11%), drug exposure (8%), and miscellaneous (16%). Twelve charts (17%) lacked documentation of ECG results. Ten ECGs (14%) were performed improperly. Twenty three (32%) were interpreted differently by the pediatric cardiologists; 14 ECGs (20%) had potential clinical relevance. Thirty-seven (52%) ECGs were useful in patient care; this was significantly associated with the presence of a PED attending (P = .03 by Fisher's Exact Test).

CONCLUSION

We recommend education of pediatric residents in ECG interpretation and subsequent review by a pediatric cardiologist of each ECG performed in the PED.

Vaccination of chickens with live fowl pox (FP) vaccine in oil

Live fowl pox (FP) vaccine was adjuvanted in oil just prior to the subcutaneous (SC) vaccination of one day old chicks and adult chickens. The birds were challenged by the wing web (WW) method and absence of "takes" were considered as protection. On 21 day post challenge, 90%-100% of the chicks or chickens were protected while on day 9 post challenge 60% were protected. Full protection of the live-in-oil adjuvanted vaccine is probably somewhat delayed as compared to protection endowed by the liquid vaccine. Incorporation of live FP vaccine in two different kinds of commercial Newcastle disease (ND) killed vaccine in oil, was shown to endow full protection following SC administration.

BLV-infected lymphocytes exhibit two patterns of expression as determined by Ig and CD5 markers

Lymphocytes were defined by their cell surface markers, Ig and CD5 in three groups of cows naturally infected with bovine leucosis virus (BLV). Lymphocytes were enumerated and groups were designated BLV seropositive with persistent lymphocytosis (BLV + PL +), BLV seropositive without persistent lymphocytosis (BLV + PL-) and BLV negative. The competence of peripheral blood mononuclear cells (PBMC) from the tested cows to express these two markers was determined by the double staining immunofluorescence procedure. Cows which developed persistent lymphocytosis (PL) as a result of BLV infection consequently underwent massive proliferation of B lymphocytes which express both Ig and CD5 antigens. In contrast, cows which were defined as BLV positive and PL negative showed a remarkable decrease of CD5 + Ig-, CD5- Ig+ and CD5+ Ig+ cells and also in the total number of lymphocytes. We suggest that BLV infection affects bovine lymphocytes through two different pathways of expression which might be related to the genetic properties of the target cells.

Recognition of the aberrant right subclavian artery on cervical spine MR

Neuroradiologists performing cervical spine MR scans are reminded that an aberrant right subclavian artery is detectable on sagittal cervical spine views. This review of 335 consecutive patients revealed two such anomalies for a prevalence of 0.6%, which compares favorably with the published range of occurrences in the literature (0.5 to 2%).

Immunization of chickens with live Newcastle disease vaccine adjuvanted with oil

Chickens of various ages and breeds were vaccinated subcutaneously with Newcastle disease live-in-oil vaccines. These vaccines were prepared immediately prior to the vaccination by mixing the lyophilized live vaccine with the oil adjuvant, which was kept at room temperature. The live-in-oil vaccines were shown to be 30-50 times more effective in efficacy tests than either the same vaccines reconstituted in water or killed-in-oil vaccines. In addition to its biological advantage, the method of preparation of live-in-oil vaccine saves the expensive space of cold storage and shipment necessary for conventional killed-in-oil vaccines.

Hemorrhagic necrosis and vascular injury in carbon monoxide poisoning: MR demonstration

MR imaging of a patient 3-years status post-carbon monoxide (CO) poisoning revealed areas of abnormal signal bilaterally in the region of the globus pallidus that had shorter T1 characteristics and longer T2 characteristics than cerebrospinal fluid, probably representing methemoglobin, and that is surrounded by a rim of decreased signal on T2-weighted images, felt to represent hemosiderin. This case demonstrates characteristic findings on MR imaging of CO poisoning, as well as observations that suggest prior focal hemorrhage. Typical findings, neuropathology, and the role of vascular injury and prognosis are discussed.

Differences in protection between heavy and light breeds of chickens following vaccination with Newcastle disease vaccines-a survey of data, 1971 to 1990

Data obtained over 20 years of Newcastle disease vaccine testing were statistically analyzed. The protection afforded heavy and light breeds of chickens was compared following challenge (efficacy) after vaccination with live and inactivated vaccines produced from different virus strains. Standard challenge virus was used throughout the period. The data show that the heavy breeds were significantly inferior in their protectability when compared with the light breeds. This inferiority was shown after vaccination with all types of vaccines. It is suggested that heavy and light breeds of chickens differ genetically in their acquired resistance to Newcastle disease virus, although difference in susceptibility to the virus as a pathogen cannot be ruled out entirely.

Circulating immune complexes in bovine leukemia virus (BLV)-infected cattle

Circulating immune complexes (ICs) were detected in the sera of bovine leukemia virus (BLV)-seropositive cattle. Immune complexes were precipitated in 2.5% polyethylene glycol (PEG) and further dissociated. Bovine leukemia virus antigens, IgG and IgM molecules were detected after solubilization in the presence of sodium dodecyl sulphate, and quantitated by enzyme-linked immunosorbent assay (ELISA) assays. Mean values of IgG and IgM in BLV-containing ICs did not significantly differ from those obtained from ICs originating from BLV-seronegative animals. However, differences were found in the composition of ICs from older BLV-positive animals as compared to those obtained from young animals. The ratio of IgG/IgM was 5.02 in animals aged 5-10 years, while this ratio was 11.66 in animals of less than 5 years of age and 10.19 in controls. This might indicate a possible increase in the contribution of IgM molecules to the structural composition of ICs in BLV-infected cattle as related to age or stage of infection.

The riddle of the uvula

Since ancient times, the uvula has been a subject of interesting and contradictory observations. On the one hand, it was regarded as having a functional role in speech and in immunology, but on the other hand it was regarded as a potentially hazardous organ, possibly responsible for sudden infant death syndrome. None of these hypotheses, however, has been proved. In a previous study on patients undergoing uvulopalatopharyngoplasty, we suggested that the most important function of the uvula is connected with the muscularis uvula. Its function could be related to drinking while bending over. This previous assumption was that the uvula is a phylogenetic remnant from mammals that drink while bending their neck downward. In the present study, the soft palate of eight different mammals was macroscopically and microscopically studied and compared. Of all animals in the study, a small underdeveloped uvula was found only in two baboons. We found that the human uvula consists of an intermix of serous and seromucous glandular masses, muscular tissue, and large excretory canals. The serous and seromucous glands are absent in the other mammals. Thus, the uvula is a highly sophisticated structure, capable of producing a large quantity of fluid saliva that can be excreted in a short time. Both uvula and speech serve to differentiate human beings from animals. Our conclusion is that the uvula is possibly an accessory organ of speech, and may be another marker of human evolution that differentiates man from other mammals.

A lactogenic-immune-deficiency-syndrome in cows: unexplained phenomenon

The majority of adult cows in a certain dairy herd, were found to have very low levels of immunoglobulins (Igs) in their colostrum. This phenomenon was defined by us as Lactogenic-Immune-Deficiency-Syndrome (LIDS). The mean IgG levels were 44.5 and 57.2 mg ml-1 respectively (on two different occasions) as compared to that of a control group which was 103.4 mg ml-1. The levels of Igs in the colostra of heifers from the same herd were found to be higher than those of adult cows. The degree of LIDS was found to be closely related to the age of cows in the herd. The low levels of Igs in the colostra were not directly linked to their concentrations in the sera of the affected cows. The relatively low amount of IgA in the affected colostra suggests that the local production in the lymph tissue associated with the mammary glands is impaired as well. In order to investigate the etiology of the phenomenon, tests were carried out to reveal whether bovine leucosis virus (BLV) infection or immune complexes were involved in the pathogenesis of LIDS. The results were negative. The etiology of LIDS remains for the time being unknown.

Cerebral aspergillosis: MR imaging and histopathologic correlation

The authors report a case of intracranial aspergillosis secondary to immunosuppression. Signal intensity changes in the lesion on brain MR are compared with gross and histopathologic findings at autopsy. A peripheral ring of low signal intensity relates to a dense population of Aspergillus hyphal elements and small areas of hemorrhage. CT findings are included for comparison.

Effect of two novel inhibitors of the human immunodeficiency virus protease on the maturation of the HIV gag and gag-pol polyproteins

The ability of two novel synthetic compounds to inhibit the HIV protease-mediated processing of HIV-1 precursor polyproteins was investigated in an in vitro gag-protease mixed lysate assay system and in an assay using recombinant baculoviruses engineered to express the HIV-1 gag and pol genes in cultured insect cells. With the in vitro mixed lysate assay we have shown that both compounds at 1 microM can completely inhibit the HIV-1 and HIV-2 protease-mediated release of p24 from the HIV-1 gag precursor at pH 5.5 and pH 7.0. In the intracellular baculovirus system these compounds were shown to inhibit the protease-mediated maturation of gag and also the excision of the protease moiety from its precursor.