Evaluation of VIDAS® Immuno-Concentration Salmonella (ICS)/VIDAS Salmonella (SLM) Immunoassay Method for Detection of Salmonella in Selected Foods (Method Modification 2001.09): Collaborative Study

A new method for detection of Salmonella in foods in a minimum of 24 h was adopted as an AOAC Official First Action Method for selected foods (2001.09) using both the VIDAS Immuno-Concentration Salmonella (ICS) and VIDAS Salmonella (SLM) methods.

Evaluation of VIDAS® Salmonella (SLM) Immunoassay Method with Rappaport-Vassiliadis (RV) Medium for Detection of Salmonella in Foods: Collaborative Study

A collaborative study was conducted to compare the VIDAS Salmonella (SLM) with Rappaport-Vassiliadis (RV) method for detection of Salmonella in foods to the current standard method presented in the U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM) and the culture method presented in AOAC's Official Methods of Analysis. The VIDAS SLM with RV method uses tetrathionate broth in combination with RV medium in place of selenite cystine broth for selective enrichment, thereby eliminating the hazardous waste issue for laboratories. Twenty five laboratories participated in the evaluation, each testing one or more of 8 test products: nonfat dry milk, dried egg, soy flour, lactic casein, milk chocolate, raw ground pork, raw ground turkey, and raw peeled shrimp. Results of the study showed no significant differences in the numbers of confirmed positive samples with the VIDAS SLM with RV procedure and the BAM/AOAC culture procedure. The VIDAS SLM with RV method was effective for rapid detection of Salmonella in foods. It is recommended that AOAC INTERNATIONAL modify the VIDAS Salmonella SLM procedure to include the RV method.

Evaluation of VIDAS® Immuno-Concentration Salmonella/VIDAS Salmonella Immunoassay Method for Detection of Salmonella in Selected Foods: Collaborative Study

The VIDAS Immuno-concentration Salmonella (ICS)/VIDAS Salmonella (SLM) immunoassay method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Thirty-two laboratories participated in the evaluation. Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. The 2 methods were in agreement for 1266 of the 1440 samples. Of the 174 samples not in agreement, 69 were VIDAS ICS/SLM-positive and BAM/AOAC-negative and 105 were VIDAS ICS/SLM-negative and BAM/AOAC-positive.

Evaluation of VIDAS® Immuno-Concentration Salmonella Assay Plus Selective Plate Method (Hektoen Enteric, Bismuth Sulfite, Salmonella Identification) for Detection of Salmonella in Selected Foods: Collaborative Study

The VIDAS Immuno-concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, bismuth sulfite, Salmonella identification) method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Thirty-two laboratories participated in the evaluation. Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. The 2 methods were in agreement for 1283 of the 1440 test samples. Of the 157 test samples not in agreement, 82 were VIDAS ICS plus selective plate-positive and BAM/AOAC-negative, and 75 were VIDAS ICS plus selective plate-negative and BAM/AOAC-positive.

3M™ Petrifilm™ Staph Express Count Plate Method for the Enumeration of Staphylococcus aureus in Selected Types of Meat, Seafood, and Poultry: Collaborative Study

The 3M™ Petrifilm™ Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Four foods—cooked, diced chicken; cured ham; smoked salmon; and pepperoni—were analyzed for S. aureus by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 4 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.

Salmonella in Selected Foods by VIDAS® Immuno-Concentration Salmonella Plus Selective Plate Method (Hektoen Enteric, Xylose Lysine Desoxycholate, Bismuth Sulfite): Collaborative Study

The VIDAS Immuno-concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, xylose lysine desoxycholate, bismuth sulfite) method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Thirty-two laboratories participated in the evaluation. Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. The 2 methods were in agreement for 1297 of the 1455 samples. Of the 158 samples not in agreement, 82 were VIDAS ICS plus selective plate-positive and BAM/AOAC-negative, and 76 were VIDAS ICS plus selective plate-negative and BAM/AOAC-positive.

Evaluation of VIDAS Salmonella (SLM) immunoassay method with Rappaport-Vassiliadis (RV) medium for detection of Salmonella in foods: collaborative study

A collaborative study was conducted to compare the VIDAS Salmonella (SLM) with Rappaport-Vassiliadis (RV) method for detection of Salmonella in foods to the current standard method presented in the U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM) and the culture method presented in AOAC's Official Methods of Analysis. The VIDAS SLM with RV method uses tetrathionate broth in combination with RV medium in place of selenite cystine broth for selective enrichment, thereby eliminating the hazardous waste issue for laboratories. Twenty five laboratories participated in the evaluation, each testing one or more of 8 test products: nonfat dry milk, dried egg, soy flour, lactic casein, milk chocolate, raw ground pork, raw ground turkey, and raw peeled shrimp. Results of the study showed no significant differences in the numbers of confirmed positive samples with the VIDAS SLM with RV procedure and the BAM/AOAC culture procedure. The VIDAS SLM with RV method was effective for rapid detection of Salmonella in foods. It is recommended that AOAC INTERNATIONAL modify the VIDAS Salmonella SLM procedure to include the RV method.

Evaluation of VIDAS Immuno-Concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, bismuth sulfite, Salmonella identification) for detection of Salmonella in selected foods (Method Modification 2001.07): collaborative study

A new method for detection of Salmonella in foods in 48 h has been granted AOAC First Action approval in selected foods (Official Method 2001.07) using both the VIDAS Immuno-Concentration Salmonella (ICS) method and a combination of 3 selective plates: Hektoen enteric (HE), bismuth sulfite (BS), and Salmonella Identification (SMID).

Evaluation of VIDAS Immuno-Concentration Salmonella (ICS)/VIDAS Salmonella (SLM) immunoassay method for detection of Salmonella in selected foods (Method Modification 2001.09): collaborative study

A new method for detection of Salmonella in foods in a minimum of 24 h was adopted as an AOAC Official First Action Method for selected foods (2001.09) using both the VIDAS Immuno-Concentration Salmonella (ICS) and VIDAS Salmonella (SLM) methods.

3M Petrifilm Staph Express Count plate method for the enumeration of Staphylococcus aureus in selected types of meat, seafood, and poultry: collaborative study

The 3M Petrifilm Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Four foods--cooked, diced chicken; cured ham; smoked salmon; and pepperoni--were analyzed for S. aureus by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 4 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.

Evaluation of VIDas immuno-concentration Salmonella/VIDAS salmonella immunoassay method for detection of Salmonella in selected foods: collaborative study

The VIDAS Immuno-concentration Salmonella ICS)/VIDAS Salmonella (SLM) immunoassay method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Thirty-two laboratories participated in the evaluation. Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. The 2 methods were in agreement for 1,266 of the 1,440 samples. Of the 174 samples not in agreement, 69 were VIDAS CS/SLM-positive and BAM/AOAC-negative and 105 were VIDAS ICS/SLM-negative and BAM/AOAC-positive.

Evaluation of VIDAs Immuno-concentration Salmonella assay Plus selective plate method (Hektoen enteric, bismuth sulfite, Salmonella identification) for detection of Salmonella in selected foods: collaborative study

The VIDAS Immuno-concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, bismuth sulfite, Salmonella identification) method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Thirty-two laboratories participated in the evaluation. Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. The 2 methods were in agreement for 1,283 of the 1,440 test samples. Of the 157 test samples not in agreement, 82 were VIDAS ICS plus selective plate-positive and BAM/AOAC-negative, and 75 were VIDAS ICS plus selective plate-negative and BAM/AOAC-positive.

Salmonella in selected foods by VIDAS immuno-concentration Salmonella plus selective plate method (Hektoen enteric, xylose lysine desoxycholate, bismuth sulfite): collaborative study

The VIDAS Immuno-concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, xylose lysine desoxycholate, bismuth sulfite) method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Thirty-two laboratories participated in the evaluation. Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. The 2 methods were in agreement for 1,297 of the 1,455 samples. Of the 158 samples not in agreement, 82 were VIDAS ICS plus selective plate-positive and BAM/AOAC-negative, and 76 were VIDAS ICS plus selective plate-negative and BAM/AOAC-positive.

Parallel image segmentation using the L4 network

Each processing element in the outer plexiform layer of the fly's (Musca domestica) compound eye has a single copy of a monopolar cell called L4 whose function is still unknown. This paper proposes that L4 acts as an image segmentor receiving data from the L1 and L2 cell layer above it. The photoreceptor terminals R1 through R6 and L1 and L2 form a cartridge with shunting current inhibition that enhances contrast at the first synaptic contact. The photoreceptors feeding their respective terminals share a common optical axis. What was realized for this entire structure that led up to and included L1 and L2, was that it forms a single processing element which outputs a weighted function based on current shunting between the photoreceptor axon terminals around L1 and L2. Thus the basic biological 'algorithm' that this paper proposes for L1 and L2 involves a summation of the differences between a central reference cell (referred to as Rref) and the six neighboring photoreceptor terminals R1-R6 within the cartridge of L1 and L2. Simulation implementing this simple algorithm on a hexagonal packed matrix in Matlab, suggest that objects with even small differences in intensity with the background, can readily be distinguished from the background. This high pass filter biological model allows edge detection and segmentation, independent of scale in a parallel, modular fashion. Implementation of such a biological algorithm using analog circuitry forms a preprocessing unit that introduces virtually no delay in the processing of image information, in comparison to present DSP techniques, that require iterative approaches and costly computing time.

Comparable postoperative pulmonary atelectasis in patients given 30% or 80% oxygen during and 2 hours after colon resection

BACKGROUND

High concentrations of inspired oxygen are associated with pulmonary atelectasis but also provide recognized advantages. Consequently, the appropriate inspired oxygen concentration for general surgical use remains controversial. The authors tested the hypothesis that atelectasis and pulmonary dysfunction on the first postoperative day are comparable in patients given 30% or 80% perioperative oxygen.

METHODS

Thirty patients aged 18-65 yr were anesthetized with isoflurane and randomly assigned to 30% or 80% oxygen during and for 2 h after colon resection. Chest radiographs and pulmonary function tests (forced vital capacity and forced expiratory volume) were obtained preoperatively and on the first postoperative day. Arterial blood gas measurements were obtained intraoperatively, after 2 h of recovery, and on the first postoperative day. Computed tomography scans of the chest were also obtained on the first postoperative day.

RESULTS

Postoperative pulmonary mechanical function was significantly reduced compared with preoperative values, but there was no difference between the groups at either time. Arterial gas partial pressures and the alveolar-arterial oxygen difference were also comparable in the two groups. All preoperative chest radiographs were normal. Postoperative radiographs showed atelectasis in 36% of the patients in the 30%-oxygen group and in 44% of those in the 80%-oxygen group. Relatively small amounts of pulmonary atelectasis (expressed as a percentage of total lung volume) were observed on the computed tomography scans, and the percentages (mean +/- SD) did not differ significantly in the patients given 30% oxygen (2.5% +/- 3.2%) or 80% oxygen (3.0% +/- 1.8%). These data provided a 99% chance of detecting a 2% difference in atelectasis volume at an alpha level of 0.05.

CONCLUSIONS

Lung volumes, the incidence and severity of atelectasis, and alveolar gas exchange were comparable in patients given 30% and 80% perioperative oxygen. The authors conclude that administration of 80% oxygen in the perioperative period does not worsen lung function. Therefore, patients who may benefit from generous oxygen partial pressures should not be denied supplemental perioperative oxygen for fear of causing atelectasis.

Immune responses induced by intramuscular or gene gun injection of protective deoxyribonucleic acid vaccines that express the circumsporozoite protein from Plasmodium berghei malaria parasites

The circumsporozoite protein (CSP) is a target for effector Ab and cell mediated immunity against malaria parasites; DNA vaccination can induce both types of effector response. The immunogenicity and efficacy of two DNA plasmids expressing different amounts of Plasmodium berghei CSP were evaluated by immunizing BALB/c mice i.m. or epidermally and by varying the number of immunizations (one to three doses) and the interval between immunizations. Expanding the interval gave the strongest effect, increasing efficacy and antibody boosting, and, in the case of epidermal vaccination, promoting a switch in CSP-specific IgG isotypes from IgG1 to a balance with IgG2a. The strongest humoral immune response and the greatest level of protection were induced by vaccinating epidermally with high expresser plasmid, using a gene gun to administer three doses at 6-wk intervals. For this group, the mean, repeat-specific, prechallenge antibody titer among mice not infected after challenge was significantly higher than that in infected mice, but the mean prechallenge titers for antibody reactive with whole sporozoites were not significantly different. The interval-dependent induction of IgG2a antibodies by epidermal vaccination contradicts the widely held belief that antibody responses induced by this method are restricted to those that are Th2 dependent.

Immune responses induced by intramuscular or gene gun injection of protective deoxyribonucleic acid vaccines that express the circumsporozoite protein from Plasmodium berghei malaria parasites

The circumsporozoite protein (CSP) is a target for effector Ab and cell mediated immunity against malaria parasites; DNA vaccination can induce both types of effector response. The immunogenicity and efficacy of two DNA plasmids expressing different amounts of Plasmodium berghei CSP were evaluated by immunizing BALB/c mice i.m. or epidermally and by varying the number of immunizations (one to three doses) and the interval between immunizations. Expanding the interval gave the strongest effect, increasing efficacy and antibody boosting, and, in the case of epidermal vaccination, promoting a switch in CSP-specific IgG isotypes from IgG1 to a balance with IgG2a. The strongest humoral immune response and the greatest level of protection were induced by vaccinating epidermally with high expresser plasmid, using a gene gun to administer three doses at 6-wk intervals. For this group, the mean, repeat-specific, prechallenge antibody titer among mice not infected after challenge was significantly higher than that in infected mice, but the mean prechallenge titers for antibody reactive with whole sporozoites were not significantly different. The interval-dependent induction of IgG2a antibodies by epidermal vaccination contradicts the widely held belief that antibody responses induced by this method are restricted to those that are Th2 dependent.

Peri-operative thoracic epidural analgesia for thoracotomy

In a prospective study, experiences with peri-operative thoracic epidural analgesia (TEA) for thoracic surgery were documented. Two hundred and seven patients scheduled for elective thoracotomy were investigated. All patients received thoracic epidural catheters 2 h pre-operatively. The catheters were inserted between T4-5 and T8-9 intervertebral spaces. Epidural medication with bupivacaine and fentanyl was started preoperatively, maintained throughout surgery and was continued post-operatively via patient controlled analgesia (PCA) devices. Patients were anaesthetized with propofol and tracheal intubation was performed following neuromuscular blockade with vecuronium. Ninety-five percent of the patients were extubated immediately after surgery. 70.5% of all the patients had excellent post-operative analgesia (VAS pain scoring 0-2) on the day of surgery, 78% the day after surgery and 91% on the second day after surgery. Additionally early post-operative mobilization could be started in 63% of all patients. No neurological sequelae caused by thoracic epidural catheterization was seen in the early post-operative period.

Early cardiorespiratory patterns in severely burned patients with concomitant inhalation injury

Hemodynamic and oxygenation parameters were determined during the first 24 h in 13 burned patients with concomitant inhalation injury (burn surface area 40-60 percent). In all patients right ventricular function was severely compromised evidenced as a significant increase in end-diastolic volumes, decrease in ejection fractions, low stroke work indices and increased pulmonary vascular resistances. Inotropic support with dobutamine and careful titration of volume infusion according to end-diastolic volume indices improved the hemodynamics as demonstrated by significant increases in right ventricular ejection fractions in all patients without any changes in mean arterial pressures, urine output and oxygenation. Assessment of ventricular performance by a specially designed pulmonary artery catheter is helpful in the management of severely burned patients with concomitant inhalation injury.

Postdural puncture headache and back pain after spinal anesthesia with 27-gauge Quincke and 26-gauge Atraucan needles

BACKGROUND AND OBJECTIVES

The purpose of this study was to determine whether the 26-gauge Atraucan needle shows any benefit on the incidence of postdural puncture headache (PDPH) and back pain as compared with the 27-gauge Quincke needle.

METHODS

We investigated 388 patients, 171 men and 217 women, who were receiving spinal anesthesia for subumbilical surgery. We compared spinal anesthesia via the 27-gauge Quincke needle in 202 patients (group Q) and via the 26-gauge Atraucan needle in 186 patients (group A).

RESULTS

The incidence of PDPH was 2.97% (6 of 202) in group Q and 2.69% (5 of 186) in group A. The incidence of back pain was 4.95% (10 of 202) in group Q and 5.91% (11 of 186) in group A. There was no statistically significant association of needle type, age, or sex with the incidence of PDPH and back pain.

CONCLUSIONS

Both needles are associated with very low incidences of PDPH and back pain, which are not affected by which needle is chosen.

Progress and challenges toward an AIDS vaccine: Brother, can you spare a paradigm?

The development of a safe and effective vaccine for prevention of AIDS has thus far proven to be exceedingly difficult due to the complexities associated with HIV pathogenesis including but not limited to antigenic hypervariability, multiple routes and modes of transmission, a lack of defined correlates of protective immunity, and a tropism for infection of immunoregulatory cells which are essential for orchestrating an effective host immune response. Recent observations, including the identification of significant differences between primary isolates of HIV circulating in the population and laboratory-adapted isolates, animal model protection studies demonstrating prevention of AIDS-like disease progression in nonhuman primates in the absence of sterilizing immunity, and epidemiologic studies which question the current dogma surrounding HIV variation and control, have led to the development of novel approaches for antigen presentation and adjuvant development targeted at AIDS vaccine development. The goal of developing a safe and effective AIDS vaccine will likely occur when continued advances in understanding the immunopathogenesis of HIV is balanced with a healthy dose of empirical testing of innovative candidate AIDS vaccines.

Pharmacodynamics of mivacurium in severely burned patients

The pharmacodynamics of mivacurium, a new short-acting non-depolarizing muscle relaxant, were studied in nine severely burned patients with concomitant inhalation injury. Complete neuromuscular blockade was achieved within 1.3 min (controls 3.0 min) following the usually recommended intubating dose (0.15 mg/kg/BW 2 x ED95) of mivacurium. The clinical duration of neuromuscular blockade and the recovery times were slightly prolonged, due to significantly reduced serum cholinesterase activity (clinical duration 24.6 min vs. 15.3 min). This pharmacodynamic profile makes mivacurium preferable for intermittent on-demand neuromuscular blockade in the severely burned patient.

[Prolactinoma after craniocerebral trauma]

A female patient, now twenty-four years old, suffered from a severe cerebral contusion in 1983 as a result of a car accident. At the time of the accident, she had a regular menstrual cycle. Since 1985, she has contracted oligomenorrhoea and since 1988 secondary amenorrhoea. In 1988, we diagnosed by CT-scan and NMR-imaging an excessive hyperprolactinaemia caused by a pituitary adenoma. Neither surgical intervention, nor conservative medication could reduce the prolactin level to normal. We suspect, that there is an association between the cranial injury and the appearance of the pituitary tumour.

Agnus castus extracts inhibit prolactin secretion of rat pituitary cells

In our studies on prolactin inhibition by plant extracts we focused on the effects of extracts of Vitex agnus castus and its preparations on rat pituitary cells under basal and stimulated conditions in primary cell culture. Both extracts from Vitex agnus castus as well as synthetic dopamine agonists (Lisuride) significantly inhibit basal as well as TRH-stimulated prolactin secretion of rat pituitary cells in vitro and as a consequence inhibition of prolactin secretion could be blocked by adding a dopamine receptor blocker. Therefore because of its dopaminergic effect Agnus castus could be considered as an efficient alternative phytotherapeutic drug in the treatment of slight hyperprolactinaemia.

Effect of anodal high voltage pulsed current on edema formation in frog hind limbs

We have recently demonstrated that some forms of cathodal high voltage pulsed current (HVPC) curb posttraumatic edema formation in frog hind limbs. The purpose of this study was to determine, by assessing the capacity of anodal HVPC to curb posttraumatic edema formation, whether polarity is an important variable. Fourteen anesthetized bullfrogs were placed on large dispersive electrodes lining body slings that maintained the frogs' limbs in a dependent position throughout data collection. The frogs' feet were traumatized by impact following initial measurement of limb volumes. At the commencement of each of four 30-minute treatments, hind limbs were immersed in separate beakers and briefly stimulated until motor threshold was determined. One limb, randomly selected, received anodal HVPC at 90% of motor threshold and 120 pulses per second; the other limb served as a control. Treatments were followed by 30-minute rests. Limb volumes were measured by water displacement immediately after trauma and following each treatment and rest period. Data were expressed as changes from pretrauma volumes in milliliters per kilogram of body weight. A repeated-measures analysis of variance was used to test for treatment effect. Despite an aggressive series of treatments, virtually symmetrical bilateral edema occurred; therefore, no treatment effect was evident. This result contrasts with treatment effects previously reported for cathodal HVPC.

Prospects for an AIDS vaccine

Recent developments, in both animal systems and human trials, have provided encouraging results to counter the pessimism that has prevailed concerning the likelihood of obtaining an effective AIDS vaccine. This review summarizes these findings and their impact on defining and focusing the research agenda for the immediate future.

Second annual meeting of the National Cooperative Vaccine Development Groups for AIDS. 15-18 October 1989; Fort Lauderdale, Florida

In this short review of the three-day meeting on AIDS vaccine development where numerous scientific advances were described for the first time, it is nearly impossible to capture all of the highlights. Thus, areas such as advances in vaccine adjuvant development, standardized challenge pools for vaccine testing, novel approaches with retroviral vectors for construction of target cells for cellular immune assays, summaries from all of the international AIDS vaccine development programmes, and other topics which were covered at the meeting are not discussed above. In closing the meeting, W. Koff (NIAID) noted that 1989 represented the turning point for AIDS vaccine development, that pessimism had given way to cautious optimism, and that the fundamental focus had changed from 'if a vaccine could be developed' to 'when'. While several challenges still remain in the path toward development of a safe and effective vaccine, the meeting served both to focus the direction of the research agenda for the next year and to build new and stronger collaborations among the international network of scientists dedicated to the common goal of developing a safe and effective AIDS vaccine.

Unmyristylated Moloney murine leukemia virus Pr65gag is excluded from virus assembly and maturation events

The gag precursor polyprotein of Moloney murine leukemia virus (MuLV) is normally modified by myristylation of the N-terminal glycine. Previous work showed that the Pr65gag lacking the myristylation site does not associate with cellular membranes or assemble into virus particles. We now report that it also is not cleaved to the mature gag cleavage products within the cell and that it sediments as a free 65-kilodalton monomer in detergent-free cell extracts containing 0.3 M NaCl. Even when the cells containing the mutant are productively infected with wild-type MuLV, the mutant Pr65gag is not processed into cleavage products and is not incorporated into the virions produced by these cells. Thus, the mutant gag molecules seem unable to participate in the normal processes of self-assembly and maturation. We propose that myristate-mediated membrane association is an essential first step in MuLV assembly. This association may also play a role in budding of MuLV.

Molecular characterization of gag proteins from simian immunodeficiency virus (SIVMne)

A simian immunodeficiency virus (SIV) designated SIVMne was isolated from a pig-tailed macaque with lymphoma housed at the University of Washington Regional Primate Research Center, Seattle. To better establish the relationship of SIVMne to other immunodeficiency viruses, we purified and determined the partial amino acid sequences of six structural proteins (p1, p2, p6, p8, p16, and p28) from SIVMne and compared these amino acid sequences to the translated nucleotide sequences of SIVMac and human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2). A total of 125 residues of SIVMne amino acid sequence were compared to the predicted amino acid sequences of the gag precursors of SIV and HIVs. In the compared regions 92% of the SIVMne amino acids were identical to predicted residues of SIVMac, 83% were identical to predicted residues of HIV-2, and 41% were identical to predicted residues of HIV-1. These data reveal that the six SIVMne proteins are proteolytic cleavage products of the gag precursor (Pr60gag) and that their order in the structure of Pr60gag is p16-p28-p2-p8-p1-p6. Rabbit antisera prepared against purified p28 and p16 were shown to cross-react with proteins of 60, 54, and 47 kilodaltons present in the viral preparation and believed to be SIVMne Pr60gag and intermediate cleavage products, respectively. SIVMne p16 was shown to contain covalently bound myristic acid, and p8 was identified as a nucleic acid-binding protein. The high degree of amino acid sequence homology between SIVs and HIV-2 around proven proteolytic cleavage sites in SIV Pr60gag suggests that proteolytic processing of the HIV-2 gag precursor is probably very similar to processing of the SIV gag precursor. Peptide bonds cleaved during proteolytic processing of the SIV gag precursor were similar to bonds cleaved during processing of HIV-1 gag precursors, suggesting that the SIV and HIV viral proteases have similar cleavage site specificities.

Preparation of raf-oncogene-specific antiserum with raf protein produced in E. coli

In this report we describe the expression of v-raf protein in E. coli using a tryptophan-promoter-driven expression vector and its immunological characterization by anti-peptide sera. The purified recombinant protein was used to produce raf-specific antibodies which are suitable for studying v-raf and c-raf proteins in vitro and in vivo in a variety of species ranging from mouse to man.

Poorly expressed endogenous ecotropic provirus of DBA/2 mice encodes a mutant Pr65gag protein that is not myristylated

DBA/2 mice carry a single endogenous ecotropic murine leukemia provirus designated Emv-3. Although this provirus appears to be nondefective by genomic restriction enzyme mapping, weanling mice do not produce virus and only about one-third of adult mice ever express virus. 5-Iododeoxyuridine and 5-azacytidine, two potent inducers of ecotropic virus expression, are relatively ineffective at inducing Emv-3 expression. However, the chemical carcinogen 7,12-dimethylbenz(a)anthracene can induce ecotropic virus expression in approximately 95% of treated DBA/2 mice. Previous experiments involving DNA transfection and marker rescue analysis of molecularly cloned Emv-3 DNA suggested that Emv-3 carries a small defect(s) in the gag gene, not detectable by restriction enzyme mapping, that inhibits virus expression in vivo and in vitro. Using a combination of approaches, including DNA sequencing, peptide mapping, and metabolic labeling of cells with [3H]myristate, we have demonstrated that the defect in Emv-3 most likely results from a single nucleotide substitution within the gene for p15gag that inhibits myristylation of the Pr65gag N terminus. Myristylation of Pr65gag is thought to be required for this protein to associate with the plasma membrane and is essential for virus particle formation. These results provide a conceptual framework for understanding how Emv-3 expression is regulated during development and after chemical induction.

Identification and characterization of c-raf phosphoproteins in transformed murine cells

Protein products of the c-raf gene were detected and characterized in two transformed murine cells lines by immunoprecipitation analysis with raf-specific sera. Both proteins reacted with an antiserum directed to the carboxyl terminus of the c-raf coding region. The p48raf (Mr48,000) phosphoprotein was found in a cell line transformed by an LTR-activated c-raf gene (Mueller & Mueller, 1984). It was found to be phosphorylated on serine and threonine residues and became phosphorylated in immunoprecipitates when supplied with [gamma-32]ATP. In contrast, P74raf, which was detected into a spontaneously transformed 3T3 (R+/Cl 3) cell line and may represent the full-length gene product of c-raf, appeared to incorporate [32P]PO4 less efficiently in vivo and exhibited a barely detectable associated kinase activity in only half of the experiments. The p48raf is a transforming protein which, like P75gag-raf, lacks the amino-terminal region of the c-raf coding region. P74raf, which retains the amino-terminal region, differs from p48raf in its phosphorylation characteristics and may not be a transforming protein. These data are consistent with a model in which lack of amino-terminal sequences in the c-raf gene product p48raf may, in and of itself, suffice to make it a transforming protein.

Hydroxylamine-stable covalent linkage of myristic acid in G0 alpha, a guanine nucleotide-binding protein of bovine brain

G0 alpha, a guanine nucleotide-binding protein with a strong homology to the G1 alpha and Gs alpha regulatory proteins of adenylate cyclase, is shown to contain myristic acid. The attachment of myristate to the protein is stable to hydroxylamine treatment, and since the amino-terminal sequence of G0 alpha is typical of proteins with amino-terminal myristate, the inference is strong that G0 alpha is also myristylated at its amino-terminal glycine.

Myristylation site in Pr65gag is essential for virus particle formation by Moloney murine leukemia virus

It was previously reported that the gag proteins of mammalian type C retroviruses are modified by the addition of myristate to the N-terminal glycine residue. We have performed oligonucleotide-directed mutagenesis to change this glycine codon in the Moloney murine leukemia virus genome to an alanine codon and also to specifically delete the glycine codon. Upon transfection into mammalian cells, these mutant genomes direct the synthesis of gag proteins, but these proteins are not myristylated. The mutants do not form virus particles or any recognizable virus-specific structures visible in thin sections with the electron microscope. Further, the mutant gag proteins appear to remain in the cytosol, whereas the wild type is found principally in particulate fractions of the cell. The results are consistent with the theory that myristate is required for the association of the gag protein with the plasma membrane and that this association is necessary for virus assembly.

Detection of the myristylated gag-raf transforming protein with raf-specific antipeptide sera

The post-translational modifications of the gag-raf fusion proteins of the 3611 murine sarcoma virus (MSV) have been examined by inhibiting glycosylation with tunicamycin and by in vivo labeling with [3H]myristic acid. The results show that P75gag-raf is myristylated but not glycosylated and that P90gag-raf is glycosylated but not myristylated (and is now termed gP90gag-raf). gP90gag-raf expression appeared to become lost during passage of the transformed cells, and consequently does not appear to be necessary for the maintenance of transformation. raf-specific sera for detecting gag-raf fusion proteins have been obtained from synthetic peptides made from different regions of the predicted v-raf sequence. Immunoprecipitation of P75gag-raf with raf-specific sera directly confirmed the deduced v-raf sequence. The fact that P75gag-raf is both myristylated and precipitated by antiserum to a predicted carboxyl-terminal peptide of the v-raf gene established that the mature protein represents the entire coding region. The gP90gag-raf thus appears to be a glycosylated form of P75gag-raf specified by the gag sequences of the fusion protein, in analogy with Pr65gag and gPr80gag of murine leukemia viruses. Antiserum to the carboxyl-terminal P75gag-raf peptide was the most efficient in immunoprecipitation, and will be useful for detecting the product of the c-raf gene.

Infection of immune mast cells by Harvey sarcoma virus: immortalization without loss of requirement for interleukin-3

Cells from adult mouse spleens were cultured in WEHI-3 cell-conditioned medium, which contains the lymphokine interleukin-3 (IL-3). Under these conditions, cells grow well for 4 to 8 weeks; the cultures contain a variety of cell types for the first 1 to 2 weeks but are subsequently composed largely of immune mast cells. We found that infection of these cultures with Harvey sarcoma virus (HaSV) profoundly enhanced the growth potential of the cells, resulting in the reproducible isolation of long-term cell lines. These HaSV-infected cells appeared to be phenotypically identical to the immune mast cells found in uninfected cultures as determined by biochemical, immunological, and cytological tests. Although the cells expressed protein p21Ha-ras at levels similar to those in HaSV-transformed fibroblasts, they continued to require IL-3 for growth in vitro. Similar IL-3-dependent, long-term mast cell lines were also cultured from the enlarged spleens present in HaSV-infected mice. These results suggest that high-level expression of an activated Ha-ras oncogene enhances growth in these cells, perhaps by stimulating the progression of the cells into S, without affecting differentiation or altering the requirements for normal growth factor.

Amino terminal myristylation of the protein kinase p60src, a retroviral transforming protein

The transforming protein of Rous sarcoma virus, p60src, was shown to be acylated at its amino terminus with the long-chain fatty acid myristic acid by isolation of a tryptic peptide with the following structure: myristylglycylserylseryllysine. The occurrence of this unusual posttranslational modification in the cyclic adenosine monophosphate-dependent protein kinase and in several transforming protein kinases of mammalian retroviruses suggests that myristylation of the amino terminal glycyl residue may be critical for the function of certain proteins related to cell transformation and growth control.

The envelope proteins of bovine leukemia virus: purification and sequence analysis

Two proteins, termed gp60 and p30, have been purified to homogeneity from bovine leukemia virus (BLV) using controlled pore glass and reverse-phase liquid chromatography (RPLC). gp60 was shown to be a glycoprotein by identification of glucosamine on the amino acid analyzer. Antiserum prepared to gp60 recognized in addition to gp60 a 52,000-Da polypeptide in some virus preparations, but did not cross-react with p30. The amino and carboxyl termini of gp60 were found to be tryptophan and arginine, respectively, and a 38-residue amino-terminal sequence of gp60 (NH2TrpArgXSerLeuSerLeuGlyAsnGlnGlnTrpMetThrAlaTyrAsnGlnGluAlaLys PheSerIleSerIleAspGlnIleLeuGluAlaHisAsnGlnSerProPhe-) was obtained. A 12-residue amino-terminal sequence for p30 (NH2SerProValAlaAlaLeuThrLeuGlySerAlaLeu) was also obtained. The p30 sequence showed substantial homology to the transmembrane proteins of both types B and C retroviruses and also to a deduced sequence of the 3' region of the env gene of human T-cell leukemia virus. From these results and from elution behavior of these proteins on RPLC, it was concluded that gp60 and p30 are the BLV env gene-encoded surface glycoprotein and transmembrane protein, respectively.

In vivo modification of retroviral gag gene-encoded polyproteins by myristic acid

It has recently been shown by mass spectral analysis (Henderson et al., Proc. Natl. Acad. Sci. U.S.A. 80:339-343, 1983) that the p15gag protein of murine leukemia viruses contains a novel post-translational modification, an amino-terminal myristyl (tetradecanoyl) amide. In this report we show that p15gag is the only structural protein to contain this fatty acid. In addition, the gag precursor polyproteins of type B, C, and D retroviruses have been examined for the presence of myristic acid by metabolic labeling and immunoprecipitation studies. In a panel of mammalian type C retroviruses we found that the precursor polyprotein Pr65gag homologs, but not the glycosylated forms (gPr80gag homologs), were specifically labeled after a 5-min incubation of infected cells with [3H]myristic acid. The gag precursor polyprotein was also labeled in mouse mammary tumor virus and in Mason-Pfizer monkey virus, but Pr76gag of Rous sarcoma virus failed to incorporate [3H]myristate. Under similar conditions, [3H]palmitate was not found to be incorporated into any viral gag proteins. Thus, myristylation appears to be a common feature of mammalian type B, C, and D retroviruses but not of avian retroviruses.

Structure of glycosylated and unglycosylated gag polyproteins of Rauscher murine leukemia virus: carbohydrate attachment sites

The structural relationships among the gag polyproteins Pr65gag, Pr75gag, and gPr80gag of Rauscher murine leukemia virus were studied by endoglycosidase H digestion and formic acid cleavage. Fragments were identified by precipitation with specific antisera to constituent virion structural proteins followed by one-dimensional mapping. Endoglycosidase H reduced the size of gPr80gag to that of Pr75gag. By comparing fragments of gPr80gag and the apoprotein Pr75gag, the former was shown to contain two mannose-rich oligosaccharide units. By comparing fragments of Pr65gag and Pr75gag, the latter was shown to differ from Pr65gag at the amino terminus by the presence of a leader peptide approximately 7,000 daltons in size. The internal and carboxyl-terminal peptides of the two unglycosylated polyproteins were not detectably different. The location of the two N-linked carbohydrate chains in gPr80gag has been specified. One occurs in the carboxyl-terminal half of the polyprotein at asparagine177 of the p30 sequence and the other is found in a 23,000-dalton fragment located in the amino-terminal region of gPr80gag and containing the additional amino acid sequences not found in Pr65gag plus a substantial portion of p15.

Post-translational modification of Rauscher leukemia virus precursor polyproteins encoded by the gag gene

Post-translational modifications of retrovirus gag gene-encoded polyproteins include proteolytic cleavage, phosphorylation, and glycosylation. To study the sequence of these events, we labeled JLS-V9 cells chronically infected with Rauscher murine leukemia virus in pulse-chase experiments with the radioactive precursors [35S]methionine, [14C]mannose, [3H]glucosamine, and [32P]phosphate. Newly synthesized gag polyproteins which incorporated label, and the modified products derived from them, were identified by immunoprecipitation of cell lysates with anti-p30 rabbit serum, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Pulse-chase experiments were carried out in the presence as well as in the absence of tunicamycin, an inhibitor of glycosylation. Among the three major polyproteins synthesized in the absence of tunicamycin, two were found to be glycosylated but not phosphorylated. These were designated gPr80gag and gP94gag. Both shared identical [35S]methionine peptides with Pr65gag and p30. Of the two nonglycosylated precursors, Pr65gag and Pr75gag, only Pr65gag was found to be detectably phosphorylated, and Pr75gag could be readily identified only when glycosylation was inhibited. On the basis of these results, a scheme for the post-translational modification of gag polyproteins is proposed. According to this scheme the gag gene-encoded polyproteins are processed from a common precursor, Pr75gag, by two divergent pathways: one leading through the intermediate Pr65gag to internal virion components via cleavage and phosphorylation and the other via tunicamycin-sensitive mannosylation to the intermediate gPr80gag, which is further glycosylated to yield cell surface polyprotein gP94gag.