Bioneutralization capacity of the antibodies generated in women by the beta subunit of human chorionic gonadotropin (beta hCG) and beta hCG associated with the alpha subunit of ovine luteinizing hormone linked to carriers

Data is presented on the bioneutralization capacity per unit immunoactivity of 30 serum samples of women immunized with the beta-subunit of human chorionic gonadotropin (beta-hCG) or beta hCG associated noncovalently with the alpha-subunit of ovine luteinizing hormone (alpha-oLH), to form a heterospecies dimer (HSD), which were linked to carriers. The bioassays utilized were inhibition of radioiodinated hCG binding to rat testicular receptors in vitro and the inhibition of hCG induced testosterone production in mice. In both assays, antisera of women immunized with the HSD had a bioactivity to immunoactivity ratio that was about 25% higher, on an average, than antisera of women immunized with beta-hCG, suggesting a better bioneutralization capacity of sera raised by the HSD in women.

Impact of seasonal variation on Leishmania donovani infection in hamsters

The impact of seasonal variation on the course of L. donovani infection in hamsters was investigated. Though the animals were maintained in controlled climatic conditions (25 degrees C +/- 2), parasites exhibited seasonal rhythm. During summer (April-July) when the atmospheric temperature ranged from 20.5 degrees C to 41.8 degrees C, the parasite load from an inoculum of 1 x 10(7) amastigotes/animal was found to be less than 1 to 9 per 100 cell nuclei (based on spleen biopsy) on day 25-35 post infection. An escalation in count was observed from August onwards, which reached the peak (approximately 30/100 cell nuclei) in February-March (temp. range 11.3 degrees C to 31.4 degrees C). The multiplication rate monitored 15 days after the initial assessment also showed a similar pattern. The secondary organs examined showed no parasites. The study revealed that despite the non-involvement of the vector in experimental infection in hamster, the parasites retained its periodic character as in man, corresponding to cyclicity of vector.

Characterization of an HIV-1 point mutant blocked in envelope glycoprotein cleavage

The envelope proteins of retroviruses are derived from a polypeptide precursor protein by cleavage adjacent to a cluster of basic amino acids. Site-specific mutagenesis was used to construct a mutant of the human immunodeficiency virus type 1 (HIV-1) in which the arginine residue at the carboxy-terminus of the gp120 was changed to a threonine residue. This single substitution was sufficient to abolish all detectable cleavage of the gp160 envelope precursor polypeptide as well as virus infectivity. The gp160 was produced in normal quantities from a biologically active clone of the mutant virus after transfection into cos-1 cells. The mutant gp160 contained N-linked oligosaccharide chains with mannose-rich cores similar to those of the gp160 produced by the wild-type clone. Immunofluorescence assays showed that gp160 was transported to the surface of transfected CD4+ HeLa cells. No envelope proteins of known size could be detected in the media of cells transfected with the mutant virus, suggesting that functional virions were not formed. Binding of the mutant gp160 to the CD4 receptor molecule was unimpaired. Despite this and the presence of gp160 on the cell surface, neither growth of mutant-transfected CD4+ HeLa cells nor cocultivation of transfected cos-1 cells with H9 cells resulted in significant syncytium formation. The data indicate that the carboxy-terminal arginine residue of HIV-1 gp120 is necessary for envelope protein cleavage and suggest cleavage is important in the virus life cycle in both functional virus release and membrane fusion.

Monoclonal antibodies to HTLV-III451 gp41: delineation of an immunoreactive conserved epitope in the transmembrane region of divergent isolates of HIV-1

We report on the development of monoclonal antibodies directed against the transmembrane portion of the envelope of HTLV-III451 gp41. One of these monoclonal antibodies, designated M71/2B4, was found to cross-react with transmembrane proteins from other independent isolates of HIV-1, namely IIIB, MN, and RF. Thus, this monoclonal antibody identifies an epitope located in a region of gp41 that is conserved among all these isolates. To identify this conserved region a series of E. coli recombinant proteins were screened in immunoblot with M71/2B4. From these results the epitope recognized by this antibody appears to map at the amino terminus of gp41, in the region indicated between the cleavage site with gp120 (aa 508) and the HindIII site (aa647).

Lectin typing of Pseudomonas aeruginosa strains of different serogroups, Habs and Fisher types

Sixteen Habs and three Fisher types of Pseudomonas aeruginosa were typed with lectins of know specificity resulting from their interaction with bacterial cell surface carbohydrates as evidenced by agglutination-inhibition assay with simple carbohydrates. Lipopolysaccharides of few strains of Pseudomonas are precipitated with different lectins and the results are corroborated by those of agglutination suggesting that Pseudomonas aeruginosa can be characterized intraspecifically by lectins.

Effect of cadmium on lipid peroxidation and antioxidant enzymes in undernourished weanling rat brain

The effect of early postnatal cadmium exposure on lipid peroxidation and antioxidant enzymes in undernourished weanling rat brain has been studied. The results suggest that undernutrition makes the weanling rat brain more susceptible to the neurotoxic effects of cadmium. Cadmium at a low dose of 1 mg/kg body weight did not produce any changes in lipid peroxidation and antioxidant enzymes in normal weanling rat brain, but caused a significant increase in lipid peroxidation and markedly decreased the activities of antioxidant enzymes like glutathione peroxidase, superoxide dismutase and catalase when subjected to undernutrition.

Role of oligosaccharides in the processing and maturation of envelope glycoproteins of human immunodeficiency virus type 1

The processing and maturation of envelope glycoproteins of human immunodeficiency virus type 1 (HIV-1) were studied in infected cells treated with inhibitors of oligosaccharide processing. In MOLT-3 cells chronically infected with HIV-1 (strain HTLV-IIIB), tunicamycin severely inhibited the glycosylation of envelope proteins. Deoxynojirimycin, an inhibitor of glucosidase I in the rough endoplasmic reticulum, inhibited the proteolytic processing of gp160, whereas no such effect was noted with either deoxymannojirimycin or swainsonine, inhibitors of mannosidase I and II, respectively, in the Golgi complex. The processed gp120 and gp41 synthesized in the presence of deoxymannojirimycin were found to contain mannose-rich oligosaccharide cores as evidenced by their susceptibility to endoglycosidase H digestion. The formation of syncytia normally observed when CEM cells are cocultured with HIV-1-infected cells was markedly inhibited in the presence of deoxynojirimycin, but such inhibition was not observed in cells treated with deoxymannojirimycin or swainsonine. The infectivity of virions released from MOLT-3/HTLV-IIIB cells treated with deoxynojirimycin or deoxymannojirimycin was significantly lower than the infectivity of virions released from untreated cells. On the other hand, treatment with swainsonine did not affect the infectivity of the progeny virus. These results suggest that the proteolytic processing of gp160 takes place in infected cells when the glycoprotein has mannose-rich oligosaccharide structures. Trimming of glucose residues and the primary trimming of mannose residues are necessary for the release of infectious virus.

Primer-mediated enzymatic amplification of cytomegalovirus (CMV) DNA. Application to the early diagnosis of CMV infection in marrow transplant recipients

A nucleic acid amplification procedure, the polymerase chain reaction (PCR), has been used to establish a diagnostic assay for the identification of cytomegalovirus (CMV) immediate-early sequences in clinical specimens. Preliminary testing against virus-infected cell cultures indicated that the PCR assay was highly CMV-specific, recognizing both wild-type and laboratory strains of CMV. There was no cross-reactivity with human DNA or with DNA from other herpes viruses. The sensitivity of the assay, using cloned CMV AD169 Eco RI fragment-J as template, was 1 viral genome per 40,000 cells. In a prospective study of CMV infection in bone marrow transplant recipients, the PCR assay correctly identified four patients with confirmed CMV infection. In three of these patients who were followed longitudinally, correlation of DNA reactivity with CMV culture and CMV antibody status over time indicated that DNA was the most sensitive marker for the diagnosis of CMV infection.

Processing and secretion of envelope glycoproteins of human immunodeficiency virus type 1 in the presence of trimming glucosidase inhibitor deoxynojirimycin

The processing and secretion of the envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) were studied in chronically infected cells treated with the trimming glucosidase inhibitor deoxynojirimycin (DNM). In Molt3 cells infected with human T-lymphotropic virus type III (HTLV-IIIB), DNM inhibited the intracellular proteolytic processing of gp160 to gp120 and gp41. A clone of the HUT78 cell line called 6D5, when chronically infected with the HIV-1 isolate HTLV-III451 was shown to release both gp160 and gp120 into the culture medium. The secretion of envelope glycoproteins from these infected cells was not inhibited by DNM treatment. The secreted proteins had higher molecular weights than gp160 and gp120 from cultures not treated with DNM, presumably due to the presence of unprocessed carbohydrate residues on the polypeptide chain. These secreted glycoproteins from DNM-treated cells exhibited specific interaction with the CD4 molecule on the surface of target cells. However, the syncytium formation induced by HIV-1-infected cells on CD4+ cells was significantly inhibited in the presence of the glucosidase inhibitor. The minimal cytotoxicity of the DNM coupled with its strong inhibitory effect on the cell-to-cell spread of the virus suggest that it may be potentially useful in antiviral drug therapy of HIV-1 infection.

Processing of the structural proteins of human immunodeficiency virus type 1 in the presence of monensin and cerulenin

The synthesis and processing of structural proteins of human immunodeficiency virus type 1 (HIV-1) were studied in infected cells treated with monensin and cerulenin. In MOLT-3 cells chronically infected with HTLV-IIIB, monensin inhibited the proteolytic cleavage of the env-coded polyprotein gp160 to gp120, leading to the accumulation of the precursor gp160. The formation of syncytia normally observed when CEM cells are cocultivated with HIV-1-infected MOLT-3 cells was significantly inhibited in the presence of monensin. The effect of the ionophore on the culture was reversible, as withdrawal of monensin from the medium restored the ability of the cells to form syncytia with CEM cells and led to the resumption of the processing of gp160 to gp120. Monensin did not affect the synthesis and processing of gag-coded proteins and regulatory proteins. Cerulenin, an inhibitor of de novo fatty acid biosynthesis, inhibited the myristoylation and the proteolytic cleavage of the gag-coded polyprotein Pr53gag to p24 but did not affect the processing of gp160. However, use for monensin and cerulenin as antiviral agents for treatment of HIV-1 infection cannot be foreseen because of the pronounced in vitro toxicity observed.

A unique human immunodeficiency virus culture secreting soluble gp160

A clone of the HUT78 cell line, chronically infected with the HIV-1 isolate HTLV-III451, has been demonstrated to secrete unprocessed HIV-1 envelope precursor protein gp160 as well as mature gp120. Further, when grown in serum-free defined medium these cells released approximately five times the amount of virus compared with cultures in normal medium. These proteins corresponded in their immunologic reactivities with the respective envelope proteins of the HTLV-IIIB isolate. They formed high-affinity soluble complexes with the CD4 antigen and inhibited the syncytium formation induced by HTLV-IIIB on CD4-positive cells. This is the first description of an HIV-1 culture system capable of shedding into the medium native gp160 that is soluble in the absence of detergents.

Antigenicity, function, and conformation of synthetic oligopeptides corresponding to amino-terminal sequences of wild-type and mutant matrix proteins of vesicular stomatitis virus

The matrix (M) protein of vesicular stomatitis virus (VSV) has a major antigenic determinant (epitope 1) that maps to a region extending from amino acids 19 through 43 and transcription-inhibition activity that maps to the first 43 N-terminal amino acids (J.R. Ogden, R. Pal, and R. R. Wagner, J. Virol. 58:860-868, 1986). The M protein of temperature-sensitive mutant tsO23(III) is devoid of epitope 1 and transcription-inhibition activity and substitutes glutamic acid for glycine at amino acid 21 as well as having amino acid substitutions at positions 111 and 227 (K. Morita, R. Vanderoef, and J. Lenard, J. Virol. 61:256-263, 1987). We undertook to map more precisely epitope 1 and the transcription-inhibition region of VSV M protein by means of synthetic oligopeptides generated by an automated solid-phase protein synthesizer. A pentadecapeptide designated PI(wt, Gly21), corresponding to amino acids 17 to 31 of wild-type (wt) M protein, strongly bound monoclonal antibody MAb2 (directed to epitope 1); however, an analogous pentadecapeptide with glutamic acid substituted for glycine at position 21, designated PII(tsO23, Glu21), completely failed to recognize MAb2. Polyclonal antibody raised in rabbits immunized with PI(wt, Gly21) reacted strongly with wt M protein, the homologous pentadecapeptide, and, to a lesser extent, PII(tsO23, Glu21). Anti-PII(tsO23, Glu21) failed to recognize PI(wt, Gly21) or wt M protein. Anti-PI(wt, Gly21) competed efficiently for binding of MAb2 to wt M protein and was as effective as MAb2 in reversing inhibition of VSV transcription by wt M protein. Neither PI(wt, Gly21) nor PII(tsO23, Glu21) exhibited any ability to inhibit VSV transcription. However, a lysine-rich oligopeptide, PII(Met1-Leu20), corresponding to the first 20 N-terminal amino acids of wt M protein, and polylysine itself did inhibit VSV transcription, albeit much less efficiently than native wt M protein. Monospecific polyclonal antibody directed to the 20-mer oligopeptide PIII(Met1-Leu20) reversed transcription inhibition by M protein in a dose-dependent manner almost identical to that of anti-PI(wt, Gly21) and epitope 1-specific MAb2. Examination by circular dichroism spectropolarimetry revealed significant differences in the conformation of the two pentadecapeptides attributable to the Gly in equilibrium Glu amino acid substitution at position 21.

Pyrene phospholipid as a biological fluorescent probe for studying fusion of virus membrane with liposomes

We are using fluorescent endogenous phospholipids in virus membranes to study the factors that promote fusion on interaction with receptor membranes. To this end, vesicular stomatitis virus (VSV) grown in baby hamster kidney (BHK-21) cells was biologically labeled with fluorescent lipids, primarily phosphatidylcholine and phosphatidylethanolamine, derived from pyrene fatty acids. The pyrene lipids present in the virions showed a fluorescence spectrum typical of pyrene with an intense monomer and a broad excimer. Interaction of pyrene lipid labeled VSV with serum lipoproteins led to a spontaneous fast transfer of the small amount of pyrene fatty acids present in the envelope (t1/2 less than or equal to 7 min), followed by a considerably slower transfer of pyrene phospholipids from the membrane of the virions (t1/2 greater than or equal to 12 h). Incubation of pyrene phospholipid labeled VSV with phosphatidylserine small unilamellar vesicles resulted in fusion at low pH (pH 5.0) as measured by the change in the excimer/monomer fluorescence intensity ratio. Fusion kinetics was rapid, reaching a plateau after 4 min at pH 5.0 and 37 degrees C. Only negligible fusion was noted at neutral pH or at 4 degrees C. Fully infectious virions labeled biologically with fluorescent lipids provide a useful tool for studying mechanisms of cell-virus interactions and neutralization of viral infectivity by specific monoclonal antibodies reactive with viral membrane glycoprotein.

Hemagglutination patterns of Pseudomonas aeruginosa strains of different serogroups, Habs and Fisher types

Pseudomonas aeruginosa strains of sixteen Habs and three Fisher types were examined for their hemagglutination activity using vertebrate erythrocytes including human ones. Their carbohydrate-binding specificity as determined by hemagglutination-inhibition suggests a possible method of their purification. This study also indicates the possibility of an occurrence of multiple lectins of different specificity.

Functional and antigenic domains of the matrix (M1) protein of influenza A virus

The membrane- and ribonucleocapsid (RNP)-binding domains of the matrix (M1) protein of influenza A virus (WSN strain) were partially mapped and characterized by reactivity with monoclonal antibodies (MAb) as well as by proteolytic cleavages and amino acid sequencing of the resulting peptides. Of two peptides formed by formic acid hydrolysis, a 9-kilodalton fragment at the amino-terminal third of the M1 protein was recognized by MAb M2-1C6 (to epitope 1), and a 15-kilodalton fragment at the carboxy-terminal two-thirds was recognized by MAb 289/4 (to epitope 2). Partial cleavage by staphylococcal V8 protease gave rise to a 16-kilodalton peptide, mapping to amino acid 8, which was recognized by MAbs to all three epitopes but rather weakly by MAb 904/6 to epitope 3. These studies suggest that epitope 1 of the M1 protein resides between amino acids 8 and 89, whereas epitopes 2 and possibly 3 are located between amino acids 89 and 141 or somewhat more carboxy distal. The intact M1 protein and its N-terminal 9- and 10-kilodalton peptides generated by formic acid or V8 protease cleavage, respectively, reconstituted with dipalmitoylphosphatidylcholine vesicles, but these N-terminal peptides had little effect on in vitro transcription of the RNP core. In sharp contrast, both intact M1 protein and the C-terminal 15-kilodalton formic acid fragment were able to inhibit viral transcription markedly. Moreover, MAb 289/4 (to epitope 2) reversed this inhibited transcription significantly. These studies suggest that the lipid-binding domain of the M1 protein is located within the amino-terminal third, whereas the site involved in the interaction of the M1 protein with RNP cores is located within the carboxy-terminal two-thirds.

Effect of the vesicular stomatitis virus matrix protein on the lateral organization of lipid bilayers containing phosphatidylglycerol: use of fluorescent phospholipid analogues

In order to investigate the mode of interaction of peripheral membrane proteins with the lipid bilayer, the basic (pI approximately 9.1) matrix (M) protein of vesicular stomatitis virus was reconstituted with small unilamellar vesicles (SUV) containing phospholipids with acidic head groups. The lateral organization of lipids in such reconstituted membranes was probed by fluorescent phospholipid analogues labeled with pyrene fatty acids. The excimer/monomer (E/M) fluorescence intensity ratios of the intrinsic pyrene phospholipid probes were measured at various temperatures in M protein reconstituted SUV composed of 50 mol % each of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG). The M protein showed relatively small effects on the E/M ratio either in the gel or in the liquid-crystalline phase. However, during the gel to liquid-crystalline phase transition, the M protein induced a large increase in the E/M ratio due to phase separation of lipids into a neutral DPPC-rich phase and DPPG domains presumably bound to M protein. Similar phase separation of bilayer lipids was also observed in the M protein reconstituted with mixed lipid vesicles containing one low-melting lipid component (1-palmitoyl-2-oleoylphosphatidylcholine or 1-palmitoyl-2-oleoylphosphatidylglycerol) or a low mole percent of cholesterol. The self-quenching of 4-nitro-2,1,3-benzoxadiazole (NBD) fluorescence, as a measure of lipid clustering in the bilayer, was also studied in M protein reconstituted DPPC-DPPG vesicles containing 5 mol % NBD-phosphatidylethanolamine (NBD-PE). The quenching of NBD-PE was enhanced at least 2-fold in M protein reconstituted vesicles at temperatures within or below the phase transition.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of the fluorophore 4-heptadecyl-7-hydroxycoumarin: a probe for the head-group region of lipid bilayers and biological membranes

The fluorophore 4-heptadecyl-7-hydroxycoumarin was used as a probe to study the properties of phospholipid bilayers at the lipid-water interface. To this end, the steady-state fluorescence anisotropy, the differential polarized phase fluorometry, and the emission lifetime of the fluorophore were measured in isotropic viscous medium, in lipid vesicles, and in the membrane of vesicular stomatitis virus. In the isotropic medium (glycerol), the probe showed an increase in the steady-state fluorescence anisotropy with a decrease in temperature, but the emission lifetime was unaffected by the change in temperature. In glycerol, the observed and predicted values for maximum differential tangents of the probe were identical, indicating that in isotropic medium 4-heptadecyl-7-hydroxycoumarin is a free rotator. Nuclear magnetic resonance and differential scanning calorimetric studies with lipid vesicles containing 1-2 mol % of the fluorophore indicated that the packaging density of the choline head groups was affected in the presence of the probe with almost no effect on the fatty acyl chains. The fluorophore partitioned equally well in the gel and liquid-crystalline phase of the lipids in the membrane, and the phase transition of the bilayer lipids was reflected in the steady-state fluorescence anisotropy of the probe. The presence of cholesterol in the lipid vesicles had a relatively small effect on the dynamics of lipids in the liquid-crystalline state, but a significant disordering effect was noted in the gel state. One of the most favorable properties of the probe is that its emission lifetime was unaffected by the physical state of the lipids or by the temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid and protein contributions to the membrane surface potential of vesicular stomatitis virus probed by a fluorescent pH indicator, 4-heptadecyl-7-hydroxycoumarin

The surface potential of membranes of vesicular stomatitis virus and liposomes was determined by shift of ionization over a wide pH range of the membrane-inserted fluorophore, 4-heptadecyl-7-hydroxycoumarin. Incorporation into sonicated vesicles of negatively charged phosphatidylserine markedly increased the surface potential of uncharged phosphatidylcholine, but no significant effect on surface potential was produced by polar but uncharged glucocerebroside incorporated in phosphatidylcholine vesicles. The membrane of vesicular stomatitis virus was found to have a moderately high surface potential. Contributing to this viral membrane surface potential were glycoprotein spikes and phospholipid headgroups as determined by lowered charge after treatment of intact virions with thermolysin to remove glycoprotein or phospholipase C to remove phospholipid headgroups. The role of viral glycoprotein was confirmed by demonstrating increased surface charge of vesicles reconstituted with both viral glycoprotein and lipids compared with vesicles reconstituted with viral lipids alone. An unexpected finding was the large contribution to surface potential of cholesterol present in viral membrane. Increasing cholesterol concentration in virions by interaction with cholesterol-complexed serum lipoproteins resulted in a marked decrease in surface potential, whereas 75% depletion of virion cholesterol by interaction with sphingomyelin-complexed serum lipoproteins resulted in a significant increase in virion membrane surface potential. Although removal of glycoprotein spikes or depletion of cholesterol causes reduction in infectivity of vesicular stomatitis virus, no direct correlation could be found between alteration in surface charge and infectivity.

Thiomethylation and thiohydroxylation--a new pathway of metabolism of heterocyclic compounds

1. G.l.c.--mass spectral analysis of t.l.c. fractions of urine samples of patients treated with 5-(2-chloroethyl)-4-methylthiazole (clomethiazole), has revealed two minor metabolites, each with two sulphur atoms. 2. Their structures were found to be 2-methylthio-clomethiazole and 5-acetyl-4-methyl-2-mercapto-thiazole, formed by thiomethylation and thiohydroxylation, respectively, of the original compound. 3. The structures of six other minor metabolites resulting from side-chain degradation have been elucidated. 4. The occurrence of metabolites with substituents at position 2 of the heterocyclic nucleus is assumed to be initiated by oxidative attack at the nitrogen, followed by nucleophilic substitution in position 2.

Pardaxin, a hydrophobic toxin of the Red Sea flatfish, disassembles the intact membrane of vesicular stomatitis virus

Reaction of vesicular stomatitis virus with pardaxin, the hydrophobic toxin of the Red Sea flatfish, resulted in a profound morphological change of many virions and dissociation of their membrane and nucleocapsid into components readily separable by density gradient centrifugation. The basic matrix protein and acidic pardaxin segregated largely with the high density nucleocapsid. The dissociated virion membrane formed lipoprotein vesicles which retained glycoprotein spikes and a certain amount of N protein but no appreciable amounts of other nucleocapsid proteins and little if any RNA. Iodination of the tyrosine residue of the glycoprotein tail fragment provided supporting evidence that the COOH terminus of the glycoprotein extends beyond the inner layer of the membrane into the interior of the virion. These data indicate that pardaxin may serve as a probe for studying the organization of viral membranes, and, hopefully, other biological membranes.

Transcription of vesicular stomatitis virus activated by pardaxin, a fish toxin that permeabilizes the virion membrane

The toxic protein, Pardaxin, of the Red Sea flatfish Pardachirus marmoratus readily induced transcription of vesicular stomatitis virus by making the virion membrane permeable to nucleoside triphosphates in the absence of nonionic detergents. Virion transcription was activated over a wide range of Pardaxin concentrations, but at optimal concentrations, the rate of transcription exceeded that induced by Triton X-100. The inhibitory effect of M protein was manifested for both Pardaxin-induced and Triton-induced transcription at high concentrations of vesicular stomatitis virions; however, unlike the Triton-induced reaction, the inhibitory effect of M protein was not reversed by polyglutamic acid added to the Pardaxin-induced transcription reaction. We propose that activation of virion transcription by Pardaxin resembles more closely intracellular transcription initiated by virion penetration than does detergent-activated transcription of vesicular stomatitis virus.

Fluorescence studies of dipalmitoylphosphatidylcholine vesicles reconstituted with the glycoprotein of vesicular stomatitis virus

The vesicular stomatitis virus glycoprotein (G) was reconstituted into dipalmitoylphosphatidylcholine (DPPC) vesicles by detergent dialysis. The DPPC gel to liquid-crystalline phase transition of the DPPC-G protein vesicles was monitored by the fluorescence anisotrophy of trans-paranaric acid, 16-(9-anthroyloxy)palmitoylglucocerebroside, 1,6-diphenyl-1,3,5-hexatriene, and 4-heptadecyl-7-hydroxycoumarin. The DPPC transition temperature measured by all four fluorescent probes was lowered in the presence of the G protein and the DPPC gel state was disordered by the G protein as evidenced by a decreased fluorescence anisotropy for all four probes below the phase-transition temperature. A possible ordering of the DPPC liquid-crystalline state by the G protein was indicated by an increased anisotropy of trans-paranaric acid and 16-(9-anthroyloxy)palmitoylglucocerebroside in the liquid-crystalline state of DPPC-G protein vesicles. The G protein in addition affected the ionization of the 4-heptadecyl-7-hydroxycoumarin in lipid vesicles, increasing the apparent pK of the probe from 9.05 to 9.45.

Fluorescence anisotropy of a fatty acid covalently linked in vivo to the glycoprotein of vesicular stomatitis virus

The covalently-attached fatty acid of the membrane glycoprotein (G) of vesicular stomatitis virus was fluorescently labeled biologically by isolating vesicular stomatitis virus from infected baby hamster kidney clone 21 cells that had been grown in the presence of 16(9-anthroyloxy)palmitate. The fluorescent labeling was specific for the G protein; the other viral membrane protein, the matrix (M) protein, was not labeled. Steady state fluorescence anisotropy of the 16(9-anthroyloxy)palmitate-labeled G protein reconstituted into dipalmitoylphosphatidylcholine vesicles indicated that the fatty acid attached to G protein is located in a dipalmitoylphosphatidylcholine domain that does not undergo the gel to liquid-crystalline phase transition.

Depletion and exchange of cholesterol from the membrane of vesicular stomatitis virus by interaction with serum lipoproteins or poly(vinylpyrrolidone) complexed with bovine serum albumin

Cholesterol was depleted from the membrane of vesicular stomatitis virus by exposing virion suspensions to serum lipoproteins enriched with phospholipids. Unlike the reaction of virions with phospholipid vesicle, nonspecific adherence of lipoproteins and exogenous lipids to the envelope of the virus was found to be minimal. The extent of cholesterol depletion was dependent upon the type of phospholipid complexed with interacting lipoprotein; sphingomyelin and dipalmitoyllecithin were found to be highly effective depleters of cholesterol compared to egg phosphatidylcholine, phosphatidylethanolamine, or phosphatidylserine. Similar depletion of cholesterol from the virion membrane was also observed when vesicular stomatitis virus was exposed to a complex of poly(vinylpyrrolidone) and bovine serum albumin coated with egg phosphatidylcholine or dioleoylphosphatidylcholine. Cholesterol depletion was found to alter the morphology but not the membrane integrity of the virus. Directly correlated with depletion of cholesterol was a substantial loss in the anisotropy of the viral membrane as determined by fluorescence depolarization of the lipophilic probe 1,6-diphenyl-1,3,5-hexatriene. Interaction with poly(vinylpyrrolidone) complexed with albumin, phosphatidylcholine, and cholesterol resulted in exchange of cholesterol from the virion membrane which following biphasic kinetics with a rapid and a slow phase; these data indicate that 75-85% of viral membrane cholesterol is present in the outer monolayer, and 15-25% is located in the inner monolayer. Depletion of cholesterol from the virion membrane resulted in a significant drop in the infectivity of the virus as measured by plating efficiency on L-cell monolayers. Such an effect was not observed when virion cholesterol was exchanged without net reduction in the concentration of viral membrane cholesterol. Part of the loss in infectivity following depletion of cholesterol could be restored by reincorporation of cholesterol in the membrane, thus demonstrating that membrane cholesterol partly contributes to the infectivity of vesicular stomatitis virus.

Alteration of the membrane lipid composition and infectivity of vesicular stomatitis virus by growth in a Chinese hamster ovary cell sterol mutant and in lipid-supplemented baby hamster kidney clone 21 cells

The cholesterol and phospholipid composition of the membrane of vesicular stomatitis (VS) virus was altered by growth in a sterol auxotroph Chinese hamster ovary (CHO MI) host cell and by infection of CHO MI and baby hamster kidney (BHK)-21 cells supplemented with fatty acids and dimethylethanolamine. VS virus released from infected CHO MI sterol auxotroph cells grown in delipidated serum had a 50% lower ratio of cholesterol to phospholipid and an 80% drop in infectivity measured by plaque formation on L-929 cells compared with VS virus released from infected CHO MI cells grown in fetal calf serum. When VS virus was harvested from infected BHK-21 cells fed the choline analogue dimethylethanolamine, 29% of the membrane phospholipids were phosphatidyldimethylethanolamine (PDME); 87% of the PDME was located in the external monolayer of the virus membrane as determined by phospholipase C hydrolysis. Exogenous fatty acids added to the medium of cells infected with VS virus comprised up to 30% of the fatty acyl chains of the viral glycerophospholipids. The presence of PDME or unusual fatty acyl chains in the viral membrane had no effect on viral infectivity. These data indicate that the lipid composition of the VS virus membrane is determined primarily by the lipids available in the host cell and that only cholesterol content affects the biological activity of the virus membrane.

Thermotropic behavior of dipalmitoylphosphatidylcholine vesicles reconstituted with the glycoprotein of vesicular stomatitis virus

The vesicular stomatitis virus glycoprotein reconstituted into dipalmitoylphosphatidylcholine (DPPC) vesicles exerts a profound effect upon the DPPC gel to liquid-crystalline phase transition. The glycoprotein was reconstituted into DPPC vesicles by octyl glucoside dialysis. The gel to liquid-crystalline phase transition of these vesicles was monitored by differential scanning calorimetry. Vesicles formed in the absence of glycoprotein (600--2100-A diameter) underwent the phase transition at 41.0 degrees C and had an associated enthalpy change of 8.0 +/- 1.6 kcal/mol. Increasing the mole ratio of glycoprotein to DPPC in the vesicles to 0.15 mol % reduced both the transition temperature and the transition enthalpy change. The enthalpy change as a function of the mole percent glycoprotein could be fit to a straight line by a least-squares procedure. Extrapolation of the results to the glycoprotein concentration where the enthalpy change was zero indicated one glycoprotein molecule bound 270 +/- 150 molecules of DPPC.

Aircraft disinsecting: the effectiveness of Freon-based and water-based phenothrin and permethrin aerosols

In Miami, Florida, USA, passenger compartments of jet aircraft were disinsected at "blocks away". An application of a 20 g/litre Freon-based or water-based permethrin formulation at 35 mg of aerosol per 100 m(3) was 100% effective against caged mosquitos and flies. The flammability hazard of the sprays from water-based hydrocarbon aerosols was evaluated.

Species complexes in the Simuliidae

The recent discovery that Simulium damnosum in Africa is not a single species but a complex of sibling species has important implications for the epidemiology and control of onchocerciasis. This paper sets out the current situation with regard to classification within the S. damnosum complex and the smaller S. neavei group. The nomenclature of the S. damnosum complex and current morphological and enzyme electrophoretic methods of differentiating among sibling species are discussed. Finally, recommendations are made on priorities for future research.

A comparison of Freon- and water-based insecticidal aerosols for aircraft disinsection

In Miami, USA, passenger compartments of wide-bodied jet aircraft were disinsected at "blocks away" or while parked. The application of 2% Freon- and water-based formulations of (+)-phenothrin at about 35 g/100 m(3) was highly effective against mosquitos and flies in all instances. More basic research is needed on water-based aerosols.

Possible Surface Reactions on Mars: Implications for Viking Biology Results

The results of two of the three biology experiments carried out on the Viking Mars landers have been simulated. The mixture of organic compounds labeled with carbon-14 used on Mars released carbon dioxide containing carbon-14 when reacted with a simulated martian surface and atmosphere exposed to ultraviolet light (labeled release experiment). Oxygen was released when metal peroxides or superoxides were treated with water (gas exchange experiment). The simulations suggest that the results of these two Viking experiments can be explained on the basis of reactions of the martian surface and atmosphere.

Antileukemic and other constituents of Tithonia tagitiflora Desf

Phytochemical investigation of Tithonia tagitiflora has led to isolation of six new germacranolides, tagitinins A, B, C, D, E, AND F, beta-sitosterol, and its beta-D-glucoside. Among these, tagitinin F possesses antileukemic activity.

Aircraft disinfection: the physical and insecticidal characteristics of (+)-phenothrin applied by aerosol at "blocks away"

A 2% formulation of (+)-phenothrin dispensed from 340-g or break-off tip aerosol cans was highly effective against mosquitos in aircraft disinsection trials. Two minutes after application at "blocks away", the mass median diameter of the dispersed drops was 5.1-6.2 mum. The concentration of the insecticide in the cabin fell to 10% of the original concentration after 9.2 min. No odour or irritation was caused by the use of this insecticide.