Cutting edge: preferentially the R-stereoisomer of the mycoplasmal lipopeptide macrophage-activating lipopeptide-2 activates immune cells through a toll-like receptor 2- and MyD88-dependent signaling pathway

Mycoplasmas and their membranes are potent activators of macrophages, the active principle being lipoproteins and lipopeptides. Two stereoisomers of the mycoplasmal lipopeptide macrophage-activating lipopeptide-2 (MALP-2) differing in the configuration of the lipid moiety were synthesized and compared in their macrophage-activating potential, the R-MALP being >100 times more active than the S-MALP in stimulating the release of cytokines, chemokines, and NO. To assess the role of the Toll-like receptor (TLR) family in mycoplasmal lipopeptide signaling, the MALP-2-mediated responses were analyzed using macrophages from wild-type, TLR2-, TLR4-, and MyD88-deficient mice. TLR2- and MyD88-deficient cells showed severely impaired cytokine productions in response to R- and S-MALP. The MALP-induced activation of intracellular signaling molecules was fully dependent on both TLR2 and MyD88. There was a strong preference for the R-MALP in the recognition by its functional receptor, TLR2.

Induction of cytokines and chemokines in human monocytes by Mycoplasma fermentans-derived lipoprotein MALP-2

Bacterial infections are characterized by strong inflammatory reactions. The responsible mediators are often bacterially derived cell wall molecules, such as lipopolysaccharide or lipoteichoic acids, which typically stimulate monocytes and macrophages to release a wide variety of inflammatory cytokines and chemokines. Mycoplasmas, which lack a cell wall, may also stimulate monocytes very efficiently. This study was performed to identify mycoplasma-induced mediators. We investigated the induction of cytokines and chemokines in human monocytes exposed to the Mycoplasma fermentans-derived membrane component MALP-2 (macrophage-activating lipopeptide 2) by dose response and kinetic analysis. We found a rapid and strong MALP-2-inducible chemokine and cytokine gene expression which was followed by the release of chemokines and cytokines with peak levels after 12 to 20 h. MALP-2 induced the neutrophil-attracting CXC chemokines interleukin-8 (IL-8) and GRO-alpha as well as the mononuclear leukocyte-attracting CC chemokines MCP-1, MIP-1alpha, and MIP-1beta. Production of the proinflammatory cytokines tumor necrosis factor alpha and IL-6 started at the same time as chemokine release but required 10- to 100-fold-higher MALP-2 doses. The data show that the mycoplasma-derived lipopeptide MALP-2 represents a potent inducer of chemokines and cytokines which may, by the attraction and activation of neutrophils and mononuclear leukocytes, significantly contribute to the inflammatory response during mycoplasma infection.

CD4+ tumor-infiltrating lymphocytes in cervical cancer recognize HLA-DR-restricted peptides provided by human papillomavirus-E7

Human papillomavirus (HPV)-encoded proteins may provide targets for CD8+ or CD4+ T lymphocytes infiltrating into cervical cancer. We established an MHC class II-restricted CD4+ T cell line from a patient with cervical cancer that recognizes autologous (HPV35+, HPV59+) cervical cancer cells and the HLA-DR4-matched cervical cancer cell line Me180 (HPV68+) as determined by TNF-alpha secretion. Expression of different HPV-E7 genes in autologous B cells revealed that this T cell line defines a DR4-presented T cell epitope that is shared among the E7 genes of HPV59 and HPV68. MHC class II-presented peptides may be implemented to augment T cell responses directed against autologous tumor cells, particularly if cancer cells lack MHC class I expression, which is a frequent event in the evolution of cervical cancer.

A single amino acid substitution in SecY stabilizes the interaction with SecA

The SecYEG complex constitutes a protein conducting channel across the bacterial cytoplasmic membrane. It binds the peripheral ATPase SecA to form the translocase. When isoleucine 278 in transmembrane segment 7 of the SecY subunit was replaced by a unique cysteine, SecYEG supported an increased preprotein translocation and SecA translocation ATPase activity, and allowed translocation of a preprotein with a defective signal sequence. SecY(I278C)EG binds SecA with a higher affinity than normal SecYEG, in particular in the presence of ATP. The increased translocation activity of SecY(I278C)EG was confirmed in a purified system consisting of SecYEG proteoliposomes, while immunoprecipitation in detergent solution reveal that translocase-preprotein complexes are more stable with SecY(I278C) than with normal SecY. These data imply an important role for SecY transmembrane segment 7 in SecA binding. As improved SecA binding to SecY was also observed with the prlA4 suppressor mutation, it may be a general mechanism underlying signal sequence suppression.

Cysteine-directed cross-linking demonstrates that helix 3 of SecE is close to helix 2 of SecY and helix 3 of a neighboring SecE

Preprotein translocation in Escherichia coli is mediated by translocase, a multimeric membrane protein complex with SecA as the peripheral ATPase and SecYEG as the translocation pore. Unique cysteines were introduced into transmembrane segment (TMS) 2 of SecY and TMS 3 of SecE to probe possible sites of interaction between the integral membrane subunits. The SecY and SecE single-Cys mutants were cloned individually and in pairs into a secYEG expression vector and functionally overexpressed. Oxidation of the single-Cys pairs revealed periodic contacts between SecY and SecE that are confined to a specific alpha-helical face of TMS 2 and 3, respectively. A Cys at the opposite alpha-helical face of TMS 3 of SecE was found to interact with a neighboring SecE molecule. Formation of this SecE dimer did not affect the high-affinity binding of SecA to SecYEG and ATP hydrolysis, but blocked preprotein translocation and thus uncouples the SecA ATPase activity from translocation. Conditions that prevent membrane deinsertion of SecA markedly stimulated the interhelical contact between the SecE molecules. The latter demonstrates a SecA-mediated modulation of the protein translocation channel that is sensed by SecE.

Effective chemokines and cytokines in the rejection of human retinal pigment epithelium (RPE) cell grafts

OBJECTIVE

In the rejection of transplanted retinal pigment epithelium (RPE) cells, an activation of allografts is probably the pivotal point for long-term success. The detailed immunological interactions involved in the rejection after RPE transplantation are still unknown. The aim of this study is to evaluate the interactions of pro-inflammatory cytokines and chemokines in this activation process in vitro.

METHODS

Human RPE cells (2 x 10(5)/ml) were therefore activated through a pre-treatment with different concentrations of interferon (IFN)-gamma (100 or 1000 U/ml), tumour necrosis factor (TNF)-alpha (1 or 10 ng/ml) or combinations of both, or employed in a nonactivated form. Afterwards, the RPE cells were tested by enzyme-linked immunosorbant assay (ELISA) and ribonuclease protection assays (RPA) for the secretion and mRNA content of the different chemokines (RANTES, MCP-1 and IL-8) and cytokines (IL-6) at various time points up to 48 h.

MAIN FINDINGS

HRPE cells secrete the investigated cytokines in response to pro-inflammatory activation. This could be demonstrated at both the mRNA (RPA) and the protein levels (ELISA). The secretion was time and dose dependent, and significantly upregulated in comparison to that observed with nonactivated cells.

CONCLUSIONS

This study demonstrates that RPE cells efficiently secrete such cytokines as RANTES, MCP-1, IL-6, and IL-8, and have an accountable neutrophil and monocyte chemotactic activity. Thus, it could be indicated that the investigated cytokines play a central role in the activation cascade of RPE and in RPE rejection as well.

Differential expression of monocyte chemotactic protein-1 (MCP-1) in transforming rat hepatic stellate cells

BACKGROUNDS/AIMS

Hepatic stellate cells and infiltrating leukocytes play a key role in the pathogenesis of liver fibrosis. The chronic phase of liver inflammation is characterized by immigrating mononuclear cells. To understand the underlying mechanisms responsible for the attraction of mononuclear cells in the pathogenesis of liver fibrosis, we investigated the inducible production of chemotactic activities in hepatic stellate cells.

METHODS

Cultured hepatic stellate cells of different transformation grades and after in vitro transformation to myofibroblast-like cells were stimulated with tumor necrosis factor-a or bacterial lipopolysaccharide. Mononuclear cell attracting chemotactic activities were evaluated by chemotaxis assays, ELISA, and Northern blot analysis.

RESULTS

We observed a transformation grade-dependent differential responsiveness of hepatic stellate cells and myofibroblast-like cells. Monocyte chemotactic protein-1 was inducible by tumor necrosis factor-alpha in non-transformed hepatic stellate cells. In contrast, monocyte chemotactic protein-1 was not inducible by bacterial lipopolysaccharide until the cells were fully transformed into myofibroblast-like cells. Despite a delayed onset, the bacterial lipopolysaccharide-inducible monocyte chemotactic protein-1 expression did not depend on an endogenous production of tumor necrosis factor-alpha.

CONCLUSIONS

Our results indicate that the tumor necrosis factor-alpha and bacterial lipopolysaccharide-inducible production of chemokines plays a central role in the pathogenesis of liver fibrosis. These data suggest that when hepatic stellate cells have been transformed to a myofibroblast-like cells phenotype, e.g. by chronic injury, the cells become more sensitive to bacterial lipopolysaccharide, which may potentiate the production of chemotactic and fibrogenic mediators. A strong secretion of monocyte chemotactic protein-1 may contribute to the maintenance of an inflammatory infiltrate dominated by mononuclear cells.

Differential mononuclear leukocyte attracting chemokine production after stimulation with active and inactivated influenza A virus

After influenza A virus infection of human monocytes, we found a rapid and marked release of the mononuclear cell attracting chemokines MCP-1, MIP-1 alpha, and IP-10, with corresponding gene expression patterns as determined by Northern blot analysis. In striking contrast, the expression and release of the neutrophil chemoattractant IL-8 was not inducible. To determine the underlying mechanisms responsible for the induction of this differential chemokine pattern, we stimulated monocytes with UV- and heat-inactivated (56 degrees C and 100 degrees C) influenza A virus. In comparison with fully infectious influenza A, 56 degrees C-inactivated virus induced a strong production of MCP-1, MIP-1 alpha, and IP-10, while the release of MIP-1 alpha and IP-10 was substantially lower after exposure to UV-inactivated virus. No chemokine expression was found after stimulation with 100 degrees C-inactivated influenza A virus. Our data indicate that, contingent upon the chemokine examined, the maximal induction depends on the unrestricted infectivity of the virus, the unaltered hemagglutinin molecule, or the intact viral RNA. This diversified chemokine production may enable the infected host to mount an efficient antiviral response against infective and noninfective virus particles.

Lead in wine

Elevated levels of lead in wine have been explained by several possible contamination sources: leaded gasoline, tin-lead capsules (used to cover the bottle neck), and brass alloys. Lead measurements from 7000 wines were used to identify possible sources and these showed that atmospheric pollution-related contamination (leaded gasoline) was not responsible for elevated lead concentrations in wine. It also was shown that the presence or absence of tin-lead capsules as well as the state of tin-lead capsule corrosion had only a very minor influence on the lead concentration in wine. The reported positive correlation between wine age and lead concentration was confirmed by our data. However, further statistical analysis revealed that not the age of wine but the vintage and the wine colour were the most significant contributing factors. The wine age itself was no longer correlated with the lead concentration after controlling for the significant variables mentioned. The conclusions drawn agree well with the explanation that brass is the main contamination source. Inspections of wineries known for elevated lead levels always revealed the presence of brass tubes and faucets. There has been a continuing and significant reduction of lead levels in wine during the recent 7 years where measurements were made.

[Status febrilis and jaundice]

A 49 year old patient was admitted with fever and jaundice. Laboratory evaluation showed leukocytosis, elevated values for C-reactive protein, transaminases, bilirubin and alkaline phosphatase. Ultrasound and subsequent CT-scan revealed multiple liver lesions and a liquid mass in the bursa omentalis. A CT-guided catheter-drainage was performed and streptococcus milleri isolated from the abscess and one blood culture. After empiric broad spectrum treatment with Piperacillin/Tazobactam (Tazobac) and Netilmicin (Netromycin), Ceftriaxon (Rocephin) was given for a total treatment time of 10 days. Further evaluation revealed a perforated peptic ulcer as possible etiology for the described localized infectious complication.

Interaction between SecA and SecYEG in micellar solution and formation of the membrane-inserted state

Preprotein translocation in Escherichia coli is mediated by the translocase with SecA as peripheral ATPase and SecY, SecE, and SecG as membrane domain. To facilitate large-scale purification of the SecYEG heterotrimer, SecY was fused at its amino terminus with a hexahistidine tag and co-overexpressed with SecE and SecG. The presence of the His tag allowed purification of homogeneously pure SecYEG complex by a single anion-exchange chromatographic step starting from octyl glucoside-solubilized inner membranes. Endogenous levels of SecD and SecF copurified with the SecYEG protein. Purified SecYEG complex retained a nativelike, alpha-helical conformation in octyl glucoside and in micellar solution binds SecA with high affinity. In the presence of the nonhydrolyzable nucleotide analogue adenosine 5'-(beta, gamma-imidotriphosphate), octyl glucoside-solubilized SecYEG is nearly as effective as the reconstituted enzyme in inducing the formation of a proteinase K-protected 30 kDa fragment of 125I-labeled SecA, while SecYEG is proteolyzed to fragments smaller than 6 kDa. These data demonstrate that the 30-kDa SecA fragment is not protected by the lipid phase nor by SecYEG but rather indicate that it represents a SecYEG- and nucleotide-induced stable conformational state of a SecA domain.

Hypochlorite-modified LDL: chemotactic potential and chemokine induction in human monocytes

Within blood vessels the accumulation of monocytes/macrophages at sites of modified lipoproteins is an important feature in atherosclerosis. Recently the presence of LDL and other proteins modified by hypochlorous acid (HOCl-LDL) was demonstrated in human atherosclerotic vessels and human inflammatory kidney disease by immunohistology and protein chemistry. Chemokines contribute to a specific and directed migration of inflammatory cells. IL-8 (alpha-chemokine) attracts mainly neutrophils and distinct T-cell subsets while MCP-1 (beta-chemokine) preferentially acts on monocytes/macrophages. In the present study it was postulated that HOCl-LDL may induce and amplify inflammatory reactions by the induction of chemokine synthesis in local monocytes. After exposure of human monocytes to HOCl-LDL, it was found that mRNA and protein of the chemokine IL-8 was strongly induced, while the chemokine MCP-1 was not. HOCl-LDL itself led to a chemotactic migration of neutrophils. A chemotactic response of human monocytes toward HOCl-LDL was not detectable. We propose that HOCl-LDL may represent a form of LDL modification in the atherosclerotic process which initiates leukocyte infiltration; these mononuclear cells have been observed in the early stages of atherosclerosis.

Borrelia burgdorferi induces chemokines in human monocytes

Lyme disease is clinically and histologically characterized by strong inflammatory reactions that contrast the paucity of spirochetes at lesional sites, indicating that borreliae induce mechanisms that amplify the inflammatory response. To reveal the underlying mechanisms of chemoattraction and activation of responding leukocytes, we investigated the induction of chemokines in human monocytes exposed to Borrelia burgdorferi by a dose-response and kinetic analysis. Lipopolysaccharide (LPS) derived from Escherichia coli was used as a positive control stimulus. The release of the CXC chemokines interleukin-8 (IL-8) and GRO-alpha and the CC chemokines MIP-1alpha, MCP-1, and RANTES was determined by specific enzyme-linked immunosorbent assays, and the corresponding gene expression patterns were determined by Northern blot analysis. The results showed a rapid and strong borrelia-inducible gene expression which was followed by the release of chemokines with peak levels after 12 to 16 h. Spirochetes and LPS were comparably effective in stimulating IL-8, GRO-alpha, MCP-1, and RANTES expression, whereas MIP-1alpha production preceded and exceeded chemokine levels induced by LPS. Unlike other bacteria, the spirochetes themselves did not bear or release factors with intrinsic chemotactic activity for monocytes or neutrophils. Thus, B. burgdorferi appears to be a strong inducer of chemokines which may, by the attraction and activation of phagocytic leukocytes, significantly contribute to inflammation and tissue damage observed in Lyme disease.

Fully automated determination of pesticides in wine

A fully automated solid-phase extraction gas chromatographic/mass spectrometric (SPE/GC/MS) method was developed for determination of pesticides in wine. All steps from aspiration of infiltrated wine to printout of the integrated chromatogram were performed without human interaction. A dedicated robot performed addition of internal standard, application of wine onto the SPE cartridge, elution of analytes, drying and concentrating of eluate, and passing of concentrate to the GC sampler. All steps were performed in standard liquid chromatography/GC vials, using a minimum of organic solvent. The method permits determination of 21 different pesticides. Individual detection limits were 0.005-0.01 mg/L. The regression coefficients relating to linearity were > 0.99; only 4,4-dichloro-benzphenone and dicofol showed lower coefficients. The recoveries for 17 pesticides ranged from 80 to 115%.

[The Holt-Oram syndrome. Review of the literature and current orthopedic treatment concepts]

PROBLEM

The clinical manifestation of the Holt-Oram-syndrome (HOS) shows congenital heart-disease and anomalies of the upper limb. The inheritance of this syndrome is autosomal dominant. The question arise, as to whether a contemporary orthopedic concept of treatment could developed based on own experiences and data from the literature.

METHODS

We revised data from five patients with HOS treated at the Clinic for Orthopaedics of the University of Heidelberg. The review of the literature revealed a comprehensive and detailed picture of the clinical syndrome and, furthermore, information in respect to a comparative analysis of methods of treatments.

RESULTS

Our patients showed characteristic cardiac anomalies, i.e. atrio and ventricular septal defects, and persisting Botall's duct (three cases). The types of malformation of the upper limb corresponded with those found in the literature. Furthermore the indication for amputation of rudimentary or hypoplastic fingers in the Heidelberg clinic was in accordance with the clinical treatments described worldwide.

CONCLUSION

The type of treatment of the clubhand in cases with HOS depends on (1) the age and (2) the pattern and degree of accompanying malformations of the upper limb. For patients with aplasia of the thumb or amputation of a rudimental one we recommend pollicisation of the index finger to improve its function.

Induction of neutrophil-attracting chemokines in transforming rat hepatic stellate cells

BACKGROUND & AIMS

Hepatic stellate cells (HSCs) play a key role in the pathogenesis of liver fibrosis. Immigrating leukocytes can potentiate the progression of liver fibrosis by release of fibrogenic mediators and cytotoxic actions. The inducible production of neutrophil chemotactic activities in HSCs was investigated to understand the underlying mechanisms responsible for the attraction of leukocytes in the pathogenesis of liver fibrosis.

METHODS

Cultured HSCs of different transformation grades and after transformation to myofibroblasts (MFBs) were stimulated with tumor necrosis factor (TNF)-alpha and lipopolysaccharide (LPS), respectively. Induced leukocyte chemotactic activities were evaluated by chemotaxis assays, enzyme-linked immunosorbent assay, and Northern blot analysis.

RESULTS

A transformation grade-dependent differential responsiveness of HSCs and MFBs was observed. TNF-alpha-inducible production of chemotactic mediators increased substantially with advancing transformation. Only transformed MFBs were LPS responsive. Macrophage inflammatory protein 2 was identified as one of the inducible chemokines.

CONCLUSIONS

The results suggest that chemokines play an important role in the pathogenesis of liver fibrosis. Proinflammatory cytokines can initiate the production of chemotactic activities. The more HSCs are transformed to MFBs, e.g., by chronic injury, the more sensitive the cells become to LPS, which may lead to a vicious circle of enhanced fibrogenic and chemotactic mediator production.

Single-chain Fv fusion proteins suitable as coating and detecting reagents in a double antibody sandwich enzyme-linked immunosorbent assay

A recombinant enzyme-linked immunosorbent assay (ELISA) system, entirely based on antibody fragments, is described here as an attractive alternative to assays using polyclonal antisera or monoclonal antibodies. Two expression vectors have been developed for cloning and production of single-chain Fv (scFv) fusion proteins suitable as coating and detecting reagents, respectively, in a highly sensitive double antibody sandwich ELISA. The coating reagent is produced from the vector pZIP1, as a bivalent miniantibody with a leucine zipper for dimerization. The detection reagent is a fusion protein, in which a modified Escherichia coli alkaline phosphatase with increased specific activity is attached to the carboxy-terminus of the scFv. This conjugate is produced using pDAP2/S as cloning and expression vector. Optimized bacteria expression and simple one-step purification by hexahistidine tag-mediated metal chelate affinity chromatography yielded milligrams of ELISA reagent per liter of bacterial culture in both cases. A double antibody sandwich ELISA for the detection of beet necrotic yellow vein virus, the causal agent of sugarbeet rhizomania, was developed using fusion proteins obtained by means of pZIP1 and pDAP2/S. The plant pathogen was detected with a sensitivity higher than that reached in a conventional ELISA employing polyclonal antisera. Both plasmid vectors are compatible to phage display vectors such as pHEN1, pCOCK, and the pCANTAB series, allowing simple subcloning after isolation of scFv from phage display libraries. It is therefore easy to develop and produce an ELISA entirely by using bacterial recombination and expression techniques.

Susceptibility of mononuclear phagocytes to influenza A virus infection and possible role in the antiviral response

Among leukocytes, only monocytes and macrophages were found to be highly susceptible to an infection by influenza A virus. After infection, de novo viral protein synthesis was initiated but then interrupted after 4-6 h. Most macrophages died by apoptosis within 25-30 h. Before cell death, however, macrophages responded to influenza A virus with a high cytokine gene transcription and subsequent release of tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1), IL-6, interferon (IFN)-alpha/beta, and CC-chemokines. The basic mechanisms of virus-induced cytokine expression are still unknown and appear to involve transcription factors such as nuclear factor-kappaB and AP-1 which, however, were only activated for 2 h and declined below control values thereafter. After influenza A virus infection, only the mononuclear cell attracting CC-chemokines macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, and RANTES were produced while the prototype neutrophil CXC-chemoattractants IL-8 and GRO-alpha were entirely suppressed. This selective induction of CC-chemokines may explain the preferential influx of mononuclear leukocytes into virus-infected tissue. Our data show that monocytes and macrophages represent a primary target for an influenza A virus infection. Thus, the mononuclear phagocyte response leads to a rapid proinflammatory reaction and an enhanced immigration of mononuclear leukocytes, which may condition the infected host for the subsequent virus antigen-specific defense.

[Investigations on the endoparasitic fauna of domestic cats in eastern Brandenburg]

The internal organs of 155 cats originating from 3 different territories in the eastern part of Brandenburg state were examined for parasites between 1993 and 1995. Parasites were found in 85% of cats. Parasites with the highest prevalence were Toxocara mystax (45%), Hydatigera taeniaeformis (22%), Ancylostoma tubaeforme (17%) and Opisthorchis felineus (16%). Metorchis bilis, Mesocestoides spp., Taenia pisiformis, Capillaria plica, Capillaria sp., Ollulanus tricuspis, Aelurostrongylus abstrusus, Cystoisospora spp. and Sarcocystis spp. were diagnosed with a lower frequency. The occurrence of H. taeniaeforme, A. tubaeformis und O. felineus was depending on the origin of the cats.

Beet soil-borne virus RNA 2: similarities and dissimilarities to the coat protein gene-carrying RNAs of other furoviruses

The complete sequence of the 3454 nt of RNA 2 of the Ahlum isolate of beet soil-borne furovirus (BSBV) has been determined starting with two short stretches of cloned cDNA. Unknown parts of the sequence were amplified by means of RT-PCR techniques using combinations of specific and random primers. BSBV RNA 2 is more similar in its genetic organization to potato mop top virus (PMTV) RNA 3 than to any other furoviral RNA, although it is more than 1100 nt longer. Its 3'-end, unlike that of PMTV RNA 3, has the potential to fold into a tRNA-like structure. It contains one large open reading frame for a readthrough protein with a molecular mass of 104 kDa (104K protein) which is interrupted internally by an amber stop codon terminating the coding region for a protein of 19 kDa (19K), most likely the viral coat protein (CP). The readthrough domain of the 104K protein is much larger than that of PMTV, but the N- and C-proximal portions of these domains are similar for the two viruses. No serological relationships were found between the particles of the two viruses, although more than 50% of the amino acid sequences of the putative CPs are identical.

Effect of water deprivation on eating patterns of lactating cows fed grass and corn pellets ad lib

The present study investigated the effect of 48 h of water deprivation on eating behavior of 12 lactating cows fed grass and corn pellets ad lib. Water deprivation reduced grass and corn pellet intake significantly, with corn pellet intake decreasing earlier than grass intake. The reduction of feed intake was entirely due to a reduction of meal size for both grass and corn-pellet meals. The size of the first meal of the water deprivation period was already reduced by about 30%. Grass-meal frequency increased, whereas corn-pellet meal frequency decreased during water deprivation. Water deprivation also decreased live weight and milk yield by about 12 and 30%, respectively. All parameters returned to baseline values with rehydration. With ad lib access to feed and water, 77% of drafts occurred in relation to meals, but the number of meals clearly exceeded the number of drafts. The results demonstrate that water deprivation rapidly leads to premature meal termination. This is in line with the assumption that an enhanced prandial increase in ruminal fluid osmotality contributes to dehydration-induced hypophagia. Yet, further studies are necessary to prove this assumption and to better understand the complex relationships between eating and drinking in ruminants.

Expression of single-chain antibody fragments (scFv) specific for beet necrotic yellow vein virus coat protein or 25 kDa protein in Escherichia coli and Nicotiana benthamiana

The coding sequences for the variable regions of heavy and light chains of monoclonal antibodies (mAbs) to beet necrotic yellow vein virus (BNYVV) coat protein (cp) or the 25 kDa nonstructural protein (P25) were cloned into the pCOCK vector and expressed as single-chain antibody fragments (scFv) in Escherichia coli. For expression in higher plants the scFv were targeted either to the secretory pathway by including the sequences encoding the pectate lyase B (PelB) or the phytohemagglutinin (PHA) signal peptides in the vector constructs or they were targeted to the cytoplasm by omitting a signal peptide-encoding sequence from the constructs. The scFv were detected mainly in plants in which the PHA signal peptide had been used for targeting demonstrating for the first time the usefulness of this peptide for enabling scFv expression in plants. The scFv were not secreted into the culture fluids of suspension cultures, but were retained in the cells. The amount of expression of scFv in the best expressing plants was at least as high as in bacterial culture supernatants. In a dot blot immunoassay, 0.4 ng BNYVV cp or 0.8 ng P25 were detected by the respective scFv either from E. coli or from plants. The majority of the 21 plants expressing cp-specific scFv had near-normal growth whereas the three plants expressing P25-specific scFv grew poorly and did not form roots.

Selective induction of monocyte and not neutrophil-attracting chemokines after influenza A virus infection

It is characteristic for virus infections that monocytes/macrophages and lymphocytes infiltrate infected tissue while neutrophils are absent. To understand the mechanisms selectively attracting mononuclear cells in viral diseases, we examined in an influenza A virus model the expression and regulation of chemokines as candidate molecules responsible for the immigration of leukocytes into inflamed tissue. After influenza A virus infection of human monocytes, a rapid expression of the mononuclear cell attracting CC-chemokine genes MIP-1, MCP-1, and RANTES occurred which was followed by the release of chemokine proteins. In striking contrast to CC-chemokines, the expression of the prototype neutrophil CXC-chemoattractants IL-8 and GRO-alpha was completely suppressed after influenza A infection. The release of other neutrophil chemotactic factors was excluded by microchemotaxis assays. These results suggest that the virus-specific induction of mononuclear cell-attracting chemokines accounts for the preferential influx of mononuclear leukocytes into virus-infected tissue.