scholarly journals Complement component C3 fixes selectively to the major outer membrane protein (MOMP) of Legionella pneumophila and mediates phagocytosis of liposome-MOMP complexes by human monocytes.

1990 ◽  
Vol 172 (4) ◽  
pp. 1201-1210 ◽  
Author(s):  
C Bellinger-Kawahara ◽  
M A Horwitz
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Legionella Pneumophila ◽  
Alternative Pathway ◽  
Major Outer Membrane Protein ◽  
Complement Component ◽  
Enzyme Linked Immunosorbent Assay ◽  
Human Monocytes ◽  
Complement Component C3

Legionella pneumophila is a facultative intracellular bacterial pathogen that parasitizes human monocytes and alveolar macrophages. Previous studies from this laboratory have shown that monocyte complement receptors CR1 and CR3 and complement component C3 in serum mediate L. pneumophila phagocytosis. In this study, we have explored C3 fixation to L. pneumophila. We developed a whole-cell enzyme-linked immunosorbent assay (ELISA) to measure C3 fixation to the bacterial surface. By this assay, C3 fixes to L. pneumophila that are opsonized in fresh nonimmune serum, and C3 fixation takes place via the alternative pathway of complement activation. Immunoblot analysis of opsonized L. pneumophila indicated that C3 fixes selectively to specific acceptor molecules of L. pneumophila. Consistent with this, when nitrocellulose blots of whole L. pneumophila or bacterial components are incubated in fresh nonimmune serum, C3 fixes exclusively to the major outer membrane protein (MOMP) of L. pneumophila, a porin; C3 does not fix to L. pneumophila LPS on these blots. To further explore the role of MOMP in C3 fixation and phagocytosis, we reconstituted purified MOMP into liposomes. By the ELISA, MOMP-liposomes, but not plain liposomes lacking MOMP, avidly fix C3. Consistent with a dominant role for MOMP in C3 fixation, MOMP-liposomes form a C3 complex of the same apparent molecular weight as whole L. pneumophila in nonimmune serum. Opsonized radioiodinated MOMP-liposomes avidly adhere to monocytes, and adherence is dose dependent upon serum. By electron microscopy, opsonized MOMP-liposomes are efficiently phagocytized by human monocytes, and phagocytosis takes place by a conventional appearing form of phagocytosis. This study demonstrates that C3 fixes selectively to the MOMP of L. pneumophila, and that, in the presence of nonimmune serum, MOMP can mediate phagocytosis of liposomes and, potentially, phagocytosis of intact L. pneumophila by human monocytes.

Enzyme-linked Immunosorbent Assay (ELISA) for Legionella pneumophila Using Outer Membrane Protein

1987 ◽  
Vol 61 (6) ◽  
pp. 652-661
Author(s):  
Takashige MIYAZAKI ◽  
Manabu NAKASHIMA ◽  
Shigeru KONO ◽  
Hironobu KOGA ◽  
Hiroko NAKAZATO ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Immunosorbent Assay ◽  
Outer Membrane Protein ◽  
Legionella Pneumophila ◽  
Enzyme Linked Immunosorbent Assay

scholarly journals Antibody Responses to Recombinant Protein Fragments of the Major Outer Membrane Protein and Polymorphic Outer Membrane Protein POMP90 in Chlamydophila abortus-Infected Pregnant Sheep

2005 ◽  
Vol 12 (6) ◽  
pp. 770-777 ◽  
Author(s):  
Morag Livingstone ◽  
Gary Entrican ◽  
Sean Wattegedera ◽  
David Buxton ◽  
Iain J. McKendrick ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Environmental Contamination ◽  
Major Outer Membrane Protein ◽  
Control Measures ◽  
Enzyme Linked Immunosorbent Assay ◽  
Chlamydophila Abortus ◽  
Pregnant Sheep ◽  
Variable Segment

ABSTRACT Chlamydophila abortus is one of the major causes of infectious abortion in pregnant sheep (enzootic abortion of ewes or EAE) worldwide. Organisms shed in infected placentas and uterine discharges at lambing time are the main sources of environmental contamination, responsible for transmission to susceptible animals and possible human contacts. In the present study, a recently developed test, based on a recombinant fragment of the polymorphic outer membrane protein POMP90 (rOMP90-4 indirect enzyme-linked immunosorbent assay [iELISA]) and one based on the variable segment 2 (VS2) region of the major outer membrane protein (MOMP) (MOMP VS2 iELISA) were compared using sera from C. abortus-infected ewes at different stages throughout pregnancy. The rOMP90 iELISA detected antibody much earlier in pregnancy than the MOMP iELISA, which, like the complement fixation test, detected antibody only at the time of abortion or lambing. No anti-MOMP antibody response could be detected in three of seven experimentally infected ewes. Furthermore, the rOMP90 iELISA detected antibody in an animal that seroconverted during the course of the study, which the MOMP iELISA failed to detect. Overall, the results show that the rOMP90-4 iELISA is considerably more sensitive than the MOMP VS2 iELISA for identifying animals infected with C. abortus. Earlier detection of infection will allow appropriate control measures to be taken to reduce environmental contamination, thus limiting the spread of infection, financial losses, and the possible risks of zoonotic transmission to humans.

scholarly journals Major Outer Membrane Protein from Legionella pneumophila Inhibits Phagocytosis but Enhances Chemotaxis of RAW 264.7 Macrophages by Regulating the FOXO1/Coronin-1 Axis

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zehui Yang ◽  
Yingying Chen ◽  
Qiang Zhang ◽  
Xiaodong Chen ◽  
Ze Deng
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Legionella Pneumophila ◽  
Major Outer Membrane Protein ◽  
Raw 264.7 ◽  
Dependent Manner ◽  
Raw 264.7 Macrophages ◽  
Expression Levels ◽  
Raw 264.7 Macrophage

Legionella pneumophila is an intracellular pathogen that can cause Legionnaire’s disease by invading alveolar epithelial cells and macrophages. The major outer membrane protein (MOMP) plays an important role in the interaction between bacteria and host cells. However, the role of MOMP in the process of L. pneumophila invasion of macrophages and its working mechanism remain unknown. We aimed to explore the effects of MOMP on phagocytosis and chemotaxis of RAW 264.7 macrophages. The chemotactic activity, toxicity, and phagocytosis of RAW 264.7 cocultured with different concentrations of MOMP were determined by Transwell, CCK-8, and neutral red uptake assays, respectively. Target genes were detected by double-luciferase and pull down assays. qRT-PCR and Western blot were performed to analyze the expression of several important proteins involved in the immune response pathway, including coronin-1, interleukins (IL-10), forkhead transcription factor 1 (FOXO1), nucleotide-binding oligomerization domain protein (NOD) 1, NOD2, and receptor-interacting protein (RIP) 2. After coculturing with MOMP, cytological observation indicated a decrease of phagocytosis and a marked increase of chemotaxis in RAW 264.7 macrophages. The phagocytosis degree of RAW 264.7 macrophage varied with the concentration gradient of MOMP in a time-dependent manner. MOMP could increase the expression levels of MCP-1, IL-10, NOD2, and RIP2 and decrease the expression levels of FOXO1 and coronin-1 in cell culture supernatants. In addition, we found that FOXO1 could promote its transcription by binding to the promoter of coronin-1. The results of the present study suggested that MOMP could inhibit phagocytosis and facilitate chemotaxis of RAW 264.7 macrophage, which might be associated with the FOXO1/coronin-1 axis.

scholarly journals Recombinant PorA, the Major Outer Membrane Protein of Campylobacter jejuni, Provides Heterologous Protection in an Adult Mouse Intestinal Colonization Model

2010 ◽  
Vol 17 (11) ◽  
pp. 1666-1671 ◽  
Author(s):  
Anjum Islam ◽  
Raj Raghupathy ◽  
M. John Albert
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Campylobacter Jejuni ◽  
Outer Membrane Protein ◽  
Lavage Fluid ◽  
Major Outer Membrane Protein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Food Borne ◽  
Colonization Model ◽  
O 19

ABSTRACT Immunity against Campylobacter jejuni, a major food-borne pathogen causing diarrhea, is largely serotype specific. The major outer membrane protein (MOMP) of C. jejuni, PorA, is a common antigen with the potential to provide broad protection. Adult BALB/c mice were orally immunized with a recombinant glutathione S-transferase (GST) fused to PorA prepared from Campylobacter jejuni C31 (O:6,7) (GST-PorA) combined with a modified heat-labile enterotoxin of Escherichia coli as an adjuvant and later orally challenged with C31 strain or three heterologous strains: 48 (O:19), 75 (O:3), and 111 (O:1,44). Protection from colonization with the challenge organism was studied by fecal screening daily for 9 days. Serum and intestinal lavage fluid antibodies against the vaccine and Sarkosyl-purified MOMP from C31 were measured by using an enzyme-linked immunosorbent assay. The vaccine produced robust antibody responses against both antigens in serum and secretion. Since strain C31 was a poor colonizer, homologous protection could not be studied. The protective efficacies of heterologous strains were 43% (for strain 48, P < 0.001), 29% (for strain 75, P < 0.005), and 42% (for strain 111, P < 0.001) for the 9-day period compared to control mice given phosphate-buffered saline. Thus, PorA provided appreciable protection against colonization with heterologous serotypes.

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