scholarly journals Immune Response to Verotoxin 1 and 2 in Children withEscherichia ColiO157:H7 Hemorrhagic Colitis and Classic Hemolytic Uremic Syndrome

1995 ◽  
Vol 6 (3) ◽  
pp. 136-140 ◽  
Author(s):  
François Proulx ◽  
Jean P Turgeon ◽  
Gilles Delage ◽  
Hermy Lior ◽  
Lucette Lafleur ◽  
...  
Keyword(s):  
Immune Response ◽  
Hemolytic Uremic Syndrome ◽  
Neutralizing Antibody ◽  
Hemorrhagic Colitis ◽  
Serum Samples ◽  
Fourfold Increase ◽  
Antibody Titres ◽  
Uremic Syndrome ◽  
Antibody Levels ◽  
Positive Immune Response

Objectives: To compare neutralizing antibody titres against verotoxin (vt)-1andvt-2between children with uncomplicated hemorrhagic colitis (hc) and those with classic hemolytic uremic syndrome (hus).vtantibody titres were also compared in children withhcwho received trimethoprim-sulfamethoxazole with those who did not.Design: Prospective study.Setting: Tertiary pediatric hospital.Population Studied: Children withhc(n=41) or classichus(n=12).Interventions: Serum antibodies againstvt-1andvt-2were determined by quantitative neutralization.Main Results: Antibodies were detected in 40% (21 of 53) of serum samples forvt-1and in 100% (53 of 53) of samples forvt-2. A positive immune response, defined as a fourfold increase invtantibody titres or as a single titre of 1/64 or greater, was found in 0% (0 of 12) of patients withhuscompared with 7% (three of 41) of those withhcforvt-1(P=0.4); and in 17% (two of 12) of patients withhuscompared with 22% (nine of 41) of those withhcforvt-2(P=0.3). The rate of seroconversion against eithervt-1orvt-2was comparable in treated and untreated patients with uncomplicatedhc.Conclusions: There was no evidence that neutralizing antibody levels againstvt-1orvt-2in classichusor after antibiotic therapy are substantially different from those in patients with uncomplicatedhc.

scholarly journals Infection by verocytotoxin-producing Escherichia coli.

1989 ◽  
Vol 2 (1) ◽  
pp. 15-38 ◽  
Author(s):  
M A Karmali
Keyword(s):  
Escherichia Coli ◽  
Hemolytic Uremic Syndrome ◽  
Mammalian Cells ◽  
Significant Risk ◽  
Public Health Problem ◽  
Hemorrhagic Colitis ◽  
Commercial Development ◽  
High Biological Activity ◽  
Systemic Complications ◽  
Uremic Syndrome

Verocytotoxin (VT)-producing Escherichia coli (VTEC) are a newly recognized group of enteric pathogens which are increasingly being recognized as common causes of diarrhea in some geographic settings. Outbreak studies indicate that most patients with VTEC infection develop mild uncomplicated diarrhea. However, a significant risk of two serious and potentially life-threatening complications, hemorrhagic colitis and the hemolytic uremic syndrome, makes VTEC infection a public health problem of serious concern. The main reservoirs of VTEC appear to be the intestinal tracts of animals, and foods of animal (especially bovine) origin are probably the principal sources for human infection. The term VT refers to a family of subunit exotoxins with high biological activity. Individual VTEC strains elaborate one or both of at least two serologically distinct, bacteriophage-mediated VTs (VT1 and VT2) which are closely related to Shiga toxin and are thus also referred to as Shiga-like toxins. The holotoxins bind to cells, via their B subunits, to a specific receptor which is probably the glycolipid, globotriosyl ceramide (Gb3). Binding is followed by internalization of the A subunit, which, after it is proteolytically nicked and reduced to the A1 fragment, inhibits protein synthesis in mammalian cells by inactivating 60S ribosomal subunits through selective structural modification of 28S ribosomal ribonucleic acid. The mechanism of VTEC diarrhea is still controversial, and the relative roles of locally acting VT and "attaching and effacing adherence" of VTEC to the mucosa have yet to be resolved. There is increasing evidence that hemolytic uremic syndrome and possibly hemorrhagic colitis result from the systemic action of VT on vascular endothelial cells. The role of antitoxic immunity in preventing the systemic complications of VTEC infection is being explored. Antibiotics appear to be contraindicated in the treatment of VTEC infection. The most common VTEC serotype associated with human disease is O157:H7, but over 50 different VT-positive O:H serotypes have now been identified. The best strategies for diagnosing human VTEC infection include testing for the presence of free VT in fecal filtrates and examining fecal cultures for VTEC by means of deoxyribonucleic acid probes that specify genes encoding VT1 and VT2. Both methods are currently confined to specialized laboratories and await commercial development for wider use. In the meantime, most laboratories should continue to screen for the most common human VTEC serotype, O157:H7, using a sorbitol-containing MacConkey medium.

scholarly journals Investigations on the incidence of rinderpest virus infection in game animals of N. Tanganyika and S. Kenya 1960/63

1967 ◽  
Vol 65 (3) ◽  
pp. 343-358 ◽  
Author(s):  
W. Plowright ◽  
B. McCulloch
Keyword(s):  
Clinical Signs ◽  
Neutralizing Antibody ◽  
Low Grade ◽  
Serum Samples ◽  
Before And After ◽  
Antibody Titres ◽  
Low Incidence ◽  
Connochaetes Taurinus ◽  
Low Rate ◽  
Game Animals

The incidence of rinderpest infection in game animals in selected localities of South Kenya and North Tanganyika was studied during the period 1960 to 1963. Serum samples from 590 wildebeest (Connochaetes taurinus), 48 eland (Taurotragus oryx), 65 Thompson's gazelle (Gazella thompsoni) and 39 Grant's gazelle (Gazella granti) were tested for rinderpest neutralizing antibody.Rinderpest infection was shown to have been very frequent in yearling wilde-beest in the Mara area of Kenya in 1959/60, in the Serengeti National Park of Tanganyika in late 1960 and also in the Serengeti, and some adjacent areas, during the latter half of 1961. In the Ngorongoro Crater in 1961 infection was far less widespread, with only 11% of the yearlings acquiring antibody, compared to 67% in the Serengeti. The infections in 1959 and 1960 were clinical epizootics, accompanied by a considerable mortality, whereas no overt disease was reported in the course of 1961. Eland were affected in a similar manner to wildebeest up to 1960 but only a low rate of serological conversion was demonstrated in 1961. Adult Thompson's gazelle showed a low rate (ca. 12%) of infection but no anti-body was detected in Grant's gazelle.Only a small proportion of the wildebeest calves born in early 1962 acquired antibody by mid-1963 and this was due, at least in part, to infection late in 1962; it was not clear, unfortunately, whether the positive animals belonged entirely to resident, as opposed to migratory, groups. No clinical signs or mortality were reported in this year.A low incidence of rinderpest infection in wildebeest was also demonstrated both before and after 1960 in the Kajiado district of Kenya, where disease of game has not been reported in recent years. It is possible that the positive animals, as also the 1962 cases in Tanganyika, acquired the virus from low-grade infections of cattle.The transmission of rinderpest antibody from wildebeest dam to calf, presumably via the colostrum, was demonstrated regularly, except in six calves about 1–2 weeks old. No completely satisfactory explanation was obtained for their failure to acquire passive antibody but it may have been due to abnormal disturbance in the herds, associated with the shooting. The antibody titres in calves were initially higher than those in the serum of their dams but by the end of the 3rd month this position had been reversed. Individual calves became serologically negative from about the 10th week of life and all were devoid of antibody by the 6th to 7th month. The half-life of passively-acquired antibody was 4·4 weeks.

Hemorrhagic colitis caused by Escherichia coli preceding hemolytic-uremic syndrome: radiologic features.

1992 ◽  
Vol 158 (3) ◽  
pp. 551-552 ◽  
Author(s):  
O Tanaka ◽  
K Matsuura ◽  
J Nagai ◽  
S Mitsu ◽  
T Kimura ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hemolytic Uremic Syndrome ◽  
Hemorrhagic Colitis ◽  
Uremic Syndrome ◽  
Radiologic Features

scholarly journals Neutralizing antibody titres to SARS-CoV-2 Omicron variant and wild-type virus in those with past infection or vaccinated or boosted with mRNA BNT162b2 or inactivated CoronaVac vaccines

2022 ◽  
Author(s):  
Malik Peiris ◽  
Samuel Cheng ◽  
Chris Ka Pun Mok ◽  
Yonna Leung ◽  
Susanna Ng ◽  
...  
Keyword(s):  
Protective Immunity ◽  
Neutralization Test ◽  
Neutralizing Antibody ◽  
Wild Type Virus ◽  
Wild Type ◽  
Past Infection ◽  
Post Vaccination ◽  
Antibody Titres ◽  
Duration Of Protection ◽  
Antibody Levels

Abstract Omicron, a novel SARS-CoV-2 variant has emerged and is rapidly becoming the dominant SARS-CoV-2 virus circulating globally. It is important to define reductions in virus neutralizing activity in serum of convalescent or vaccinated individuals to understand potential loss of protection from infection or re-infection. Two doses of BNT162b2 or CoronaVac vaccines provided little 50% plaque reduction neutralization test (PRNT50) antibody immunity against the Omicron variant, even at one-month post vaccination. Booster doses with BNT162b2 in those with two doses of either BNT162b2 or CoronaVac provided acceptable neutralizing immunity against Omicron variant at 1-month post-booster dose. However, three doses of BNT162b2 elicited higher levels of PRNT50 antibody to Omicron variant suggesting longer duration of protection. Convalescent from SARS-CoV-2 infection did not have protective PRNT50 antibody levels to Omicron, but a single dose of BNT162b2 vaccine provided protective immunity. Field vaccine-efficacy studies against Omicron variant against different vaccines are urgently needed.

Neutralizing antibody titers six months after Comirnaty vaccination: kinetics and comparison with SARS-CoV-2 immunoassays

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Andrea Padoan ◽  
Chiara Cosma ◽  
Francesco Bonfante ◽  
Foscarina della Rocca ◽  
Francesco Barbaro ◽  
...  
Keyword(s):  
Vaccine Dose ◽  
Neutralizing Antibody ◽  
University Hospital ◽  
Serum Samples ◽  
Viral Neutralization ◽  
Previous Infection ◽  
Antibody Titers ◽  
Males And Females ◽  
Antibody Levels

Abstract Objectives mRNA vaccines, including Comirnaty (BNT162b2 mRNA, BioNTech-Pfizer), elicit high IgG and neutralizing antibody (NAb) responses after the second dose, but the progressive decrease in serum antibodies against SARS-CoV-2 following vaccination have raised questions concerning long-term immunity, decreased antibody levels being associated with breakthrough infections after vaccination, prompting the consideration of booster doses. Methods A total number of 189 Padua University-Hospital healthcare workers (HCW) who had received a second vaccine dose were asked to collect serum samples for determining Ab at 12 (t12) and 28 (t28) days, and 6 months (t6m) after their first Comirnaty/BNT162b2 inoculation. Ab titers were measured with plaque reduction neutralization test (PRNT), and three chemiluminescent immunoassays, targeting the receptor binding domain (RBD), the trimeric Spike protein (trimeric-S), and surrogate viral neutralization tests (sVNT). Results The median percentages (interquartile range) for decrease in antibodies values 6 months after the first dose were 86.8% (67.1–92.8%) for S-RBD IgG, 82% (58.6–89.3%) for trimeric-S, 70.4% (34.5–86.4%) for VNT-Nab, 75% (50–87.5%) for PRNT50 and 75% (50–93.7%) for PRNT90. At 6 months, neither PRNT titers nor VNT-Nab and S-RBD IgG bAb levels correlated with age (p=0.078) or gender (p=0.938), while they were correlated with previous infection (p<0.001). Conclusions After 6 months, a method-independent reduction of around 90% in anti-SARS-CoV-2 antibodies was detected, while no significant differences were found between values of males and females aged between 24 and 65 years without compromised health status. Further efforts to improve analytical harmonization and standardization are needed.

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