Bactericidal antibody response to Neisseria meningitidis serogroup B in patients with bacterial meningitis: effect of immunization with an outer membrane protein vaccine

We evaluated the bactericidal antibody response to Neisseria meningitidis serogroup B in convalescent patients (n=65) from bacterial meningitis. Patients infected with B meningococci were stratified according to their vaccination status (Cuban BC vaccine) into group 1 (immunized) (n=12) and group 2 (non-immunized) (n=15). The results suggested that antibody titers > or =2 (log(2)) indicate a specific immune response to N. meningitidis. In group 1, 64% of patients had a significant antibody titer (> or =2) in their acute sera against a B:4:P1.15 strain, compared to only 21% of group 2 patients. All patients from group 1 without bactericidal antibodies in their acute sera had a significant increase (at least 2-fold increase in log(2) titers) in antibody titers in their convalescent sera, in contrast, to only 27% of patients from group 2 (P=0.06). Using mutant strains lacking OMP1 or OMP5, it was shown that OMP1 was an important antigen recognized by immunized patients but not by non-immunized patients.     

Evaluation of the level of antibodies to purified meningococcal antigens

Group B meningococcal antigens, such as polysaccharide, lipopolysaccharide, protein preparation, as well as sonicates obtained from meningococcal cells, groups A, B and C, have been isolated. On the basis of these preparations the parameters of an enzyme immunoassay system for the detection of antibodies to individual meningococcal antigens have been established, and the specificity of the system and the possibility of using it for the evaluation of the level of antibodies to meningococci in human sera have been studied.     

Serological diagnosis of brucellosis caused by Brucella canis

Blood serum samples from 2,328 dogs were tested to detect antibodies against Brucella canis with the agar gel immunodiffusion (AGID) and 2-mercaptoethanol slide agglutination test (ME-SAT) using Brucella ovis as the antigen. All blood serum samples were also evaluated for antibodies against Brucella abortus and Brucella melitensis using the Rose Bengal test. Twentyfive (1.07%) of the sera evaluated were considered positive with AGID test. Only 4 (16%) of these blood serum samples were positive when evaluated with ME-SAT. The 25 AGID positive samples and 25 AGID negative serum samples were also examined by: the complement fixation test (CFT) using B. ovis hot saline extract (HSE) as the antigen, indirect enzyme linked immunosorbent assay (ELISA) and immunoblotting (IB) using B. canis and B. ovis HSE antigens. Two positive canine sera from culture positive dogs and the serum of an experimentally RM6/66 B. canis-infected rabbit were employed as positive controls and one serum from a known uninfected dog as a negative control. ELISA with B. canis antigen gave 9 (18%) positive results (6 AGID-positive and 3 AGID-negative sera). ELISA performed with B. ovis antigen detected 15 (30%) positive samples (10 AGID-positive, 5 AGID-negative and 8 B. canis ELISA positive sera). IB analysis of known positive controls sera employing B. canis antigen detected bands with molecular weights of 94-80, 64-50, 35, 32-30, 28, 23, 20-18, 15-12 kDa. The same sera tested with B. ovis antigen revealed bands of 35, 32-30, 25, 23, 20-18, 15-12 kDa. No bands were observed with the negative control serum and the 50 canine tested sera.     

The diagnostic value of a meningococcal-B erythrocyte diagnostic agent based on the group-specific polysaccharide

In this work the diagnostic value of group B meningococcal erythrocyte diagnosticum was determined. 585 blood serum samples taken from adult donors were studied: 220 samples from practically healthy persons and 365 samples from 144 patients with meningococcal infection and purulent bacterial meningitis of nonmeningococcal etiology. Group B meningococcal erythrocyte diagnosticum was found to possess serological activity and to reveal the growth of specific antibodies in the sera of patients with meningococcal infection, serologically confirmed by the isolation of group B meningococcal culture, in 100% of cases on weeks 2-3 of the disease. Diagnostic characteristics--specificity and sensitivity--for group B erythrocyte diagnosticum were, respectively, 90.2% and 63.5%. The study revealed that antibodies to several group-specific meningococcal polysaccharides in blood sera can be simultaneously determined in the passive hemagglutination test with a set of erythrocyte diagnostica, which should be taken into consideration in the clinical interpretation of serological results.     

Serum bactericidal activity in a secondary school population following an outbreak of meningococcal disease: effects of carriage and secretor status

Abstract Sera obtained from 106 children following an outbreak of Neisseria meningitidis (B:4:P1.15) were screened for bactericidal antibodies against isolates of meningococci and Neisseria lactamica . Most had high titres of antibodies to N. lactamica and N. meningitidis NG:4:- but not to capsulate isolates: B:4:P1.15; B:15:P1.16; B:4:-; C:4:-. Bactericidal activity was higher for both carriers and secretors but the differences were not significant. Bactericidal activity was not associated with total or specific IgA or IgM. Carriers had significantly higher levels of IgG to N. lactamica but not to NG:4:- in sera with bactericidal activity for each of the capsulate strains. Among non-carriers, higher levels of IgG to N. lactamica were associated with killing of B:4:P1.15 and B:4:-. Secretors' sera with bactericidal activity had significantly higher levels of IgG to N. lactamica compared with sera that were not bactericidal. This was not observed among non-secretors. Antibodies to the outbreak strain were adsorbed by all Neisseria isolates tested and absorption of sera with N. lactamica alone completely removed the bactericidal activity against the outbreak strain.     

The immunological status indices of monkeys inoculated with a meningococcal B vaccine

The method for the determination of bacterial antibodies to group B meningococci was worked out. The method was used for the determination of antibodies to group B meningococcal vaccine produced in the USSR. The dynamic study of antibodies to protein, polysaccharide and lipopolysaccharide antigens of group B meningococci was made by the method of the enzyme immunoassay (EIA), and the safety of the vaccine was studied by the determination of autoantibodies active against brain tissue antigens. The data thus obtained were indicative of the immunological activity of group B protein-polysaccharide vaccines, manifested by the capacity for stimulating bactericidal antibodies whose level increased 8- to 10-fold after the immunization of monkeys in 2 and 3 injections. Similarity in the dynamics of the formation of bacteriolysins and antibodies to protein antigen, as determined in EIA, was noted. The vaccine was found to stimulate no cytotoxic anticerebral antibodies in the glia migration test, which was indicative of the safety of group B meningococcal vaccine.     

Control of meningococcal meningitis with meningococcal vaccines.

The development of effective meinigococcal vaccines was based upon the finding that immunity to the meningococcus was directly correlated with serum bactericidal antibodies. Purified high molecular weight capsular polysaccharides of serogroups A and C meningococci stimulated the production of humoral antibodies which had group specific bactericidal activity. In controlled field trials in Army recruits, group C polysaccharide vaccines were highly effective in preventing group C disease. Following its use as a routine immunization in recruits in October 1971 group C meningococcal disease has been almost completely eliminated from Army training centers. Group A vaccine has been field tested in Egyptian school children with great success. Group B polysaccharide has failed to induce bactericidal antibodies in humans and, therefore, new research is underway to attempt to develop a cell wall protein antigen as a vaccine against group B disease.     

Measurement of opsonophagocytic activity of antibodies specific toNeisseria meningitidis serogroup A capsular polysaccharide-serogroup B outer membrane vesicle conjugate in animal model

Neisseria meningitidis is efficiently phagocytosed by polymorphonuclear leukocytes (PMNS) following opsonization with opsonic antibodies; opsonophagocytosis is the primary mechanism for clearance of meningococci from the host. Thus, in testing meningococcal vaccines, the level of opsonophagocytic antibodies appears to correlate with vaccine-induced protection. Our previous studies demonstrated that the conjugation ofN. meningitidis serogroup A capsular polysaccharide (CPSA) to serogroup B outer membrane vesicle (OMV) could induce a high level of bactericidal antibody response against serogroup A meningococci in animals. The purpose of this study was to evaluate opsonophagocytic activity of the conjugate of CPSA to OMV (CPSA-OMV). In order to evaluate the potential efficacy of CPSA-OMV a flow cytometric opsonophagocytic assay was used. The conjugate and controls were injected intramuscularly into four groups of rabbits with boosters on days 14, 28 and 42 following primary immunization. The rabbits were bled prior to injection and two weeks after each injection. Opsonophagocytic activity of antibodies in hyperimmune sera through rabbit PMNS were measured with flow cytometer, using dihydrorhodamine-123 as a probe. The results indicated that our conjugate could induce a highly significant level of opsonophagocytic activity against serogroup A meningococci after 56 days compared to the control groups (P<0.05). We conclude that this conjugate represents a vaccine candidate against serogroups A and B meningococci after further investigation.     

Murine typhus on the northern Dalmatian islands, Yugoslavia

The present epidemiological study had the objective to establish whether and to what extent resident islander populations might be affected by the natural foci of murine typhus. To this end, 294 serum specimens were collected during summer and autumn of 1985 from the northern Dalmatian islanders, all of which were tested for anti-Rickettsia typhi (R. typhi) complement fixing (CF) antibodies. These were detected and confirmed at both stages of the screening, namely during the first stage, conducted on the northern Dalmatian islands, where 63.3% of the representative population had a titre of 1:4 or higher and during the second stage, carried out on the island of Vir, with 68.1% of the residents found R. typhi positive unlike in the former. The majority of positive sera were found in the 21-60-year group, peaking in the 21-30- and 31-40-year groups with fewer positive sera among the subjects over 60 and the fewest among the residents below 20 years of life. Thus, current differences in antibody rates in various age groups were shown to be statistically significant. Murine typhus immunity in resident islander populations could be detected from the age of 10 years on, and was shown to become almost equal to the adult population's positive sera levels in the 16-20-year age group. No differences were revealed with regard to the infective agent exposure between the male and female populations representative of the total population or in any of the age groups.     

The bactericidal action of human neutrophils on meningococci in vitro

32 Russian patients with late complement component deficiency (LCCD) were immunize with tetravalent meningococcal polysaccharide vaccine (A + C + W135 + Y). Their immune response and infectious morbidity rate were followed for 6 years and the partial protective efficacy of vaccination was demonstrated. As the antibody-mediated complement-induced bactericidal activity of plasma was completely absent in persons with LCCD, the bactericidal action of human neutrophils on meningococci of groups A, W135 and B was studied under the conditions of incubation with serum samples collected from persons with LCCD before and after vaccination. In LCCD serum alone the exponential growth of meningococci was observed, while the addition of human neutrophils resulted in the essential inhibition of the growth of meningococci (up to their complete elimination). The proportion of serum samples stimulating the elimination of group A and W 135 meningococci by neutrophils was almost 40% of the serum samples collected before vaccination and significantly increased among the serum samples collected after vaccination (up to 84%) or revaccination (up to 90%). At the same time the capacity of an individual serum sample to promote the bactericidal effect of neutrophils against meningococci correlated with its content of specific anti-polysaccharide IgG and IgM antibodies, as well as antibodies to the inner core of lipopolysaccharide. The interaction of neutrophils with meningococci was significantly inhibited after incubation in heat-inactivated serum, suggesting that this interaction was partly mediated along the following path: the binding of IgM and IgG antibodies with bacteria--the activation of complement and the deposition of C3 complement on bacteria--the binding of meningococci with CR3 receptors of neutrophils.     

Antibody response to capsular polysaccharide antigen in an infection caused by meningococcus serogroup B in children

The continuous synchronous cultivation of serogroup B meningococci and the use of the selected clones of producer strains has made it possible to obtain the serologically active preparation of the group-specific antigen from the culture in the exponential phase. The erythrocyte diagnosticum produced on the basis of this preparation has permitted the detection of group-specific antibodies in the sera of immunized rabbits and children with generalized infection caused by serogroup B meningococci. The intensity of immune response depends on the age of children. This new technique of the passive hemagglutination test is recommended for the confirmation of generalized infection caused by serogroup B meningococci.     

Serologic pattern of meningococci in a focus of infection]

The authors present the results of typing of meningococci (isolated from the patients and carriers) by the sera of serological groups A, B, C, D, X, Y, and Z made at the Leningrad Institute of Vaccine and Sera. The causative agents of serological group A were most frequently isolated from the patients with the generalized forms of meningococcus infection. The percentage of detection of meningococci of serological group A was the greatest in the patients and much less in the carriers in and outside the foci of this infection. Many dissociated cultures were revealed among the strains isolated from the carriers. Sera of the Leningrad Institute of Vaccine and Sera have permitted typing of meningococci cultures belonging to various serological groups in accordance with the international classification.     

Prevalence of Leptospira and Brucella antibodies in wild boars (Sus scrofa) in Tuscany, Italy

Five hundred sixty-two blood samples were collected from wild boars (Sus scrofa) shot in six districts of Tuscany, central Italy, between 1997 and 2000. Sera were examined for antibodies specific for Leptospira interrogans by microagglutination test and Brucella spp. by the Rose Bengal test and indirect enzyme-linked immunosorbent assay. Thirty-four (6.0%) samples tested positive for anti-Leptospira antibodies, 29 (5.1%) sera were positive for anti-L. interrogans serovar bratislava antibodies (titres ranging from 1:100-1:400), and 5 (0.9%) sera were positive for anti-L. interrogans serovar icterohaemorrhagiae antibodies (titres 1:100). All the examined sera were negative for anti-Brucella antibodies.     

The evolution of meningococcal infection in Mongolia]

On the basis of the generalization and analysis of the results of bacteriological and immunological investigations the epidemic process of meningococcal infection (MI) in Mongolia was found to undergo definite changes during the last 20 years. Group A meningococci prevailing in the etiology of MI were replaced by strains belonging to group B affecting mainly young children (aged up to 3 years). MI morbidity rate caused by group B meningococci was found to be higher in Mongolia than in other countries of the world. These data substantiate the necessity of using more effective remedies for the control of this infection and, in particular, specific immunization with vaccines against group B meningococci; profound study of the properties of the circulating meningococcal strains is to be carried out.     

2007年重庆市流脑流行季节前健康人群抗体水平和带菌率调查

为了解重庆市流脑流行季节前健康人群免疫水平和带菌状况,预测发病趋势,提出新的免疫策略,提供有效的预防措施。按照全国流脑监测方案并结合重庆市2006年流脑疫情情况,选择重庆市北碚区、长寿区和万盛区为2007年流脑监测点,采集0~、5~、10~、15~、25~、35~及45岁以上共7个年龄组人群的静脉血和咽拭子,分别进行抗体水平和带菌率检测。结果显示,重庆市健康人群A群流脑IgG抗体的阳性率为76.02%(485/638),C群流脑IgG抗体的阳性率为47.65%(304/638),健康人群脑膜炎奈瑟菌(简称Nm)带菌率为0.47%(3/638)。重庆市健康人群A群流脑IgG抗体阳性率维持在较高水平,而C群流脑IgG抗体的阳性率较低,提示该市大部分人群对A群流脑有免疫作用,但C群抗体水平较低,有引起局部流脑爆发的风险。     

The etiological structure of acute bacterial meningitis in different regions]

In 1985-1989 the etiological structure of acute bacterial meningitides (ABM) in children was studied in 4 largest industrial cities in different regions of the European part of the former USSR, as well as in 2 industrial cities of western Siberia. Due to the common methodological approach used in all investigations, comparable data were obtained in all cities. These investigations revealed that meningococci caused 53.0-86.7% of all cases of ABM in children, which corresponded to moderately increased morbidity rate in meningococcal infection (3.9-11.0 cases per 100,000 of the population, mostly 5.0-7.0 cases) in these cities with its progressive decrease during 3-4 years of observation. The gradual change of meningococci from group A, prevailing in the '70s and early '80s, to group B and in some cases the appearance of group C meningococci, accompanied by a decrease in morbidity rate, were noted. In St. Petersburg the indices of ABM morbidity in children aged up to 5 years for 1987 and 1988, caused by Haemophilus influenzae (0.74 and 4.13) and pneumococci (3.23 and 4.86), could be calculated. A great number of ABM cases of unclear etiology (15.9-33.3%) suggests that the number of ABM cases caused by these two infective agents was underestimated.     

Immunogenicity and evolutionary variability of epitopes within IgA1 protease from serogroup A Neisseria meningitidis

Five murine epitopes were defined and mapped within IgA1 protease produced by Neisseria meningitidis. Epitopes 1 and 2 were present in IgA1 protease from all strains, and from Neisseria gonorrhoeae. Epitopes 3 through to 5 varied between subgroups of serogroup A meningococci. but have remained constant over decades within the subgroups, except for epitope 4, which changed between 1983 and 1987 during the spread of subgroup III meningococci from Asia to Africa. Binding of monoclonal antibodies to epitopes 1, 4 and 5 neutralized enzymatic function. Human sera containing antibodies to lgA1 protease as a result of natural infection inhibited binding of monoclonal antibodies to epitope 4 but not to the other epitopes.     

Serum antibodies to whole-cell and recombinant antigens of Borrelia burgdorferi in cottontail rabbits

Archived serum samples, from 95 eastern cottontail rabbits (Sylvilagus floridanus) captured in New York, New York, USA and Millbrook, New York, USA, during 1985-86, were analyzed in solid-phase enzyme-linked immunosorbent assays (ELISA) for total and class-specific immunoglobulin (Ig) M antibodies to whole-cell or recombinant antigens of Borrelia burgdorferi sensu stricto. Using a polyvalent conjugate, rabbit sera contained antibodies to whole-cell and recombinant antigens (protein [p]35, p37, or VlsE) during different seasons, but there was no reactivity to outer surface protein (Osp)A or OspB. Seventy-six of the 102 sera (75%) analyzed were reactive with one or more of the antigens; 61 of the positive samples (80%) reacted to whole-cell antigens, followed by results for the p35 (58%, 44/76), VlsE (43%, 33/76), and p37 (29%, 22/ 76) antigens. Fifty-eight sera (76%) contained antibodies to the VlsE or p35 antigens with or without reactivity to whole-cell antigens. High antibody titers (≥1:2,560) recorded for 52 sera indicate robust antibody production. In analyses for IgM antibodies in an ELISA containing whole-cell antigens, there were 30 positive sera; titers ranged from 1:160 to 1:640. There was minimal cross-reactivity when rabbit antisera to Treponema pallidum or four serovars of Leptospira interrogans were screened against B. burgdorferi antigens. Based on more-specific results, VlsE and p35 antigens appear to be useful markers for detecting possible B. burgdorferi infections.     

Frequency and potential application of HLA antibodies from pregnant women in Mumbai

Antenatal sera from 1334 pregnant women attending the Nowrojee B J Wadia Maternity Hospital and KEM Hospital in Parel, Mumbai were collected and screened for anti HLA A and B antibodies to produce an indigenous HLA tissue typing tray. One hundred and sixty three sera (12.2%) were found positive for HLA antibodies. Nonetheless, the percentage of positive sera were almost the same in women of different parity. Moreover, the incidence of anti-HLA antibodies was correlated with the allelic frequencies in the Maharastrian population. Thus in India, collection and screening of sera from pregnant females is a simple and cost-effective method of acquiring polyclonal sera for routine use in tissue typing.     

Frequency of HLA antibodies in south India

Sera from 4088 pregnant women (649 antenatal bleeding and 3439 post-partum bleeding) living in Madurai, were collected and screened for anti-HLA. A, B and DR antibodies. 696 of them were screened for anti-HLA DR antibodies. Ten per cent (65/649) of antenatal sera and 13 4% of post-partum sera (463/3439) were positive for HLA A and B antibodies: nonetheless the percentage of monospecific sera were almost the same in both. Screening for HLA DR antibodies were carried out using platelet absorption in test tray technique: seventy three of 696 (10.5%) were positive. The incidence of anti-HLA A, B antibodies correlates to the allelic frequencies in the population. Thus in India, collection and screening post-partum haemorrhage is the simplest and cost effective method of acquiring polyclonal sera for routine laboratory and diagnostic use.