Meningococcal serogroup B vaccine (4CMenB): Booster dose in previously vaccinated infants and primary vaccination in toddlers and two-year-old children

OBJECTIVE

The multicomponent, recombinant serogroup B vaccine, 4CMenB, is approved in Europe, Canada and Australia from two months of age. We investigated persistence to booster doses at 12 months of age following infant vaccination, and immune response to catch-up vaccination of toddlers and children up to two years of age.

METHODS

We assessed persistence of immune responses after one year in participants vaccinated as infants, and responses to two doses at 12-15 or 24-26 months of age in vaccine-naïve children, as serum bactericidal activity with human complement (hSBA) against indicator strains for four vaccine antigens. Adverse events were recorded after each vaccination.

RESULTS

High antibody titers were induced against all four 4CMenB components following booster vaccination in infant-primed toddlers and after two doses in previously unvaccinated toddlers or two-year-olds. Antibodies waned over 12 months, particularly those against NZ OMV. Systemic reactogenicity in toddlers was lower than in infants, and lower again in vaccine-naïve two-year-olds. Local reactogenicity was common in all groups.

CONCLUSIONS

Four infant or two toddler 4CMenB vaccinations elicit immune responses believed to be protective for the first two years of life, which can be boosted. Reactogenicity is lower in toddlers than in infants.

A phase 2 randomized controlled trial of a multicomponent meningococcal serogroup B vaccine (I)

The novel meningococcal serogroup B vaccine (4CMenB, Bexsero(®)), recently approved in Europe and Australia, may soon be included in routine infant immunization schedules, subject to guidance from national or regional recommending bodies. In the development of 4CMenB and consistent with other newly introduced vaccines, clinical studies have shown concomitant administration with routine infant vaccines induces an incremental increase in some reactions, including fever. As this may hinder acceptability, we examined the impact of prophylactic paracetamol on the occurrence of fever and other solicited reactions, as well as the immune responses to study vaccines, in a prospectively designed study. 4CMenB was administered as a 4-dose series at 2, 3, 4, and 12 months of age concomitantly with routine infant vaccines: DTaP-HBV-IPV/Hib and PCV7, with or without prophylactic paracetamol; a third group received MenC vaccine. Immune responses to 4CMenB were not decreased by the use of paracetamol prophylaxis and there were no clinically relevant effects on immune responses to routine vaccines. Occurrence of fever was higher in infants co-administered with 4CMenB compared with those given MenC vaccine, but was significantly decreased by prophylactic paracetamol, as were other solicited reactions to vaccination, both local and systemic. Co-administration of 4CMenB had an acceptable tolerability profile, with no withdrawals due to vaccination-related adverse events. Inclusion of 4CMenB in routine infant immunization schedules will be a major advance in the control of meningococcal disease, and our study indicates that by using paracetamol prophylaxis, post-vaccination reactions are reduced without clinically relevant negative consequences on vaccine immunogenicity.

Immunogenicity and safety of an investigational multicomponent, recombinant, meningococcal serogroup B vaccine (4CMenB) administered concomitantly with routine infant and child vaccinations: results of two randomised trials

BACKGROUND

Meningococcal serogroup B disease disproportionately affects infants. We assessed lot-to-lot consistency, safety and immunogenicity, and the effect of concomitant vaccination on responses to routine vaccines of an investigational multicomponent vaccine (4CMenB) in this population.

METHODS

We did primary and booster phase 3 studies between March 31, 2008, and Aug 16, 2010, in 70 sites in Europe. We used two series of sponsor-supplied, computer-generated randomisation envelopes to allocate healthy 2 month-old infants to receive routine vaccinations (diphtheria-tetanus-acellular pertussis, inactivated poliovirus, hepatitis B plus Haemophilus influenzae type b, and seven-valent pneumococcal vaccine) at 2, 4, and 6 months of age alone, or concomitantly with 4CMenB or serogroup C conjugate vaccine (MenC) in: 1) an open-label, lot-to-lot immunogenicity and safety substudy of three 4CMenB lots compared with routine vaccines alone (1:1:1:1, block size eight); or 2) an observer-blind, lot-to-lot safety substudy of three 4CMenB lots compared with MenC (1:1:1:3, block size six). At 12 months, 4CMenB-primed children from either substudy were randomised (1:1, block size two) to receive 4CMenB booster, with or without measles-mumps-rubella-varicella (MMRV) vaccine. Immunogenicity was assessed by serum bactericidal assay with human complement (hSBA) against serogroup B test strains, and on randomly selected subsets of serum samples for routine vaccines; laboratory personnel were masked to assignment. The first coprimary outcome was lot-to-lot consistency (hSBA geometric mean ratio of all lots between 0·5 and 2·0), and the second was an immune response (hSBA titre ≥5) for each of the three strains. The primary outcome for the booster study was immune response to booster dose. Immunogenicity data for 4CMenB were for the modified intention-to-treat population, including all infants from the open-label substudy who provided serum samples. The safety population included all participants who contributed safety data after at least one dose of study vaccine. These trials are registered with ClinicalTrials.gov, numbers NCT00657709 and NCT00847145.

FINDINGS

We enrolled 2627 infants in the open-label phase, 1003 in the observer-blind phase, and 1555 in the booster study. Lot-to-lot consistency was shown for the three 4CMenB lots, with the lowest 95% lower confidence limit being 0·74 and the highest upper limit being 1·33. Of 1181–1184 infants tested 1 month after three 4CMenB doses (all lots pooled), 100% (95% CI 99–100) had hSBA titres of 5 or more against strains selective for factor H binding protein and neisserial adhesin A, and 84% (82–86) for New Zealand outer-membrane vesicle. In a subset (n=100), 84% (75–91) of infants had hSBA titres of 5 or more against neisseria heparin binding antigen. At 12 months of age, waning titres were boosted by a fourth dose, such that 95–100% of children had hSBA titres of 5 or more for all antigens, with or without concomitant MMRV. Immune responses to routine vaccines were much the same with or without concomitant 4CMenB, but concomitant vaccination was associated with increased reactogenicity. 77% (1912 of 2478) of infants had fever of 38·5°C or higher after any 4CMenB dose, compared with 45% (295 of 659) after routine vaccines alone and 47% (228 of 490) with MenC, but only two febrile seizures were deemed probably related to 4CMenB.

INTERPRETATION

4CMenB is immunogenic in infants and children aged 12 months with no clinically relevant interference with routine vaccines, but increases reactogenicity when administered concomitantly with routine vaccines. This breakthrough vaccine offers an innovative solution to the major remaining cause of bacterial meningitis in infant and toddlers.

FUNDING

Novartis Vaccines and Diagnostics.

[Immunogenicity of vaccines against viral hepatitis A and B in the population above 40 years of age -- impact of risk factors]

The immune reaction following vaccination against viral hepatitis A (HAV) and viral hepatitis B (HBV) can be influenced by a variety of factors. Among the most important are age, gender and body weight.

STUDY OBJECTIVE

This prospective randomized study compared immunogenicity of available vaccines against HAV and HBV infections in the population above 40 years of age and the impact of risk factors.

MATERIAL AND METHODS

The vaccinated subjects were divided into 3 groups based on the vaccine used. Within each group, the subjects were equally distributed by age, gender and body weight. The vaccine was always applied intramuscularly in the deltoid. Group 1 was given the combined vaccine Twinrix (GSK) against HAV and HBV infections in the left deltoid; group 2 was vaccinated with the Havrix vaccine against HAV (GSK) in the right deltoid and with the Engerix-B vaccine against HBV (GSK) in the left deltoid; group 3 received the Vaqta vaccine against HAV (Sanofi Pasteur) in the right deltoid and the HB VAX PRO against HBV (Sanofi-Pasteur) in the left deltoid.

RESULTS

The following anti-HBs seroprotectivity rates: 92%, 80% and 71%, and anti-HAV seropositivity rates: 97%, 99% and 99%, were observed at 1 month after the end of the complete vaccination in groups 1, 2 and 3, respectively. The anti-HBs seroprotectivity rate was statistically significantly higher in group 1. The anti-HAV seropositivity rates were comparable (did not significantly differ) in all three study groups.

CONCLUSION

The impact of age was revealed: the immune response decreases with increasing age. The lowest immunogenicity of the vaccines against HAV and HBV infections was observed in subjects above 60 years of age. Males achieved lower geometric mean titres (GMT) of antibodies and lower seroprotectivity rates compared to females. The impact of body weight was also observed, with the obese subjects showing the lowest immune response. The anti-HBs reactivity was significantly influenced by the vaccine used. The combined vaccine against HAV and HBV infections (Twinrix) induced higher anti-HBs seroprotectivity and comparable anti-HAV seropositivity when compared with the other monovalent study vaccines in the population above 40 years of age.

The immunogenicity and reactogenicity of a new DTPw-HBV vaccine as a primary and booster vaccination course in healthy infants

The immunogenicity and reactogenicity of primary vaccination at 3, 4 and 5 months and boosting at 12-18 months with a new DTPw-HBV vaccine was compared with either licensed DTPw and HBV vaccines given separately or a licensed DTPw-HBV combination (Tritanrix-HepB) in this randomized, partially double-blind primary vaccination and single-blind booster vaccination study in healthy infants (n = 239; Trial DTPw-HBV-001/004). One month after primary vaccination with the new DTPw-HBV vaccine, seroprotection against diphtheria, tetanus, hepatitis B and vaccine response to B. pertussis was seen in 100%, 98.7%, 94.9% and 98.7% of subjects, respectively, compared to 100%, > or =98.5%, 89.2% and 92.2% of subjects in the comparator groups, respectively. One month after the booster dose, a marked response to all vaccine antigens was observed, resulting in seroprotection against diphtheria, tetanus, hepatitis B in all DTPw-HBV recipients and response to B. pertussis in over 98.6%. After primary vaccination, there was evidence that fever > or =38.0 degrees C (rectal route) occurred more frequently after the new vaccine (following 41.6% of doses, compared with 32.2% and 29.3% in the comparator groups, p < 0.05) and that pain and drowsiness occurred more frequently than after licensed DTPw-HBV (45.3% versus 35.1% and 37.1% versus 24.9%, respectively). However after primary and booster doses Grade 3 symptoms occurred at similar frequencies in the three groups suggesting these possible differences are of minimal clinical significance. In conclusion, within the framework of this study the immunogenicity and safety profiles of GSK Biologicals' new DTPw-HBV vaccine when used for primary and booster vaccination were acceptable.

Long-term protective effect of post-exposure Havrix administration during viral hepatitis Type A outbreaks

Administration of human normal immunoglobulin (HNIG) post-exposure has been routinely used in Slovakia for outbreak control of hepatitis A, but requires deep intramuscular injection, provides only short-lived protection and is a human blood product. The protective effect of post-exposure administration of an inactivated hepatitis A vaccine was evaluated during 10 outbreaks in Slovakia. Direct contacts of confirmed hepatitis A cases received either: a single dose of hepatitis A vaccine (n = 2171) or immunoglobulin (HNIG, n = 3837). In the HNIG group the number of hepatitis A confirmed cases dropped within the first 7 weeks, however the decrease was not as rapid or as marked as that observed in the vaccinated group where the number of hepatitis A cases dropped within the first 4 weeks after vaccination. Among contacts, 67 cases of hepatitis A were detected during the maximum incubation period of 45 days: 16 cases (0.7%) in the vaccine group and 51 cases (1.3%) in the HNIG group (p < 0.05). After two and three years respectively, 50 and 39 volunteers who had previously received one dose of hepatitis A vaccine received a booster dose and anti-HAV antibodies were measured. Differences in anti-HAV antibody GMCs before and after the booster were statistically significant. The longer time interval (3 years instead of 2) between primary vaccination and booster administration did not seem to impact the magnitude of the booster response. The results of this study show that active post-exposure immunisation with only one dose of inactivated vaccine confers high and long-term protection and effectively controls viral hepatitis A outbreaks.

The local and intermediate range structures of the five amorphous ices at 80K and ambient pressure: A Faber-Ziman and Bhatia-Thornton analysis

Using isotope substitution neutron scattering data, we present a detailed structural analysis of the short and intermediate range structures of the five known forms of amorphous ice. Two of the lower density forms--amorphous solid water and hyperquenched glassy water--have a structure very similar to each other and to low density amorphous ice, a structure which closely resembles a disordered, tetrahedrally coordinated, fully hydrogen bonded network. High density and very high density amorphous ices retain this tetrahedral organization at short range, but show significant differences beyond about 3.1 A from a typical water oxygen. The first diffraction peak in all structures is seen to be solely a function of the intermolecular organization. The short range connectivity in the two higher density forms is more homogeneous, while the hydrogen site disorder in these forms is greater. The low Q behavior of the structure factors indicates no significant density or concentration fluctuations over the length scale probed. We conclude that these three latter forms of ice are structurally distinct. Finally, the x-ray structure factors for all five amorphous systems are calculated for comparison with other studies.

[Seroprevalence of antibodies against hepatitis A virus and hepatitis B virus in nonvaccinated adult population over 40 years of age]

STUDY OBJECTIVE

To determine prevalence rates of antibodies against hepatitis A virus (HAV) and hepatitis B virus (HBV) in the general adult male and female population over 40 years of age with no history of viral hepatitis A (VHA) and viral hepatitis B (VHB) who have never been vaccinated against hepatitis and to assess the cost-effectiveness of the pre-vaccination serological screening.

MATERIAL AND METHODS

In 2003-2004, a total of 972 persons of three age categories: 41-50 years, 51-60 years, 61 and more years, were screened. Persons with a history of VHA and/or VHB and those who had been vaccinated against hepatitis were not included in the study. The following four indicators were determined from a 5 ml specimen of whole venous blood by electrochemiluminiscence assay: total anti-HAV antibodies, total anti-HBc antibodies, anti-HBs antibodies and HBsAg, as the most suitable markers of experienced hepatitis or previous vaccination.

RESULTS

The prevalence rates of anti-HAV antibodies were lower in females compared to males for all of the three age categories. These antibodies were detected in 16.8%, 52.9% and 77.5% of 41-50-year-olds, 51-60-year-olds and > or = 61-year-olds, respectively. The total prevalence rate for the three age groups was 61.6%. The anti-HBc antibody seroprevalence rates were 1.9%, 5.3% and 6.1%, respectively.

CONCLUSION

The results show high prevalence of VHA in higher age groups. Such a high seroprevalence of antibodies in nonvaccinated persons with no history of viral hepatitis is suggestive of a very frequent incidence of asymptomatic infection. For this reason, the prevaccination screening of anti-HAV antibodies is cost-effective in the population over 50 years of age but is not justified in persons under 40 years of age. Prevaccination screening for anti-HBc antibodies appears not to be cost-effective regardless of age in view of their low prevalence in the Czech population.

[Human papillomavirus and carcinoma of the cervix vaccines against the human papillomavirus-promise of an efficacious prevention]

The persistent infection with high-risk (oncogenic) HPV types is the necessary cause of cervical cancer. HPV types 16 and 18 are the most important of the high-risk types all around the world. The low risk HPV types, include type 6, 11 and next, cause either benign genital warts or low-grade intraepithelial lesions. Cervical cancer is the third most important cause of cancer deaths in women worldwide, after, first, breast cancer and, second, lung cancer, and the leading cause of cancer deaths in women in the developing world. Every year, half a million women around the world are diagnosed as new cases, and more than 270,000 die from this disease. The majority of deaths, around 80 %, occur in developing countries (in Latin America and Sub-Saharan Africa). The main reason for these variations in incidence is probably the availability of screening programmes in many developed countries but not in poorer developing countries. Pap smear testing forms the basis of cervical cancer screening programmes round the world. A well-implemented screening programme can reduce the incidence of cervical cancer in a country by approximately 80 %. Although useful is fully implemented, a cytology-based screening programme does have limitations. It cannot prevent infection with high-risk HPV or the subsequent development of pre-cancerous lesions. It is also a very expensive and demanding system to set up and maintain. Knowledge that cervical cancer is caused by viral infection provided the exceptional way to use a vaccination as the next tool of cervical cancer prevention. There are the only two realistic approaches for the prevention of cervical cancer--cervical screening and vaccination. Vaccination of a healthy individual to protect them against a disease is an excellent example of primary prevention. Two pharmaceutical companies--GlaxoSmithKline (GSK) and Merck--developed a prophylactic vaccines which are already in the pre-licence phase. The results published up to now showed a high efficacy and good safety profile of vaccines, and were well tolerated.

Pneumococcal capsular polysaccharides conjugated to protein D for prevention of acute otitis media caused by both Streptococcus pneumoniae and non-typable Haemophilus influenzae: a randomised double-blind efficacy study

BACKGROUND

Acute otitis media is one of the most commonly-diagnosed childhood infections. This study assessed the efficacy of a novel vaccine that contained polysaccharides from 11 different Streptococcus pneumoniae serotypes each conjugated to Haemophilus influenzae-derived protein D in prevention of acute otitis media.

METHODS

4968 infants were randomly assigned to receive either pneumococcal protein D conjugate or hepatitis A vaccine at the ages of 3, 4, 5, and 12-15 months and were followed-up until the end of the second year of life. Middle-ear fluid was obtained for bacteriological culture and serotyping in children who presented with abnormal tympanic membrane or presence of middle-ear effusion, plus two predefined clinical symptoms. The primary endpoint was protective efficacy against the first episode of acute otitis media caused by vaccine pneumococcal serotypes. Analysis was per protocol.

FINDINGS

From 2 weeks after the third dose to 24-27 months of age, 333 clinical episodes of acute otitis media were recorded in the protein D conjugate group (n=2455) and 499 in the control group (n=2452), giving a significant (33.6% [95% CI 20.8-44.3]) reduction in the overall incidence of acute otitis media. Vaccine efficacy was shown for episodes of acute otitis media caused by pneumococcal vaccine serotypes (52.6% [35.0-65.5] for the first episode and 57.6% [41.4-69.3] for any episode). Efficacy was also shown against episodes of acute otitis media caused by non-typable H influenzae (35.3% [1.8-57.4]). The vaccine reduced frequency of infection from vaccine-related cross-reactive pneumococcal serotypes by 65.5%, but did not significantly change the number of episodes caused by other non-vaccine serotypes.

INTERPRETATION

These results confirm that using the H influenzae-derived protein D as a carrier protein for pneumococcal polysaccharides not only allowed protection against pneumococcal otitis, but also against acute otitis media due to non-typable H influenzae. Whether this approach would also allow improved protection against lower respiratory tract infections warrants further investigation.

Structures of high and low density amorphous ice by neutron diffraction

Neutron diffraction with isotope substitution is used to determine the structures of high (HDA) and low (LDA) density amorphous ice. Both "phases" are fully hydrogen bonded, tetrahedral networks, with local order similarities between LDA and ice Ih, and HDA and liquid water. Moving from HDA, through liquid water and LDA to ice Ih, the second shell radial order increases at the expense of spatial order. This is linked to a fifth first neighbor "interstitial" that restricts the orientations of first shell waters. This "lynch pin" molecule which keeps the HDA structure intact has implications for the nature of the HDA-LDA transition that bear on the current metastable water debate.

Control of laser high-harmonic generation with counterpropagating light

Relatively weak counterpropagating light is shown to disrupt the emission of laser high-harmonic generation. Harmonic orders ranging from the teens to the low thirties produced by a 30-femtosecond pulse in a narrow argon jet are "shut down" with a contrast as high as 2 orders of magnitude by a chirped 1-picosecond counterpropagating laser pulse (60 times less intense). Alternatively, under poor phase-matching conditions, the counterpropagating light boosts harmonic production by similar contrast through quasiphase matching where out-of-phase emission is suppressed.

Inverse correlation between IgG-antihinge region and antierythrocyte autoantibody in chronic benign and malignant cold agglutination

Previous reports provided evidence of an immunosuppressive role of natural anti-F(ab')2 antibodies. If suppressive anti-F(ab')2 antibodies also regulated the autoantibody production in cold agglutination, one would expect high titers of anti-F(ab')2 to be associated with low titers of cold agglutinins. Indeed, our previous studies revealed an inverse correlation between IgG-anti-F(ab')2 and cold agglutinins. Many previous experiments focused on anti-F(ab')2 of an antiidiotypic nature. Recent epitope mapping showed that anti-F(ab')2 of healthy persons is not an antiidiotype but recognizes a hinge region sequence. We attempted to answer the question whether this IgG-antihinge antibody is responsible for the previously described association between anti-F(ab')2 and cold agglutinins. IgG-antihinge and IgG-anti-F(ab')2 antibody was determined and statistically analyzed in the serum of 334 patients with cold agglutination. Our experiments revealed a strong correlation between the concentrations of antihinge and the previously described anti-F(ab')2 antibody. The anti-F(ab')2 activity was competitively inhibited by a synthetic hinge peptide. Moreover, patients with high antihinge titers had low cold agglutinin titers, and vice versa. A stratification according to cold agglutinin specificity and disease etiology showed that the inverse correlation is present only in anti-I and anti-i patients suffering from monoclonal B-lymphocyte proliferation. In conclusion, our results confirm the correlation previously described for anti-F(ab')2 antibody and antierythrocyte autoantibody and define for the first time an association between an idiotype-independent anti-IgG autoantibody and cold agglutinin.

A natural IgA-anti-F(ab')2gamma autoantibody occurring in healthy individuals and kidney graft recipients recognizes an IgG1 hinge region epitope

Natural anti-IgG autoantibodies are found both in healthy individuals and in patients with certain diseases. One group of these Abs recognizes epitopes located in the F(ab')2 region of the IgG molecule. The immunoregulatory role of these Abs in healthy individuals, graft rejection, and disease was previously studied, usually with a focus on the characterization of anti-idiotypic Abs. In the present study, we characterize the epitope recognized by an anti-F(ab')2gamma autoantibody of the IgA isotype, which occurs in the serum of healthy individuals and kidney transplant recipients. The autoantibody described herein reacts strongly with F(ab')2gamma but only poorly with Fab(gamma) fragments, a binding pattern pointing to an epitope located in the hinge region. Using synthetic peptides, we identified a conformational epitope that overlaps the middle and part of the lower hinge region. Structural analyses of peptide constructs showed that a defined conformation of the first three residues of the lower hinge is required for a full expression of the epitope. Binding of IgA to the hinge region of IgG1 covers part of the physiologically active Fc domain, immobilizes the Fab arms, and thereby can be expected to exert immunoregulatory functions.

A natural IgA-anti-F(ab')2gamma autoantibody occurring in healthy individuals and kidney graft recipients recognizes an IgG1 hinge region epitope

Natural anti-IgG autoantibodies are found both in healthy individuals and in patients with certain diseases. One group of these Abs recognizes epitopes located in the F(ab')2 region of the IgG molecule. The immunoregulatory role of these Abs in healthy individuals, graft rejection, and disease was previously studied, usually with a focus on the characterization of anti-idiotypic Abs. In the present study, we characterize the epitope recognized by an anti-F(ab')2gamma autoantibody of the IgA isotype, which occurs in the serum of healthy individuals and kidney transplant recipients. The autoantibody described herein reacts strongly with F(ab')2gamma but only poorly with Fab(gamma) fragments, a binding pattern pointing to an epitope located in the hinge region. Using synthetic peptides, we identified a conformational epitope that overlaps the middle and part of the lower hinge region. Structural analyses of peptide constructs showed that a defined conformation of the first three residues of the lower hinge is required for a full expression of the epitope. Binding of IgA to the hinge region of IgG1 covers part of the physiologically active Fc domain, immobilizes the Fab arms, and thereby can be expected to exert immunoregulatory functions.

Family outbreak of alimentary tick-borne encephalitis in Slovakia associated with a natural focus of infection

A family outbreak of tick-borne encephalitis involving 7 people, all of them hospitalized, was observed in the district of Povazská Bystrica (central Slovakia). The disease was associated with the drinking of unboiled goat milk and tick-borne encephalitis virus was recovered from Ixodes ricinus ticks collected from places where goats were grazing.

The natural human IgG anti-F(ab')2 antibody recognizes a conformational IgG1 hinge epitope

Natural IgG anti-F(ab')2 Abs are part of the physiologic immune repertoire and have important immunoregulatory functions. Although previous work suggested that some of these Abs recognize epitopes located in the constant region of the F(ab')2 molecule, an exact epitope mapping has not been performed. We found that the anti-F(ab')2 Ab binds strongly to F(ab')2 but only weakly to Fab fragments. Fab fragments are lacking the core and lower hinge region. In our experiments, we show that the IgG anti-F(ab')2 Ab binds strongly to a synthetic double chain peptide (225-237/225'-237') comprising the core and lower hinge region of the human IgG1 molecule. In contrast, it binds only weakly to the same peptide in monomeric form (225-237) or to a short double chain hinge peptide (225-232/225'-232'). The double chain peptides comprise a cyclic region between the two cystine bridges and an exocyclic region. Previous nuclear magnetic resonance analyses showed that the cyclic portion of the short double chain hinge peptide adopts the same conformation as that found in the intact IgG1 molecule. The dichroic properties of the short and long double chain hinge peptides indicate that they have identical conformations in their cyclic regions, but have different conformations in their exocyclic regions. The conformational differences in the exocyclic regions explain the binding of the Ab to the long double chain hinge peptide and the lack of binding to the short one. The circular dichroism spectrum of the monomeric hinge peptide, which is not recognized by the Ab, is consistent with the absence of an ordered peptide structure. These findings lead us to conclude that the IgG anti-F(ab')2 Ab recognizes a conformational IgG1 hinge epitope.

The natural human IgG anti-F(ab')2 antibody recognizes a conformational IgG1 hinge epitope

Natural IgG anti-F(ab')2 Abs are part of the physiologic immune repertoire and have important immunoregulatory functions. Although previous work suggested that some of these Abs recognize epitopes located in the constant region of the F(ab')2 molecule, an exact epitope mapping has not been performed. We found that the anti-F(ab')2 Ab binds strongly to F(ab')2 but only weakly to Fab fragments. Fab fragments are lacking the core and lower hinge region. In our experiments, we show that the IgG anti-F(ab')2 Ab binds strongly to a synthetic double chain peptide (225-237/225'-237') comprising the core and lower hinge region of the human IgG1 molecule. In contrast, it binds only weakly to the same peptide in monomeric form (225-237) or to a short double chain hinge peptide (225-232/225'-232'). The double chain peptides comprise a cyclic region between the two cystine bridges and an exocyclic region. Previous nuclear magnetic resonance analyses showed that the cyclic portion of the short double chain hinge peptide adopts the same conformation as that found in the intact IgG1 molecule. The dichroic properties of the short and long double chain hinge peptides indicate that they have identical conformations in their cyclic regions, but have different conformations in their exocyclic regions. The conformational differences in the exocyclic regions explain the binding of the Ab to the long double chain hinge peptide and the lack of binding to the short one. The circular dichroism spectrum of the monomeric hinge peptide, which is not recognized by the Ab, is consistent with the absence of an ordered peptide structure. These findings lead us to conclude that the IgG anti-F(ab')2 Ab recognizes a conformational IgG1 hinge epitope.

Striking inverse correlation between IgG anti-F(ab')2 and autoantibody production in patients with cold agglutination

Previous experiments showed that the physiologic IgG anti-F(ab')2 antibody suppresses the response of human autoreactive B cells. In the present study, we analyzed the IgG anti-F(ab')2 antibody in 293 patients with cold agglutination (CA). Their average IgG anti-F(ab')2 titer was not much different (211 +/- 8.3) from that of 279 healthy persons (195 +/- 6.7). However, CA patients with high anti-F(ab')2 titers had low CA autoantibody titers and vice versa (P = .0028; rho = -0.175). The stratification of patients according to the auto-antibody's specificity (anti-I, anti-i, anti-Pr) showed an inverse correlation between anti-F(ab')2 and CA in the anti-I group (P = .0057; rho = -0.180). Interestingly, the association was present only in patients whose disease was caused by noninfectious agents (P < .0001; rho = -0.423). The inverse correlation argues for an important role of the IgG anti-F(ab')2 in the regulation of autoantibody production in CA patients.

[Familial epidemics of tick-borne encephalitis in central Povazie]

The authors describe two cases of tick-born encephalitis family epidemies in the natural focus of tick-born encephalitis (TbE) in the central part of Povazie in the district of Povazká Bystrica in the years 1989 and 1993. The infection took place due to consumption of raw goat milk. The best prevention against tick-born encephalitis is represented by vaccination. (Tab. 4, Ref. 6.)

Frequency and transferability of trimethoprim and sulfonamide resistance in methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis

A total of 374 Staphylococcus aureus and 126 Staphylococcus epidermidis strains from 14 countries were studied for their resistance to methicillin, trimethoprim (Tp) and sulfonamides (Su), alone and combined (TpSu). The frequency of resistance to Tp, Su and TpSu was much higher in methicillin-resistant S. epidermidis (MRSE) than in methicillin-resistant S. aureus (MRSA). Considerable differences, however, existed in isolates from different countries. Resistance to Tp, Su or TpSu in MRSA was low or absent in isolates from Switzerland, Spain, Japan, Mexico, Argentina and Chile, but high in isolates from Germany and Brazil. High level Tp resistance mostly resided on large plasmids. It could be transferred in 17 out of 97 strains. Su resistance was never cotransferred. Strains cured of their large Tp resistance plasmids remained Su-resistant, which suggests a chromosomal location of Su resistance.

Coexpression of CD4 and CD8 on mitogen-activated peripheral blood T cells from children with asthma: possible involvement of interleukin 4

Mononuclear cells were isolated from the peripheral blood of 28 asthmatic and 18 healthy children aged 3 to 16 years. The cells were stimulated with phytohemagglutinin for 96 hours. Activated cells were detected microscopically by MTT staining. Expression of cell surface antigens was detected by indirect immune fluorescence using CD4-specific and CD8-specific monoclonal antibodies. Results indicate an enhanced expression of CD8 on mitogen-activated T cells from asthmatic children compared with cells from healthy controls (median 43% versus 27%). Further experiments revealed that CD8 is coexpressed with CD4 on activated lymphocytes. Coexpression is significantly enhanced with lymphocytes from asthmatic patients compared with normal controls. In addition, interleukin 4 is able to enhance this coexpression with lymphocytes from healthy but not asthmatic children suggesting an in vivo preactivation of lymphocytes from asthmatic patients with interleukin 4.

Affinity of carumonam for penicillin-binding proteins

Direct labeling experiments with [14C]-carumonam as well as competition binding assays with [14C]-benzylpenicillin and [14C]-ceftriaxone have demonstrated that penicillin-binding protein (PBP) 3 of Escherichia coli, Enterobacter cloacae and Pseudomonas aeruginosa has the highest affinity for carumonam (Ro 17-2301, AMA-1080). PBP 1a is inhibited only at significantly higher concentration whereas other PBPs display poor affinity. The IC50 values for binding to PBP 3 in E. coli and E. cloacae are in the range of the MIC-values (0.1-0.4 micrograms/ml), whereas those for P. aeruginosa are much lower than the MIC obtained in vitro. In accordance with the PBP affinity pattern observed for carumonam, filament formation resulted after exposure to concentrations greater than 1/2 MIC. Although PBP 1 and 2 of Staphylococcus aureus could be titrated with radioactive carumonam, very high concentrations were required and in line with the poor affinity for all four PBPs in S. aureus, this organism is resistant to carumonam.