Immunological structure of the population vis-à-vis the meningococcus]

The immunological and epidemiological study of 3362 serum samples selectively taken from healthy persons in Yaroslavl showed the presence of highly pronounced inverse correlation between morbidity rate indices and level of antibodies, as well as direct correlation between the level of carriership and the level of antibodies, which indicated the specific character of this process. The analysis of serological data showed that all meningococcal antigenic fractions took part in the formation of the immunological structure of the population, but lipopolysaccharides and polysaccharides played the most active role in this process. The level of all immunoglobulin classes (especially IgA) in the sera of the persons selected for this study was also shown to depend on their age.     

Topographical localization of distinct antigenic domains of Toxoplasma gondii with the aid of monoclonal antibodies

In the present study, a panel of six individual hybridoma derived antibodies produced against the BK strain of Toxoplasma gondii were evaluated for their reactivity in an immunofluorescence test. Each of the six monoclonal antibodies demonstrated a unique pattern of fluorescence localized to distinctive regions on the toxoplasmas. Although all of the six detected antigenic determinants which were shared by at least four different T. gondii strains, monoclonal antibody TG-E4A17 has disclosed hitherto unrecognized population differences among the BK or PH strain parasites. The fact that some of the antigenic molecules are restricted to distinct regions of the toxoplasmas may have implications in the infections process/immune response.     

Evidence for positive selection in the capsid protein-coding region of the foot-and-mouth disease virus (FMDV) subjected to experimental passage regimens

We present sequence data from two genomic regions of foot-and-mouth disease virus (FMDV) subjected to several experimental passage regimens. Maximum-likelihood estimates of the nonsynonymous-to-synonymous rate ratio parameter (d(N)/d(S)) suggested the action of positive selection on some antigenic sites of the FMDV capsid during some experimental passages. These antigenic sites showed an accumulation of convergent amino acid replacements during massive serial cytolytic passages and also in persistent infections of FMDV in cell culture. This accumulation was most significant at the antigenic site A (the G-H loop of capsid VP1), which includes an Arg-Gly-Asp (RGD) cellular recognition motif. Our analyses also identified a subregion of VP3, part of the fivefold axis of FMDV particles, that also appeared to be subjected to positive selection of amino acid replacements. From these results, we can conclude that under the restrictive conditions imposed either by the presence of the monoclonal antibodies, by the persistent infections, or by the competition processes established between different variants of the viral population, amino acid replacement in some capsid-coding regions can be positively selected toward an increase of those mutants with a higher capability to infect the cell.     

Comparative study of the smallpox vaccines from B-51, EM-63 and L-IVP in a controlled epidemiological experiment. II. The characteristiics of the immunogenicity of the smallpox vaccines]

Immunogenicity of smallpox vaccines prepared of EM-63, L-IVP, and B-51 strains was studied under conditions of strict controlled epidemiological trial. Skin reactions to revaccination and vaccines antigenic activity indices were detemined in the persons vaccinated. Changes in the virus-neutralizing and antibodies suppressing hemagglutination was the same in persons vaccinated with any of the preparations tested. The maximal virus-neutralizing antibodies level was determined 1 month after the vaccination and persisted without any essential changes for one year. The titre of hemagglutination inhibiting antibodies also reached the maximum in one month, but diminished gradually by the end of one year after the vaccination. There were found no significant differences in the antigenic activity of the vaccines. The vaccines studied also displayed no difference in the number and character of skin reactions to revaccination. In comparing the antibodies level and the character of skin reactions to revaccination it was found that the titres of hemagglutination inhibiting antibodies and virus-neutralizing antibodies of 1:40 and over were in the great majority of cases determined in the blood sera of the vaccinated persons with the immediate and negative reactions to revaccination, i. e. in those with intensive postvaccinal immunity.     

Influence of age and sex on levels of anti-oxidized LDL antibodies and anti-LDL immune complexes in the general population

Most studies of antibodies to oxidized LDL have been undertaken in patients with different diseases and cardiovascular risk factors. However, very few studies have researched the distribution and determining factors of antibodies to oxidized LDL in the general population. A total of 1,354 persons (817 females and 537 males) aged 5-65 years were included in this study. They were selected randomly from the population census of Málaga, in southern Spain. The females had lower levels of total cholesterol and triglycerides and higher levels of HDL-cholesterol and a very significant increase (P < 0.0001) in levels of anti-oxidized LDL [low density lipoprotein modified by malondialdehyde (MDA-LDL)] antibodies but no difference in levels of immune complexes consisting of LDL and IgG antibodies (anti-LDL immune complex). Younger persons (16-35 years) had higher levels of anti-oxidized LDL (MDA-LDL) antibodies than persons older than 35 years (P = 0.05). Levels of immune complexes were significantly higher (P = 0.05) in persons aged 5-15 years than in persons older than 40 years. A very weak association was found between levels of anti-oxidized LDL (MDA-LDL) antibodies and anti-LDL immune complexes. The higher prevalence of anti-oxidized LDL (MDA-LDL) antibodies in females and young persons is in agreement with studies that found an inverse association between atherosclerosis and the level of these antibodies.     

Antigenic variation and the murine immune response to Giardia lamblia

The protozoan parasite Giardia lamblia is an important causative agent of acute or chronic diarrhoea in humans and various animals. During infection, the parasite survives the hosts reactions by undergoing continuous antigenic variation of its major surface antigen, named VSP (variant surface protein). The VSPs form a unique family of cysteine-rich proteins that are extremely heterogeneous in size. The relevance of antigenic variation for the survival in the host has been most successfully studied by performing experimental infections in a combined mother/offspring mouse system and by using the G. lamblia clone GS/M-83-H7 (human isolate) as model parasite. In-vivo antigenic variation of G. lamblia clone GS/M-83-H7 is characterised by a diversification of the intestinal parasite population into a complex mixture of different variant antigen types. It could be shown that maternally transferred lactogenic anti-VSP IgA antibodies exhibit cytotoxic activity on the Giardia variant-specific trophozoites in suckling mice, and thus express a modulatory function on the proliferative parasite population characteristics. Complementarily, in-vitro as well as in-vivo experiments in adult animals indicated that non-immunological factors such as intestinal proteases may interfere into the process of antigen variation in that they favour proliferation of those variant antigen-type populations which resist the hostile physiological conditions within the intestine. These observations suggest that an interplay between immunological and physiological factors, rather than one of these two factor alone, modulates antigenic diversification of a G. lamblia population within an experimental murine host and thus influences the survival rate and strategy of the parasite.     

Monoclonal antibody analyses of cytopathic and noncytopathic viruses from fatal bovine viral diarrhea virus infections.

A panel of monoclonal antibodies that recognize the two major glycoproteins of bovine viral diarrhea virus (BDV) was used to evaluate the antigenic relationship between cytopathic (CP) and noncytopathic (NCP) viruses isolated from cattle dead or dying from fatal BDV infections. Various unrelated BDV isolates were initially screened by indirect immunofluorescence with monoclonal antibodies directed against the 56- to 58- and 48-kilodalton glycoproteins of the virus. A wide spectrum of reactivity that was independent of biotype was found. Biological clones of the same isolate showed only minor variations from the parental isolate, as did isolates taken from different animals located on the same farm. A similar analysis was repeated with pairs of CP and NCP viruses isolated from 16 unrelated clinical cases of BDV infection resulting in fatal disease. The reactivity patterns within individual pairs of isolates taken from the same animals were in most instances very similar and in some cases indistinguishable from one another. The results demonstrate that antigenic similarity between biotypes is a consistent finding in animals dying from fatal BDV infections. In view of the wide degree between biotypes is a consistent finding in animals dying from fatal BDV infections. In view of the wide degree of variation in reactivity patterns between unrelated BDV isolates, the close antigenic similarity of CP BDV to the homologous NCP BDV of a given pair strongly suggests that CP BDV arises by mutation from NCP BDV.     

Paramyxovirus membrane protein enhances antibody production to new antigenic determinants in the actin molecule: a model for virus-induced autoimmunity.

Paramyxovirus membrane (M) protein specifically binds to cellular actin but not to bovine serum albumin or myoglobin, as determined by affinity chromatography and enzyme-linked immunosorbent assay. The binding site for M protein on actin is different from the binding sites for antiactin antibodies. The interaction of M protein with actin resulted in production of antibodies to several new antigenic sites on the actin molecule. Five rabbits immunized with actin alone produced antibodies against the N-terminal sequence (residues 1 to 39). Another five rabbits immunized with a mixture of M protein and actin produced antibodies against a C-terminal fragment and a central region as well as the N-terminal fragment. By immunoblotting with proteolytic fragments of actin, the new antigenic sites were located between amino acid residues 40 to 113, 114 to 226, and 227 to 375. Antisera taken from some patients with recent measles virus infections demonstrated antiactin antibodies to sites other than the N-terminal fragment of actin (amino acids 1 to 39). The interaction of paramyxovirus M protein with actin and the subsequent production of antibodies to new antigenic sites may serve as a model for one of the mechanisms of virus-induced autoimmunity.     

Competitive inhibition by human sera of mouse monoclonal antibody binding to glycoproteins C and D of herpes simplex virus types 1 and 2.

A competitive enzyme-linked immunosorbent assay was used to test for human antibodies to antigenic sites on herpes simplex virus (HSV) glycoproteins C and D, which are recognized by mouse monoclonal antibodies. Antibodies capable of blocking the monoclonal antibodies were detected in the human sera, and the inhibition of binding correlated with the histories of herpetic infections. The binding of monoclonal antibody to glycoprotein C of HSV type 2 was inhibited primarily by sera from patients with recurrent herpes genitalis; however, the binding of the monoclonal antibodies to gC of HSV type 1 was inhibited by sera from patients previously infected with either HSV type 1 or HSV type 2. The observations suggest that the antigenic sites defined by the mouse monoclonal antibodies are recognized by the human host.     

Regional epidemiologic characteristics of combined foci of tick-borne encephalitis, endemic rickettsioses and leptospirosis in Western Siberia

The authors carried out complex study of combined foci of infections with natural foci in Western Siberia and their reflection in human pathology. The results of serological examination of 5917 persons and of 1743 of farm animals in respect to tick-borne encephalitis, Asian tick-borne rickettsiosis, Q-rickettsiosis, and leptospiroses are analysed. Affection of the population with all the four infections in all the landscape zones under study was shown; the intensity of this affection with different infections differed. Combined natural foci of the mentioned infections were found to be widespread; epidemiological significance of such combination was unequal in different ladscapes, this depending on the ladscape characteristics of the natural foci of infections under study and of different ways of transmission of their causative agents.     

The reactogenicity and antigenic activity of a meningococcal group B vaccine made from a natural complex of the specific polysaccharide and outer membrane proteins

Group B meningococcal vaccine consisting of the natural complex of specific polysaccharide and outer membrane protein (OMP) has been shown to be moderately reactogenic, safe with respect to the effect of undermining tolerance to human brain tissue antigens and to produce no allergization of humans. The vaccine under study possesses antigenic activity: (a) immunization with this vaccine ensures the fourfold rise of the level of antibodies to the group-specific polysaccharide of group B meningococcus in about 80% of persons with the initially low level of antibodies, this percentage being retained during the whole period of observation, i. e. 85 days; (b) the vaccine enhances the level of antibodies to meningococcal OMP, determined in the enzyme immunoassay and the passive hemagglutination test; (c) these data are indicative of the expediency of immunizing the risk groups of persons with the initially low level of antibodies.     

Immunological study of cytomegalovirus complement-fixing antibodies in the population of the CSR.

The population from different regions of the CSR was examined serologically for the presence of cytomegalovirus (CMV) antibodies. Exclusively persons showing no signs of disease, chosen by random selection, were examined. The immunological survey was carried out by the complement fixation reaction with CMV antigen prepared in the laboratory from the international strain AD 169. The high incidence found in normal population is suggestive of a considerable dispersion of cytomegalovirus infection. The contact with the virus is followed by antibody response, manifested in most cases only subclinically and asymptomatically. The incidence of CMV antibodies increases with increasing age. In young age groups, antibodies were found in approximately 20%. The number of persons showing positive reactions increased gradually and in the oldest age groups antibodies were found in 70%. The significance of factors causing the incidence of cytomegalovirus antibodies in the population is discussed.     

Immune structure of the population in some regions of the USSR with respect to Legionella pneumophila

For the first time in the USSR the structure of the immunity of different population groups to L. pneumophila was studied. Antibodies to L. pneumophila were detected in the passive hemagglutination test with the use of erythrocyte diagnosticum prepared at the Gamaleya Research Institute of Epidemiology and Microbiology (Moscow). The survey covered the total number of 2,902 persons in differ nt regions of the USSR, among them 2,430 adults and 472 children. Among the healthy adult population antibodies to L. pneumophila were detected, on the average, in 5.9% of persons. The highest number of persons with antibodies in diagnostic titers was detected among the population of the Baltic Republics (15.9%) and Kazakhstan (10.2%). The survey revealed an essential difference in the number of children aged 3-7 years, found to have antibodies to L. pneumophila, in the Brest region of the Byelorussian SSR (31.4%) and in the Turkmen SSR (1.3%). The high risk groups exposed to L. pneumophila infection were found to include narcological patients with the changed reactivity of the body and healthy adults professionally employed in earth-moving works.     

Occurrence of infections with C burnetii (Q fever) in persons from increased risk groups in Poland--serological survey and evaluation of studied methods]

During years 1988-1991 at Regional Sanitary and Epidemiological Stations in Bia?ystok, Kielce, Lublin, Leszno, Piotrków Trybunalski, Lód?, Poznań, Plock, Opole, Sanok, Skierniewice and Zielona Góra--serological studies in persons amenable to compulsory check-up against brucellosis were performed for detection of infections with C. burnetii. In whole, 20651 persons were investigated on the Polish territory and it was found that in 22.8% antibodies against antigens of C. burnetii are present. Percentage of persons with detected antibodies varied in different regions from 0 to 41.7%. No antibodies were found in persons inhabiting regions of Kielce, Piotrków Trybunalski and Skierniewice. Most persons with antibodies indicating contact with C. burnetii were found in West Poland, namely in the Leszno and Poznań region. As in diagnosis of Q fever two methods (OWD and OMA) or OWD only were applied, it is difficult to compare results obtained in regions using two or only one method of determination.     

Antigenic determinants of the HLA-B7 molecule; Bw6- and B7-specific determinants are spatially separate

Monoclonal antibodies that bind HLA-B7 were used to show that the B7-specific determinant is at a topologically different site from that of the broad polymorphic, Bw6 determinant. The relationship to other antigenic determinants defined by monoclonal antibodies was also assessed. These results were independently obtained in four ways: (1) by cellular blocking assays, in which there was no inhibition of 125I-B7 antibody binding in the presence of Bw6 antibody and no inhibition of 125I-Bw6 antibody binding in the presence of B7 antibody; (2) cellular binding assays under conditions of antibody saturation showed the binding of B7-specific and Bw6 antibodies were additive; (3) solid-phase radioimmune assays demonstrated enhancement between B7-specific and Bw6 antibodies; (4) analysis of antigen antibody complexes by size-exclusion high pressure liquid chromatography showed Bw6 and B7 antibodies could form tetramolecular complexes with papain-solubilized HLA-B7. Limitations were encountered in using cellular blocking assays to map antigenic determinants of HLA-B7. These assays can produce blocking in cases where two antibodies are not competing for an antigenic determinant. Mapping antigenic determinants with assays using purified HLA-B7 as the antigenic target, in addition to cell-based assays, provided a more accurate picture.     

Antigenic population changes of Leptospira biflexa strains grown under the selective pressure of factorial antibodies

Serovars jequitaia and tororò of Leptospira biflexa were cultured in the presence of homologous factor serum containing factorial antibodies (FcAbs) to their major antigens. After 39 serial passages they were then re-tested to determine whether their major antigens had remained unchanged. It was found that each parent strain had been replaced by an antigenic variant. The disappearance of each parent strain and its replacement by an antigenic variant was attributed to the selective conditions imposed by FcAbs. The antigenic variants behaved like true mutants. They lacked the major serovar antigens of the parent strains and had acquired some major antigens similar to those of two different serovars, one of which belonged to the same serogroup as the parent strain and the other to a different serogroup. A comparison of the major antigens of the parent strains with those of their antigenic variants indicated that factorial antibodies may be used selectively to obtain antigenic variants with a predefined pattern of major antigens.     

Diseases and reproductive success in a wild mammal: example in the alpine chamois

Density-dependent and climatic factors affect reproduction and dynamics of wild ungulates. Parasites can also decrease reproductive success through either a direct abortive effect or a negative impact on host growth and body condition. However, few studies have investigated the effect of parasitism on fecundity of ungulates in natural conditions. We studied three bacterial infections caused by Salmonella enterica serovar Abortusovis, Chlamydophila abortus and Coxiella burnetii. These bacteria are leading causes of reproductive failure in sheep, goat and cattle, which raises the question of their influence on population dynamics of wild ungulates. A long-term study of demography and epidemiology of an alpine chamois (Rupicapra rupicapra, L.) population (Les Bauges Reserve, France) and a generalized linear modeling approach were used to analyze the reproductive success of chamois according to population density, weather conditions and the prevalence of antibodies against the three bacteria in females. This approach enabled us to identify the confounding effect of weather and parasitism on fecundity in a natural population. After accounting for density, the prevalence of antibodies against the three bacteria explained 36% of the annual variation in reproductive success, and weather conditions explained an additional 31%. This study was, to our knowledge, the first to compare the decrease in fecundity due to bacterial infections and weather conditions in a population of wild mountain ungulates.     

Infinite Serovar and Ribotype Heterogeneity Among Oral Fusobacterium nucleatum Strains?

Fusobacterium nucleatum is part of the residential human microbiota and is associated with various infections. It is characterised by broad genetic heterogeneity, but reliable phenotypic markers are lacking. The purpose of the present study was to generate antibodies for the detection of F. nucleatum , to characterise expression patterns of the detected surface antigens on oral isolates, to investigate the prevalence of distinguishable subtypes in clinical samples from the oral cavity, and to compare antigenic with ribotype heterogeneity. Thirty-seven monoclonal antibodies (mAbs) were generated and characterised using strains from 52 taxa. Antibody-binding bacteria were monitored in 35 samples of supra- and subgingival plaque from healthy sites and sites affected by gingivitis or periodontitis. Results indicated broad but structured antigenic heterogeneity. Detecting at least 28 different epitopes, the mAbs defined 19 serovars. Epitopes were expressed on periodate-sensitive polysaccharide chains. Ribotyping of 40 oral F. nucleatum strains (Pvu II digestion) resulted in the detection of similarly broad genetic heterogeneity, which rarely corresponded to the observed phenotypic diversity. Clinical samples were generally positive for multiple (up to eight) serovars of which some colonised supra- and subgingival plaques from both healthy and diseased sites, whereas others were restricted to inflamed sites. The majority of the studied isolates could not be grouped with reference strains of the five established subspecies of F. nucleatum , corroborating doubts about the usefulness of the current classification scheme. Although, as a whole the described monoclonal antibodies can only recognise a part of the overwhelming heterogeneity of this ‘species’, they should prove of value to investigations of the importance, the antigenic stability and the origin of positive subtypes of F. nucleatum from human infections     

Geographic distribution of humans,raccoons, and white-footed mice with antibodies to Lyme disease spirochetes in Connecticut.

An indirect immunofluorescence test was used during 1982-1983 to identify antibodies to Lyme disease spirochetes in humans, white-footed mice, and raccoons. Serologic tests detected IgM or total Ig antibodies in serum samples from 67 persons. Onset of illness, as marked by erythema chronicum migrans (ECM), occurred mainly during July and August. The majority of the persons with Lyme disease lived in south central and southeastern Connecticut. Analyses also verified prior spirochetal infections in 29 of 323 (9 percent) white-footed mice and in three of 34 (9 percent) raccoons captured at sites with or without evidence of human infections. Results indicate potential for Lyme disease at numerous localities in Connecticut.     

The use of the microdot immunoenzyme method for determining antibodies to Mycobacterium tuberculosis antigens

The microdot enzyme immunoassay (EIA) has been used for the determination of antibodies to M. tuberculosis protein fractions, crude antigenic preparations, PPD and old tuberculin in tuberculosis patients and healthy persons. Purified protein fractions have been found to possess the highest sensitivity and specificity in microdot EIA. The determination of antibodies to these fractions has permitted the differentiation of persons infected with M. tuberculosis from healthy ones. The use of M. tuberculosis protein fractions permits the determination of IgA and IgC in the sera of tuberculosis patients.