STUDIES ON THE PRECIPITIN REACTION : PRECIPITATING HAPTENS; SPECIES DIFFERENCES IN ANTIBODIES

Detection of West Nile Virus Envelope Protein in Brain Tissue with an Immunohistochemical Assay

Immunohistochemistry is a valuable tool for probing not only scientific questions but also clinical diagnoses. It provides power from localization of a protein within the milieu of a tissue section that may reflect positioning within or beyond the boundaries of a cell that is representative of the tissue at a discrete moment in time. The method can be applied broadly, including to tissues under normal, developmental, chemically, or genetically altered conditions and disease states.Disease manifesting from West Nile virus infection ranges from acute, systemic febrile symptoms to compromise of central nervous system function. Immunohistochemistry has been used to assess WNV infection in the nervous system in postmortem and experimental conditions, despite the lack of understanding of the precise route of viral entry. In addition to imprecise knowledge of initial viral entry into cells and whether entry is even the same between cell types, the fact that spontaneous viral mutations and environmental pressures from climate change may alter the prevalence of the disease state across geographical and climatological boundaries highlights the need for continued assessment of infection. Immunohistochemistry is a useful way to assess these aspects of WNV infection with the aim being to better understand the organs and cell types that are compromised by WNV infection. This chapter outlines how this can be carried out on brain tissue, but the procedures discussed can also be applied more broadly on tissue outside of the central nervous system.

Discovery of Semi- and Fully-Synthetic Carbohydrate Vaccines Against Bacterial Infections Using a Medicinal Chemistry Approach

The glycocalyx, a thick layer of carbohydrates, surrounds the cell wall of most bacterial and parasitic pathogens. Recognition of these unique glycans by the human immune system results in destruction of the invaders. To elicit a protective immune response, polysaccharides either isolated from the bacterial cell surface or conjugated with a carrier protein, for T-cell help, are administered. Conjugate vaccines based on isolated carbohydrates currently protect millions of people against Streptococcus pneumoniae, Haemophilus influenzae type b, and Neisseria meningitides infections. Active pharmaceutical ingredients (APIs) are increasingly discovered by medicinal chemistry and synthetic in origin, rather than isolated from natural sources. Converting vaccines from biologicals to pharmaceuticals requires a fundamental understanding of how the human immune system recognizes carbohydrates and could now be realized. To illustrate the chemistry-based approach to vaccine discovery, I summarize efforts focusing on synthetic glycan-based medicinal chemistry to understand the mammalian antiglycan immune response and define glycan epitopes for novel synthetic glycoconjugate vaccines against Streptococcus pneumoniae, Clostridium difficile, Klebsiella pneumoniae, and other bacteria. The chemical tools described here help us gain fundamental insights into how the human system recognizes carbohydrates and drive the discovery of carbohydrate vaccines.

THE PRECIPITIN REACTION BETWEEN TYPE III PNEUMOCOCCUS POLYSACCHARIDE AND HOMOLOGOUS ANTIBODY : III. A QUANTITATIVE STUDY AND A THEORY OF THE REACTION MECHANISM

The precipitin reaction between the specific polysaccharide of Type III pneumococcus and homologous antibody formed in the horse can be accounted for quantitatively by assuming the chemical combination of the components in a bimolecular reaction, followed by a series of competing bimolecular reactions which depend upon the relative proportions of the components. These reactions would lead to the formation of larger and larger aggregates until precipitation ultimately occurred. The mathematical formulation of this theory on the basis of the mass law is described. The derived expressions are shown to be in accord with the experimental findings and the constants used in these expressions are shown to have definite significance. In spite of the wide variation in the properties of individual sera these expressions permit the complete description of the behavior of an unknown serum with S III without an unduly burdensome number of analyses. The quantitative theory presented has been found applicable to other instances of the precipitin reaction, as will be shown in subsequent papers.

IMMUNOLOGICAL STUDIES ON A NEW PREPARATION OF TYPE SPECIFIC POLYSACCHARIDE FROM PNEUMOCOCCUS TYPE I

A type specific polysaccharide has been isolated from the autolyzed broth of Type I Pneumococcus by a modified Avery and Goebel's method. The newly prepared polysaccharide reacts with the homologous immune rabbit serum which has been completely absorbed with the acetyl polysaccharide of Avery and Goebel. The newly prepared polysaccharide produces passive immunity in mice and rats and possibly in rabbits. The antigenicity is not lost on boiling in acid or alkaline medium, but the precipitative activity is decreased. In conclusion, it has been shown that the polysaccharide from Type I Pneumococcus, as isolated by a slight modification of Avery and Goebel's method, is a more complete antigen.

STUDIES ON MENINGOCOCCUS INFECTION : IX. STANDARDIZATION AND CONCENTRATION OF ANTIMENINGOCOCCUS HORSE SERUM (TYPE I)

Type I antimeningococcal horse sera have been standardized by the quantitative determination of their type-specific precipitin content. By a method involving dialysis and precipitation by treatment with carbon dioxide, the antibody in such sera has been purified tenfold with respect to the nitrogen content.

THE SPECIFIC POLYSACCHARIDES OF TYPES I, II, AND III PNEUMOCOCCUS : A REVISION OF METHODS AND DATA

1. The thermolability of the specific polysaccharides of Types I, II, and III pneumococcus has been shown by three independent methods: (a) diminution of the viscosity of solutions on heating; (b) decrease in the amount of antibody precipitated from homologous rabbit antisera; and (c) increased tendency (S III) to pass through a collodion membrane. 2. These effects may be explained most simply as a partial depolymerization under the influence of heat. In air, particularly in the presence of broth, oxidation also appears to be involved. 3. Improved and simpler methods of preparation based on these findings, are given for S I, S II, and S III. The resulting products precipitate more anti-S from homologous rabbit antisera than do the earlier preparations. 4. The methyl glycoside of methyl galacturonate has been isolated from the hydrolytic products of S I, and evidence of the ultimate structural unit obtained.

THE MOLECULAR WEIGHT OF ANTIBODIES

1. Highly purified rabbit Type III pneumococcus anticarbohydrate proved to be homogeneous in the ultracentrifuge and its sedimentation constant, 7.0·10^–13, did not differ from that of the principal component of normal rabbit globulin or of immune rabbit globulin containing up to 50 per cent of anti-egg albumin. The molecular weight of antibody in the rabbit is therefore probably very close to that of the principal normal globulin component, namely, 150,000. 2. Highly purified horse Type I pneumococcus anticarbohydrate, on the other hand, was only homogeneous in the ultracentrifuge when prepared from sera stored without preservative. Its sedimentation constant, 18.4·10^–13, coincided with that of the principal globulin component in most of the Felton solutions and purified antibody solutions studied. The molecular weight of pneumococcus anticarbohydrate in the horse is probably three to four times that of the principal normal globulin component. 3. The significance of the differences between pneumococcus anticarbohydrate formed in the rabbit and in the horse is discussed. 4. Results are given of ultracentrifuge studies on the molecular species in solutions of egg albumin-anti-egg albumin specific precipitates dissolved in excess egg albumin. The implications of the results are discussed.

THE IMMUNOLOGICAL RELATIONSHIP OF THE CAPSULAR POLYSACCHARIDE OF TYPE XIV PNEUMOCOCCUS TO THE BLOOD GROUP A SPECIFIC SUBSTANCE

1. The agglutination of human erythrocytes and the precipitation of the blood group A substance by Type XIV antipneumococcus horse serum are properties of the specific anticarbohydrate immune bodies in the serum. 2. Absorption of Type XIV antipneumococcus horse serum with the homologous bacterial polysaccharide removes the agglutinins for human erythrocytes as well as the precipitins for the group A substance. 3. Absorption of Type XIV antipneumococcus horse serum with the group A substance markedly diminishes the ability of the serum to agglutinate erythrocytes of all groups. 4. Absorption of Type XIV antipneumococcus horse serum with human erythrocytes causes a marked diminution in the precipitation with group A substance. 5. The chemical and immunological relationship between the specific substances of blood group A and the Type XIV Pneumococcus is discussed.

A QUANTITATIVE THEORY OF THE PRECIPITIN REACTION : IV. THE REACTION OF PNEUMOCOCCUS SPECIFIC POLYSACCHARIDES WITH HOMOLOGOUS RABBIT ANTISERA

1. The reaction between the specific polysaccharide of Type III pneumococcus and homologous antibody in rabbit sera is quantitatively accounted for by expressions similar to those derived from the mass law for the corresponding horse sera. Preliminary data are also given for the Type I reaction. 2. Differences and similarities of the reaction with antibodies produced by the two animals are discussed. 3. Calculations are made of the equivalent composition of the specific precipitate at various reference points in the reaction range. 4. Certain theoretical and practical implications of the findings are pointed out.

CHEMO-IMMUNOLOGICAL STUDIES ON CONJUGATED CARBOHYDRATE-PROTEINS : XII. THE IMMUNOLOGICAL PROPERTIES OF AN ARTIFICIAL ANTIGEN CONTAINING CELLOBIURONIC ACID

1. Artificial antigens containing the azobenzyl glycosides of the disaccharide cellobiose and the aldobionic acid, cellobiuronic acid, give rise in rabbits to antibodies which are specific and characteristic of the saccharide constituent. The antiserum to cellobiuronic acid shows broader serological cross reactions than does that to cellobiose. 2. An antiserum to the cellobiuronic acid antigen precipitates the capsular polysaccharide of Type III Pneumococcus when the latter is combined with a heterologous protein. 3. The cellobiuronic acid test antigen precipitates vigorously in antipneumococcus sera Types II, III, and VIII. The mechanism of these reactions is discussed.

QUANTITATIVE STUDIES ON ANTIBODY PURIFICATION : II. THE DISSOCIATION OF ANTIBODY FROM PNEUMOCOCCUS SPECIFIC PRECIPITATES AND SPECIFICALLY AGGLUTINATED PNEUMOCOCCI

1. The salt dissociation and barium hydroxide-barium chloride methods are extended to the preparation of highly purified antibody solutions from specific precipitates derived from Type III and Type VIII antipneumococcus horse sera and a low grade polyvalent bovine serum. Analytically pure precipitin (agglutinin) was obtained from the last, and Types I, II, and III antibodies were separated. 2. Difficulties connected with the application of the methods to Type I antipneumococcus rabbit sera are described, as is also the purification of antibody from low grade pig and sheep sera. 3. The dissociation of antibody by both methods from Type I pneumococci agglutinated in antisera produced in the horse, rabbit, pig, and sheep, is described and its advantages discussed. 4. Certain theoretical aspects of the work are also discussed.

THE MOLECULAR WEIGHT OF ANTIBODIES

1. Highly purified preparations of homogeneous antibody can be made by the salt dissociation methods (6, 7) without any change in sedimentation due to the method of purification. 2. Antibodies prepared from sera of various animal species fall into two groups as regards molecular weight; in one group cow, horse, and pig, a heavy molecule of molecular weight 990,000 is formed; in human being, rabbit, and monkey, the molecular size is that of the normal gamma serum globulin. Both types of antibody molecules are either not compact or not spherical since the frictional ratios f/f(0) are 2.0 and 1.5 respectively. 3. Horse antibody shows an unchanged activity and sedimentation diagram between pH 3.44-9.06, although there is some aggregation at the more acid and some dissociation at the more alkaline pH. At pH 1.44 the antibody activity is unchanged but some breakdown of the molecule takes place. At pH 12.4 activity is destroyed and the molecule is completely broken down. 4. Some horse antibody preparations show evidence of breakdown of the antibody into inhomogeneous material on continued immunization over a long period.

QUANTITATIVE EXPERIMENTS WITH ANTIBODIES TO A SPECIFIC PRECIPITATE : III. ANTIGENIC PROPERTIES OF HORSE SERUM FRACTIONS ISOLATED BY ELECTROPHORESIS AND BY ULTRACENTRIFUGATION

1. Rabbit antisera to a Type II pneumococcus specific precipitate from horse serum were tested with fractions prepared by ultracentrifugation and electrophoresis of normal and immune horse serum. 2. In one instance a rapidly sedimenting protein from normal horse serum had nearly the same quantitative antigenic properties toward the anti-antibody rabbit serum as did the purified pneumococcus antibody solutions previously reported. In another instance a comparable fraction removed only a part of the rabbit antibody. 3. Electrophoretic γ-globulin from an immune horse serum had quantitatively the same antigenic properties as did antibody solutions prepared by salt-dissociation of specific precipitates. 4. Electrophoretic γ-globulin from normal horse serum differed in its antigenic behavior from γ-globulin containing antibody. The data are compared with the antigenic properties of acid and alkali treated pneumococcus specific polysaccharides toward antipneumococcus horse sera. An interpretation in terms of polymers is suggested. 5. The cross-reaction of goat serum γ-globulin against the anti-antibody serum is reported and the extent of the reaction compared with those of goat and horse serum albumins against a rabbit antiserum to the latter.

A FURTHER STUDY OF THE CROSS REACTION BETWEEN THE SPECIFIC POLYSACCHARIDES OF TYPES III AND VIII PNEUMOCOCCI IN HORSE ANTISERA

1. The cross reaction of the specific polysaccharide of Type VIII pneumococcus with Type III antipneumococcus horse serum has been studied quantitatively and found similar to the S III-anti-S VIII reaction. 2. Contrasted with the general similarity of the two-segment reaction curves were distinct qualitative and quantitative differences in the course and character of the reciprocal reactions with respect to each segment. 3. These differences could be interpreted in terms of the known chemical differences between the specific polysaccharides of the two types. A minimum molecular weight of 62,000 was calculated for S III and 140,000 for S VIII. 4. It was also found possible to fractionate the Type VIII antibody into portions characteristic of each segment of the cross reaction curve. At least three different kinds of Type III and Type VIII anticarbohydrates were identified.

ON SPECIFIC INHIBITION OF BACTERIOPHAGE ACTION BY BACTERIAL EXTRACTS

1. Experiments are presented demonstrating specific inhibition of phage by soluble products of bacteria. 2. The inhibition proceeds more rapidly when the phage and bacterial extracts are incubated at 37° than at ice box temperature. 3. The specificity of the reaction in the instances studied is probably connected with the presence of specific soluble carbohydrates. 4. A reaction is available for the study of the chemistry of bacillary antigens in terms of bacteriophage.

Isolation of oligosaccharides from a partial-acid hydrolysate of pneumococcal type 3 polysaccharide for use in conjugate vaccines

A series of well-defined oligosaccharide fragments of the capsular polysaccharide of Streptococcus pneumoniae type 3 has been generated. Partial-acid hydrolysis of the capsular polysaccharide, followed by fractionation of the oligosaccharide mixture by Sepharose Q ion-exchange chromatography yielded fragments containing one to seven [-->3)-beta-D-GlcpA-(1-->4)-beta-D-Glcp-(1-->] repeating units. The isolated fragments were analysed for purity by high-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) using an IonPac AS11 column, and their structures were verified by 1H NMR spectroscopy and nano-electrospray mass spectrometry. The oligosaccharides can be used to produce neoglycoprotein vaccines with a defined carbohydrate part.