2 – Antigenic Characteristics and Classification of Togaviridae

Publisher Summary Immunological blockade (IB) may be defined as the inhibition or delay by antibodies of an immune response to specific antigens. This chapter discusses the components and putative mechanisms of IB, which is a synonym of immunological enhancement. IB is depicted as a balanced interaction among antibody, antigen, and responding host. Antibodies that mediate IB belong to the 7 γG class. The host provides an integral ingredient to the process of IB, the nature of which is obscure. To extend the viability of skin homografts in adults that differ at the major histocompatibility locus for more than a few days beyond a normal survival period of 7 to 10 days has been difficult and often unattainable. In neonatal rats, however, survival of skin homografts may continue for weeks in a fraction of grafted recipients; the younger the recipient neonates the more prolonged the viability. Also, in adults that have been irradiated with sublethal doses of X-rays have been thymectomized or have been manipulated with immunosuppressive reagents; skin graft survival may be prolonged days and weeks beyond the usual time of rejection. These observations imply that the immunological apparatus of the recipient must be poorly developed, deficient, or interfered with so that homografts, with the aid of blocking antibodies, may survive for lengthy periods.

Immunological enhancement: a study of blocking antibodies.

Viral and Rickettsial Infections of Man

Publisher Summary The successful demonstration of specific antigens in animal tumors essentially provided a major impetus to the search for comparable antigens in human neoplasms. This chapter examines the considerable amount of data that have accumulated in recent years on tumor-associated antigens (TAAs) of human solid tumors to assess their specificity and their possible usefulness for the early diagnosis of cancer. The selection of material included is arbitrary, as there is an absence of a clear-cut and universally accepted definition for TAA. TAAs are an extremely heterogeneous group of molecules and their overlap with normal antigens is so great that it is practically impossible to define TAAs in such a way so as to distinguish them clearly from ordinary cellular components. The chapter considers a molecule as a TAA if its presence renders the cancer cell quantitatively or qualitatively different from its normal counterpart. TAAs appear to be oncofetal or digerentiation antigens and their apparent specificity is due to their generally increased concentration in the tumor cells.

Human Cancer-Associated Antigens: Present Status and Implications for Immunodiagnosis

Selected yeasts classified as Candida sake van Uden et Buckley were examined for their physiological, morphological and immunological properties and their DNA relatedness. Candida maltosa Komagata, Nakase et Katsuya is herein recognized as a species separate from C. sake. Candida maltosa was distinguished from C. sake and from C. tropicalis by insignificant DNA reassociation. In addition, C. maltosa was distinguished from C. sake by its higher maximal growth temperature and lower guanine plus cytosine content of its DNA and from C. tropicalis by its failure to utilize soluble starch for growth and its resistance to cycloheximide. The species C. cloacae and C. subtropicalis are placed in synonymy with C. maltosa.

Physiological and DNA characterization of Candida maltosa, a hydrocarbon-utilizing yeast.

Hyperimmune New Zealand White rabbit sera prepared against partially purified tumor-associated antigens (TAA) of invasive cervical cancer tissues (CaCx's) were used to demonstrate TAA in CaCx's and circulating TAA (C-TAA) in sera from patients with cervical cancer or with head and neck cancer. Anti-CaCx serum adsorbed with pooled normal cervical tissue (NCx) antigen preparations and with lyophilized pooled normal human plasma gave precipitin in gel reactions with CaCx but not with NCx, which indicated the presence of TAA in CaCx. The adsorbed antisera reacted with sera from patients with cervical and head and neck cancers, which indicated the presence of C-TAA in such sera. False-positive reactions with control sera from normal humans or from patients with benign gynecologic diseases were much less frequently observed. Statistical analysis of data obtained by the testing of 96 coded serum samples from the National Cancer Institute-Mayo Clinic Serum Bank (Rochester, Minn.) revealed that the results were significant and that specificity was high but sensitivity of the assay was relatively low.

Tumor-associated antigens in cervical cancer tissues and in sera from patients with cervical cancer or with head and neck cancer

SummaryUsing the immunodiffusion-adsorption-in-gel and/or the passive hemagglutination techniques, an antigenic relationship has been found between Herpes simplex virus type 2 (HSV-2), cervical cancer tissue antigen preparations, a cell culture derived from cervical cancer, and two HSV-2 associated hamster sarcomas. No cross-reactive antigens were detected between HSV-1, and the HSV-2 related hamster sarcomas or with human cervical cancer.

Common Antigens of Herpes Simplex Virus 2, Associated Hamster Tumors, and Human Cervical Cancer

Summary Six prototypes of dengue viruses, West Nile and Sindbis viruses were cross-reacted in a rather standard type of immunoelectrophoresis test against four rabbit anti-dengue sera representing two closely related pairs as determined by more conventional serology. By this test D-1 and TH-Sman were readily differentiated, each possessing three or four antigens not possessed by the other. One antigen was common to both and to all other dengue protoypes and West Nile virus. A similar differentiation was demonstrated between D-2 and TH-36 and all other viruses employed. One D-2 antiserum demonstrated what may be a subgroup specific dengue antigen shared by all dengues but not by West Nile. The method gives promise of improved differentiation of arboviruses within an antigenic group.

Application of Immunodiffusion Methods to the Antigenic Analysis of Dengue Viruses II. Immunoelectrophoresis

SummaryHost tissue reaction was a stumbling block in the progress of immunodiffusion and immunoelectrophoretic studies of arboviruses in this laboratory. Partial purification by flurocarbon or by protamine sulfate, of the infected rodent brain tissue homogenates used as test antigens or as inocula into rabbits to prepare antisera failed to remove the tissue antigen reactions. Antisera prepared against infected mouse brain or normal mouse brain reacted with normal hamster brain and vice versa. However, two methods were successful in eliminating the reaction: (i) Pellets obtained from clarified infected mouse brain homogenates following ultracentrifugation at 106,000g was free from rodent brain antigen but contained reacting viral antigens. (ii) Absorption of antisera either by 50% normal mouse brain or normal hamster brain eliminated the antibodies to the rodent brain tissue antigens. Two methods accomplished this latter—conventional tube absorption or absorption-in-gel. The latter is described in detail a...

Elimination of Host Tissue Reactions in Immunodiffusion and Immunoelectrophoretic Studies of Arboviruses

SummaryDengue type 2, New Guinea “C” virus, from a case of classical dengue fever was compared with dengue TH-36, an agent antigenically closely related to it but isolated from a case of hemorrhagic fever. Cross neutralization tests by the plaque method were performed in duplicate with essentially duplicate results. These were plotted and the 50% serum end points were determined. Relative potencies for homologous and heterologous serum-virus combination were calculated. Significant differences in degrees of neutralization of the two viruses were obtained, the homologous serum and virus resulting in the highest percentage plaque reduction at every serum dilution in each experiment. It is concluded that these two viruses differ antigenically as demonstrated in relatively precise quantitative tests, confirming previous differences shown by complement fixation, immunodiffusion, and immunoelectrophoresis.

Adly N. Ibrahim

Papers

Tumor-associated antigens in cervical cancer tissues and in sera from patients with cervical cancer or with head and neck cancer

Common Antigens of Herpes Simplex Virus 2, Associated Hamster Tumors, and Human Cervical Cancer

Application of Immunodiffusion Methods to the Antigenic Analysis of Dengue Viruses II. Immunoelectrophoresis

Elimination of Host Tissue Reactions in Immunodiffusion and Immunoelectrophoretic Studies of Arboviruses

Cross Plaque Neutralization of Two Antigenically Closely Related Dengue Viruses (Type 2 New Guinea C and TH-36)