Enzyme-linked immunosorbent assay for mumps IgM antibody: comparison of IgM capture and indirect IgM assay

We have established two enzyme-linked immunosorbent assays (ELISAs) for detection of mumps IgM antibody, i.e., indirect IgM ELISA and IgM capture ELISA, for serodiagnosis of recent mumps infection. In the latter method, peroxidase-conjugated monoclonal antibody to mumps virus was employed. Both methods detected mumps antibody of IgM class only in serum fractions separated by centrifugation through a sucrose density gradient. Optical density values given by both ELISAs were correlated for most sera examined. Indirect IgM ELISA, however, gave a false positive reaction for sera containing both rheumatoid factor and mumps IgG antibody, while giving a false negative reaction for sera containing high titers of mumps IgG antibody. This technique was, therefore, less reliable than IgM capture ELISA. IgM antibody detectable by IgM capture ELISA was present in all patients with mumps by the fifth day of illness and persisted for up to 3 mth in most and up to 5 mth in same cases.

Interactions of formylamino- and methoxy-substituted beta-lactam antibiotics with beta-lactamases

Cephem and nocardicin-type monocyclic beta-lactam antibiotics with a formylamino substituent were highly resistant to hydrolysis by both penicillinases and cephalosporinases. Among antibiotics with a methoxy substituent, an N-sulfonated monocyclic beta-lactam antibiotic, sulfazecin was resistant to beta-lactamases, but cephem antibiotics were sensitive to the cephalosporinase of Enterobacter cloacae. The resistance of the antibiotics to the beta-lactamases depended primarily on the presence of the substituent, but affinity for the beta-lactamases was affected not only by the substituent but also by the presence of other side chains. Formylamino compounds and sulfazecin were as good inducers of beta-lactamases as semisynthetic 7-methoxycephalosporins, but naturally occurring 7-methoxycephalosporins were poor inducers. The inducer activities of the antibiotics were not necessarily related to their beta-lactamase stabilities. The stabilities of the compounds to the beta-lactamases were well reflected in their antibacterial activities against beta-lactamase producing bacteria.

Inability of Japanese rubella vaccines to induce antibody response in rabbits is due to growth restriction at 39 degrees C

We have compared the kinetic growth patterns of To-336, MEQ11, KRT, and SK2 rubella vaccine strains licensed in Japan at 37 degrees and 39 degrees C with those of progenitor wild strains of rubella virus. The growth of vaccine strains was depressed at 39 degrees C to a level about 3 log10 lower than that at 37 degrees C. The difference in virus titer attained by wild strains at 37 degrees and 39 degrees C was less than tenfold. The growth potential at 39 degrees C paralleled the immunogenic marker of rubella virus, i.e. the capability of virus to induce antibody response upon subcutaneous injection in rabbits for all wild and vaccine strains examined, including one strain at an intermediate level of attenuation. Several clones were isolated from the progeny produced by a vaccine strain during the growth at 39 degrees C. Among them were partial revertants in immunogenic marker as well as in the growth potential at 39 degrees C. It was concluded that the immunogenic marker of rubella virus in rabbits represented its capability to replicate at the body temperature of the animal.

Maturation of measles virus hemagglutinin glycoprotein

The processing of measles virus hemagglutinin glycoprotein (H) in infected cells was studied by pulse-chase method and two-dimensional isoelectric focusing and SDS-polyacrylamide slab gel electrophoresis. H glycoprotein was synthesized initially as polypeptides smaller than H glycoprotein present in the virions. They were then processed into a cohort of polypeptides of larger molecular size and with reduced charge. The change was associated with the expression of H glycoprotein on the cell surface. The removal of sialic acid from carbohydrate chain of H glycoprotein resulted in the shift of isoelectric point to a more basic range. The entire process of maturation of H glycoprotein required approximately 5 hours. Carbohydrate content in H was determined to be approximately 12 per cent by weight. Mannose, galactose, fucose, N-acetylglucosamine, and N-acetylneuraminic acid were the constituent monosaccharides.

Effect of beta-lactamase induction on susceptibility to cephalosporins in Enterobacter cloacae and Serratia marcescens

For Enterobacter cloacae GN5797 and Serratia marcescens 72-2, which produce inducible beta-lactamases and respond antagonistically to many combinations of cephalosporins, the changes in beta-lactamase activity and sensitivity to cephalosporins were examined during semi-continuous cultivation in which the concentration of inducers was decreased by two-fold dilution of the culture every 30 min starting from 1 h after the addition of inducers. The levels of beta-lactamase, which peaked at 0.5-2 h after induction, decreased concomitantly with the disappearance of the inducers in the culture, and returned to the uninduced levels by 6 h. The ability of cefoxitin and cefmetazole to induce beta-lactamases was more potent than that of cefazolin and cefotiam. The sensitivity to some cephalosporins, judged by the MIC and bactericidal effect, was slightly decreased at an early stage of induction, and reverted to the uninduced levels within several hours after the inducers were depleted.

Characterization of major structural proteins of measles virus with monoclonal antibodies

We have prepared and characterized monoclonal antibodies against five major structural proteins, i.e. the HA, P, NP, F and M proteins, of measles virus. At least three non-overlapping antigenic sites were delineated on the HA protein, three on the P, four on the NP, four on the F and five on the M proteins by competitive binding assays. Antigenic sites on the HA and F proteins roughly represented functional domains defined by serological tests. The reactivity of monoclonal antibodies with various measles virus strains including those from subacute sclerosing panencephalitis (SSPE) and other members of the morbillivirus family was studied by immunofluorescence. A monoclonal antibody or set of monoclonal antibodies to each of the antigenic sites showed a characteristic pattern of cross-reactivity with heterologous strains. The HA and NP proteins were antigenically the most variable, followed by the F and M proteins, while the P protein was relatively stable. None of the 14 anti-M monoclonal antibodies reacted with non-virus-producing SSPE cells, strongly suggesting the absence of M protein in these cells.

Renal function during application of positive end-expiratory pressure in swine: effects of hydration

The possibility that the deleterious renal effects of positive end-expiratory pressure (PEEP) might be avoided by prevention of its attendant cardiovascular effects with increasing intravascular volume was investigated in two groups of anesthetized swine. Group 1 (12 swine) were maintained at a normovolemic state and Group 2 (11 swine) were volume expanded with an infusion of lactated Ringer's solution. In normovolemic swine (Group 1), the addition of PEEP to controlled mechanical ventilation (CMV) caused significant decreases in cardiac output and mean aortic pressure. In addition, decreases in urinary output and osmolar, free water, and creatinine clearance occurred. Change from CMV to CMV + PEEP in Group 1 also produced increases in plasma ADH from 4.6 +/- 2.4 to 10.2 +/- 7 pg/ml (P less than 0.01) and renin from 1.8 +/- 1.0 to 4.7 +/- 1.6 ng X ml-1 X h-1 (P less than 0.01), epinephrine from 133 +/- 23 to 1,060 +/- 636 pg/ml (P less than 0.03) and norepinephrine from 46 +/- 15 to 1,427 +/- 839 pg/ml (P less than 0.03). In hydrated swine (Group 2) addition of PEEP to CMV was not accompanied by any significant change in hemodynamic, renal, or hormonal variables. It is concluded that the short-term renal effects of PEEP are mainly due to hormonal responses that are activated by decrease in perfusion pressure. These responses can be obviated by intravascular volume expansion.

Monoclonal antibodies directed to E1 glycoprotein of rubella virus

We have prepared four monoclonal antibodies to rubella virus E1 glycoprotein. Three nonoverlapping antigenic sites were delineated on E1 protein by competitive binding assays. Antibodies binding to one site were characterized by high hemagglutination inhibition (HI) titer but poor neutralizing activity. The addition of antiglobulin conferred neutralizing activity. Antibodies directed to two other antigenic sites had modest hemolysis inhibition but little or no HI and neutralizing activities. The addition of antiglobulin markedly augmented HI activity but had little effect on neutralizing activity. Epitopes defined by three antibodies were conserved among four rubella virus strains examined.

Antibody response to individual rubella virus proteins in congenital and other rubella virus infections

Serum samples from patients with various forms of rubella virus infection were tested for antibodies to each of three viral structural proteins by radioimmunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In most sera antibody to E1 protein was the predominant species. Sera from patients with congenital rubella syndrome, however, contained significantly more E2 antibody relative to E1 antibody than did sera from other rubella patients.

Physiological characterization of influenza virus temperature-sensitive mutants defective in the haemagglutinin gene

We have characterized the physiological defect in two temperature-sensitive mutants of the WSN strain of influenza virus which possessed a lesion in the haemagglutinin (HA) gene. In mutant virus-infected cells at the non-permissive temperature, the precursor HA polypeptide containing predominantly mannose-rich carbohydrate chains was not converted to the mature, functional HA polypeptide. Immunofluorescence showed that the HA polypeptide did not appear on the cell surface but was confined largely to the Golgi apparatus. It was concluded that the major physiological defect of these mutants was a block in the transport of the HA polypeptide beyond the Golgi apparatus. The block could be reversed, however, by lowering the temperature to 34 degrees C, resulting in normal processing of the precursor polypeptide and emergence of infectious progeny virus within 30 min. The HA activity of the two mutants, but not wild-type virus, was rapidly inactivated at 51 degrees C. Most, but not all, revertants derived from these mutants had HA with the heat stability of wild-type virus, suggesting that the temperature sensitivity and the heat lability of HA were two pleiotropic manifestations of a single lesion in the HA gene.

Biological functions of monospecific antibodies to envelope glycoproteins of Newcastle disease virus

Monospecific antisera to HN and F glycoproteins of Newcastle disease virus were prepared, and their effects on the biological activities of the virus were investigated. Anti-HN serum inhibited hemagglutinating and neuraminidase activity, as well as hemolysis. Anti-F serum had no effect on hemagglutination or neuraminidase but inhibited hemolysis and virus-induced cell fusion. Anti-HN serum was highly neutralizing, while neutralization by anti-F serum was very inefficient in conventional plaque reduction tests, although both sera were estimated to contain comparable amounts of antibody reacting with the virus as indicated by complement fixation and immuno-diffusion tests. The neutralizing activity of anti-F serum was greatly enhanced by the addition of anti-IgG serum or fresh guinea pig serum, whereas that of anti-HN serum was little enhanced. Anti-HN serum incorporated in the agar overlay suppressed the development of plaques to some degree, while anti-F serum had little effect. The combination of anti-HN and anti-F sera resulted in a marked decrease in the number and size of plaques, demonstrating the synergistic effect of the two species of antibody in the containment of the spread of viral infection.

Enzyme-linked immunosorbent assay compared with neutralization tests for evaluation of live mumps vaccines

Mumps-specific antibody levels before and after vaccination with live mumps vaccines were determined by enzyme-linked immunosorbent assay (ELISA) and neutralization tests. A correlation was found between neutralization titers and optical density in ELISA. However, postvaccination sera from some vaccinees who failed to seroconvert by neutralization contained significant levels of mumps-specific antibody detectable by ELISA. In some of these serum specimens, the antibody directed to the F polypeptide of mumps virus was predominant. Most sera positive in ELISA neutralized mumps virus upon the addition of fresh guinea pig serum to the virus-serum mixture.

Temperature-dependent growth restriction in measles vaccine strains

Temperature-dependent growth restriction was studied with the measles vaccine strains licensed in Japan in comparison with their parental wild strains. Plaquing efficiency was compared at various temperatures from 35 to 40 C. AIK-C strain derived from Edmonston wild strain was temperature-sensitive with the 39 C shutoff temperature. No significant restriction of growth was found for other vaccine strains, i.e., Schwarz, FF-8, and CAM-70, and for their parental wild strains, i.e., Edmonston and Tanabe . A paradoxical feature was found for FF-8 strain; in spite of undiminished plaquing efficiency at 40 C, the growth in the fluid medium was markedly depressed at 39 C or above.

Potentiation of natural killer cell activity of human lymphocytes in vitro: the participation of interferon in stimulation with Staphylococcus aureus Cowan I bacteria but not with protein A

In the previous paper we reported that human natural killer (NK) cell activity was augmented greatly by preincubation with Staphylococcus aureus Cowan I bacteria (SpA CoI) or its Protein A. We examined here whether the augmentation with these stimulants is ascribable to the direct activation of NK cells or mediated by some soluble factors produced by the stimulants. It was found that a significant amount of interferon (IFN) was produced by the SpA CoI-stimulation but not by the Protein A-stimulation, although the latter usually induced augmentation of NK-cell activity not less than SpA CoI-stimulation. IFN produced by SpA CoI was considered to belong to alpha-type IFN, because it was stable at pH 2.0 and could be neutralized effectively by anti-IFN alpha antibody. Kinetics of NK-cell activation by SpA CoI (but not by Protein A) were very similar to those by IFN alpha. Furthermore, augmentation of NK-cell activity with SpA CoI-stimulated supernatant was inhibited almost completely by diluted anti-IFN alpha antibody, whereas augmentation with Protein A-stimulated supernatant could not be abolished by the same treatment. It was, therefore, suggested that augmentation of NK-cell activity with SpA CoI might be ascribable in most part to the IFN induced, whereas Protein A can stimulated NK or T cells directly or soluble factors other than IFN might work as well.

Influenza surveillance based on oligonculeotide mapping of RNA of H1N1 viruses prevalent in Japan, 1978-1979

Influenza H1N1 viruses isolated in Japan in 1978-1979 were compared with A/USSR/92/77 and H1N1 viruses isolated in North and South America in 1978 by oligonucleotide mapping of viral RNA. At least four types of H1N1 viruses, distinguished by oligonucleotide pattern, were involved in influenza outbreaks during 1978-1979 in Japan. The first type was prevalent throughout the country from January to March 1978. The second and third types caused sporadic outbreaks during the 1978-1979 winter. The second type was closely related to an H1N1 strain of 1953, A/Omachi/1/53; the third type appeared to be reintroduced from outside of Japan. The fourth type was prevalent from January 1979 and persisted to September 1979. Its origin was a virus closely related to A/California/45/78 virus, which appeared in the United States in late 1978. The oligonucleotide pattern of A/California/45/78 viral RNA was markedly different from that of other 1977-1978 H1N1 viruses; the major change occurred in the polymerase and nucleoprotein genes.

Extra RNAs of von Magnus particles of influenza virus cause reduction of particular polymerase genes

Extra RNAs, or RNA species other than eight gene segments, in von Magnus particles of the influenza virus WSN strain were studied by polyacrylamide gel electrophoresis and oligonucleotide mapping. From the original virus stock, various cloned stocks were obtained, each giving rise to a characteristic set of extra RNAs. One cloned virus stock contained a large number of von Magnus particles. The RNA pattern was characterized by two prominent extra RNAs (X1 and X2) and a decrease in the content of two polymerase genes, P1 and P2. Segregation of the two extra RNAs was carried out by coinfection of cells with a von Magnus particle and infectious virions. The results showed that the presence of one of the extra RNAs (X2) was associated with a reduction in the amount of the P1 gene and that the presence of the other extra RNA (X1) was associated with a reduction in the amount of the P2 gene. Oligonucleotide mapping showed that both extra RNAs, X1 and X2, were derived from the P1 gene. The results suggested that an extra RNA did not necessarily cause the reduction of the progenitor polymerase gene, but might cause the reduction of another polymerase gene.

Origin of small RNA in von Magnus particles of influenza virus

A clone of recombinant virus obtained from the cross between WSN and Hong Kong strains of influenza virus gave rise to progeny containing predominantly von Magnus particles. In the electropherogram of virus RNA, the P3 gene was markedly diminished, and a new species of RNA (extra RNA) was present in addition to eight gene segments. The origin of the extra RNA was studied by two-dimensional gel electrophoresis of T1 RNase-generated oligonucleotides. Four out of five large oligonucleotide spots present in the extra RNA matched to those contained by the P3 gene. It was concluded that the extra RNA was derived from the P3 gene probably by deletion. The possible origin of the spot which was present in the extra RNA but not in eight gene segments including P3 was discussed.

Virus plaque assay: effective detection of virus plaque forming cells at the early stage of lymphocyte activation by mitogen and alloantigen

Activated lymphocytes were detected quantitatively by virus plaque assay (VPA) during the course of lymphocyte cultures stimulated by mitogen or alloantigen. In Con A-stimulated cultures, the number of virus-plaque forming cells (V--PFC) was a more sensitive method of detecting the early stage of lymphocyte activation than [3H]-thymidine (3H-TdR) incorporation. This evidence was obtained by two methods of collecting cells of each stage. First, when Con A-activated lymphocytes were fractionated by velocity sedimentation at unit gravity to separate cell populations according to each cell stage, the ratio of the number of V-PFC to the radioactivity of incorporated [3H]-TdR was larger in the earlier stage of cell cycle than in the later stage. Second, when cultured lymphocytes were synchronized directly by addition of excess thymidine and colchicine, similar results were obtained. In primary mixed lymphocyte cultures, the generation of cytotoxic lymphocytes (CTL) was correlated better with the proliferative response than with V-PFC production. It was also found that both the incorporation of [3H]-TdR and the generation of CTL were abrogated by cytosine arabinoside (Ara-C) added to cultures up to one day before assay, whilst the generation of V-PFC was not so markedly affected by Ara-C. These findings suggest that V-PFC represent the number of precursor cells which require one or more generations to differentiate to CTL and not simply the number of effector lymphoyctes already exhibiting cytotoxicity.

Identification of hemagglutinin and neuraminidase genes of influenza B virus

The genome of influenza B viruses was shown by electrophoresis to consist of eight RNA segments. The fifth largest segment coded for hemagglutinin and the sixth coded for neuraminidase.