Apparent Neutralization Research Articles

Kinetic mechanism for HIV-1 neutralization by antibody 2G12 entails reversible glycan binding that slows cell entry

Despite structural knowledge of broadly neutralizing monoclonal antibodies (NMAbs) complexed to HIV-1 gp120 and gp41 envelope glycoproteins, virus inactivation mechanisms have been difficult to prove, in part because neutralization assays are complex and were previously not understood. Concordant with recent evidence that HIV-1 titers are determined by a race between entry of cell-attached virions and competing inactivation processes, we show that NMAb 2G12, which binds to gp120 N-glycans with α (1, 2)-linked mannose termini and inhibits replication after passive transfer into patients, neutralizes by slowing entry of adsorbed virions. Accordingly, apparent neutralization is attenuated when a kinetically competing virus inactivation pathway is blocked. Moreover, removing 2G12 from media causes its dissociation from virions coupled to accelerated entry and restored infectivity, demonstrating the reversibility of neutralization. A difference between 2G12 dissociation and infectivity recovery rates implies that the inhibited complexes at virus-cell junctions contain several 2G12's that must dissociate before entry commences. Quantitative microscopy of 2G12 binding and dissociation from single virions and studies using a split CCR5 coreceptor suggest that 2G12 competitively inhibits interactions between gp120's V3 loop and the tyrosine sulfate-containing CCR5 amino terminus, thereby reducing assembly of complexes that catalyze entry. These results reveal a unique reversible kinetic mechanism for neutralization by an antibody that binds near a critical V3 region in the glycan shield of gp120.

Gestures in optimality theory and the laryngeal phonology of Faroese

This paper presents an Optimality Theoretic analysis of aspiration in the Scandinavian language Faroese using gestural score representations from Articulatory Phonology. In Faroese, a strong parallel exists between pre- and post-aspiration such that neither realization appears to be inherently preferred. This symmetry is straightforwardly captured by alignment within gestural scores, but runs counter to the treatments of pre-aspiration in traditional linear and autosegmental theories, where such segments are inherently more complex than their post-aspirated counterparts. An OT analysis that makes use of the alignment-based distinction in gestural scores is therefore proposed for the Faroese data. The account incorporates cross-linguistic preferences for post-aspiration and the correlation observed between stress and aspiration, yet pre-aspiration surfaces in many of the Faroese environments. Laryngeal alignment preferences are also analyzed as the basis of apparent contrast neutralization and sonorant devoicing in consonant sequences, and provide the framework for a grounded analysis of the interaction seen among consonant length, vowel quality and aspiration. Based on the analytic benefits of incorporating rich representational structure into the OT framework seen here and elsewhere, the potential for such theories to contribute to the advancement of phonological theory appears to be considerable.

The Structure of Water Induced by Specific Ceramics Treatment and Effects of Treated Water in View of Some Biological Aspects

The structure of water induced by a high-temperature sintered kaolinite ceramics treatment was studied in view of thermally stimulated depolarized current (J) and temperature profiles (TSDC analysis) on the iced treated water and 1H-Nuclear Magnetic Resonance (NMR) spectrometry on the treated water as well as some physical properties of the sintered ceramics. In addition, some biological effects of the treated water were examined to give indirect evidences for the proposed water structure. The treated water were positively charged based on essentially the formation of electric double layer interface between the ceramics surface and water flow, without any absorption-desorption phenomena to substances contained in water to be treated by the ceramics. The positive charge was indirectly affirmed by TSDC and 1H-NMR analyses on ionexchanged water and for the drinking water. The water structure derived by the existence of chlorine substances was apparently disappeared from 1H-NMR spectrum, probably by the apparent neutralization or accumulation of chlorine substances through interaction with positive charge. This phenomenon seemed to be closely related with the fact that absorption of chlorine ion through a vegetable root was greatly depressed when the treated water by the ceramics was used. The treated water was also proved to restrict the growth of E. coli in poor nutritional culture media and the production of bacterial cellulose by CFJ-002 (New bacterium cellulose-producing microorganism, an enterobacter) stock, and to suppress the oxidation action of hydrogen peroxide.

Desire, Duplicity and Narratology: Boris Vian's L 'Ecume des jours

In this examination of Boris Vian's L'Ecume des jours, I call into question the masculinist resistance to criticism of Vian and his works through a critical counter-resistance from a feminist narratological perspective. In order to examine the implications of "narrative desire" for understanding textual and sexual difference, I argue for a narratology that develops the concept of textual "seduction" as a question of narrative duplicity. I undertake this "re-reading" not merely from the perspective of an "ideological unmasking," but also to suggest the possibility of a positive hermeneutic, or more precisely, the limits of such a move given inherent difficulties evident in Vian's text. L'Ecume des jours provides the ground for reflections linking narratology to critical strategies that will enable me to pursue three lines of inquiry: first, how do the diegetic episodes depicting the parallel obsessions of the chief male protagonists, Colin and Chick, mask crucial questions of sexual difference in the story? Second, to what extent do the narrator's means of engaging the reader serve to actualize or obscure questions of sexual difference and narrative duplicity? Third, how does the novel's extensive recourse to dialogue contribute both to the occupation of the narrator's role and to the apparent neutralization of sexual differentiation?

Neutralization and inelastic scattering energy loss of low energy He + ions at InP(110) surfaces

The InP(110)-l × 1 surface is investigated with a high-resolution low energy ion scattering system. Attention is paid to the precise measurement of energy spectra of the scattered He + ions from indium atoms on the surface at incident energies ranging from 300 to 1300 eV. The single scattering peaks are found to be composed of two components (peaks P1 and P2) of which the energies are shifted toward the low side with respect to the binary elastic collision model. The peak P2 is concluded to be due to the ions which are neutralized in the incoming path and subsequently re-ionized in the violent collision. The energy shift of the peak P1 has a continuous character, showing a gradual increase with increasing incident ion energy. Apparent neutralization is observed for the ions incident along the channel direction [10] at the (110) surface, and this is discussed in connection with the continuous energy loss.

The extent of snowpack influence on water chemistry in a North Cascades Lake

Integrated snowpack samples and lakewater samples were collected from a low‐alkalinity watershed in the North Cascades in 1984 and 1985 and analyzed for inorganic chemical parameters. Mean concentrations of NO3− and SO4−2 from North Cascades snowpack were near 4.5 and 5.5 μeq L−1, respectively. Mean pH was 5.2–5.3. During melting, anion levels in the snowpack decreased and pH increased. By July, mean NO3− and SO4−2 concentrations were 0.32 and 1.73 μeq L−1, respectively, and mean pH was 5.48. Acid neutralizing capacity at the lake outlet during snowmelt was diluted to 50% of April premelt values. During snowmelt runoff there was no apparent neutralization of bicarbonate by strong acids. By comparing lakewater NO3− concentrations to snowpack concentrations, over 75% of the NO3− in the lake could be attributed to a snowpack source. An estimated 30% of the SO4−2 in the lake was derived from the snowpack.

Antigenic relationships among influenza virua A neuraminidase (N2) antigens by immunodiffusion and postinfection neutralization tests.

The antigenic relationships among the neuraminidases of influenza A strains from 1957 to 1973 were examined by postinfection application of neuraminidase antisera. This procedure causes inhibition of virus spread and apparent neutralization. Neuraminidase (apparent) neutralization and neuraminidase inhibition tests with chicken antisera gave similar results. Neuraminidase inhibition tests were more discriminating than neuraminidase neutralization tests when rabbit and goat antisera were used. Antibody absorption studies revealed that the neuraminidase, like the hemagglutinin, may possess two kinds of antigenic determinants, which can give rise to "common," or "cross-reacting," and "specific" antibodies. "Specific" antibody appears to be more effective in the inhibition of enzyme activity than in the inhibition of virus spread.

The mechanism of bacteriophage T4 neutralization: effects of univalent antibody fragments on T4 adsorption kinetics.

Bacteriophage T4 is neutralized by univalent antibody fragment Fab′ with apparent two-target neutralization kinetics. By the use of conditional lethal (amber) T4 mutants, it was shown that partially neutralized preparations of phages adsorb to bacteria with kinetics suggesting a mixture of fast and slow adsorbers; the ratio of fast to slow phages fits well that predicted by Poisson distribution of phages with, respectively, no (zero hit) and one (one hit) Fab′ complexed. A portion of the infectivity of one-hit phages seems due to phage–Fab′ dissociation, but the larger portion (80%) of the infectivity is due to weak adsorption of phages complexed still with one Fab′. It was shown that antibody to tail fiber is responsible for this effect. Phage adsorption heterogeneity was a possible explanation of kinetics obtained using phages which had not been treated with Fab′.

Serological relationships of Salmonella A bacteriophages isolated from salmonellae in different Kauffmann-White groups.

Six different Salmonella group A phages from salmonellae in Kauffmann- White groups B, C(1), C(2), and D were examined serologically. Those phages which were specific for a particular somatic antigen were found to be serologically very similar. Antiserum against a phage with one specificity was able to neutralize a different phage with the same specificity but unable to neutralize, in the normal way, a phage with a different specificity. Phages mixed with heterologous phage antiserum responded with an "inhibition response" in which there appeared to be a neutralization of the phage infectivity for the first 10 min, followed by a reversal of the neutralization until, by 20 or 25 min, there was no apparent neutralization. This response was interpreted to indicate that the adsorption antigens, probably situated on the tail fibers, were different for phages with different specificities but sufficiently similar so that heterologous antibodies could react with the antigens; but the antigen-antibody complex was quickly disassociated, resulting in a modification of the antibody molecules but no change in the specificity sites of the antigen. A subgrouping of the Salmonella A phages based on their antigenic specificity is suggested.

Alteration of corpus luteum function in the pregnant rat by antiluteinizing serum.

The effect of antibovine luteinizing hormone (LH) serum on the Δ5-3β-hydroxysteroid dehydrogenase (Δ5-3β-OHSDH) and the 20α-hydroxysteroid dehydrogenase (20α-OHSDH) activity in the ovaries of pregnant rats was studied and correlated with changes in the state of pregnancy. The apparent neutralization of LH during days 7–11 of pregnancy resulted in termination of the pregnancy by fetal reabsorption and the reappearance of strong 20a-OHSDH activity in the corpora lutea. Such an enzymatic reaction is not normally demonstrable at this time. Concomitantly, the Δ6-3β-OHSDH activity decreased below the normal expected values. Concurrent administration of progesterone prevented the effects of the anti-LH treatment. Neutralization of LH from the 12th to the 16th day of pregnancy led to similar results if the antiserum treatment was initiated on the morning of the 12th day of pregnancy. Later treatment, particularly from days 14–18, failed to affect either the normal development of the pregnancy or the normal pattern of enzyme activity. The importance of LH during early pregnancy and its role in the steroidogenic processes in the ovary are discussed in light of these findings. (Endocrinology 84: 244, 1969)

Preparation and Properties of Antibody Directed Specifically Against the Neuraminidase of Influenza Virus

Summary Antiserum was prepared against a recombinant influenza virus possessing A0 (NWS strain) type hemagglutinin and A2 (RI/5+) type neuraminidase. This antiserum was absorbed sequentially with NWS and A2 viruses and antibody directed against A2 type neuraminidase was then dissociated from the A2 virus. This antibody had no activity against the hemagglutinin activity of A0, A1 and A2 influenza viruses or against the infectivity of A0 and A1 viruses. It neutralized the enzyme activity of A2 but not A0 or A1 type influenza viruses. Anti-enzyme antibody caused apparent neutralization of the infectivity of influenza viruses possessing A2 type neuraminidase providing that the antibody was allowed to remain in contact with the cells during the test period. This antibody did not prevent infection of susceptible cells but apparently prevented the release of detectable levels of hemagglutinin. It had no effect on the infectivity of an A2 type recombinant virus that lacked neuraminidase activity.

Cooperative Jahn-Teller Distortions in the Systems ZnMn2O4–Cu2GeO4 and ZnMn2O4–ZnCuGeO4

Ionic distributions and cooperative J-T (Jahn-Teller) distortions are studied in the systems ZnMn2O4–Cu2GeO4 and ZnMn2O4–ZnCuGeO4 which contain both Cu2+ and Mn3+ ions. Cation distributions were determined by x-ray diffraction for Zn0.5Cu0.5[Ge0.5Cu0.5Mn]O4 and by neutron diffraction for Zn[CuGe]O4. The ionic distributions for the two systems were then taken to be Zn1−xCux [GexCuxMn2−2x]O4 and Zn[GexCuxMn2−2x]O4. In the first system, the axial ratio c/a was found to depend essentially on the Mn3+ content only. The equal distribution of the Cu2+ ions over the A and B lattice sites results in the apparent neutralization of contributions from Cu2+ ions to cooperative J-T distortions. In the second system J-T distortions at room temperature were observed to much lower concentrations of Mn3+ ions than for the first system. However, in spite of most of the Cu2+ ions being on the B sites, the Zn[CuGa]O4 end of the system was found to be cubic at room temperature. The cation distribution was determined with x-ray diffraction for Ga[CuGa]O4 which is also cubic.

An analysis of the apparent neutralization of rous sarcoma virus with antiserum to normal chick tissues

The effect of antiserum to normal chick embryo tissues on the infectivity assay of the Rous sarcoma virus was investigated. It was found that such serum, when mixed with the virus and inoculated on the chorioallantoic membrane (CAM) of the developing chick embryo, caused a sharp reduction in the number of virus-induced tumors when compared with a control containing normal serum. In contrast to neutralization with specific antiviral serum, however, the reaction required complement and was completely reversible on dilution of the serum-virus mixture. Furthermore, the anticell serum suppressed tumor formation even when added after virus had adsorbed to susceptible cells, whereas the antiviral serum was effective only before adsorption. Most of the tumor-inhibiting activity of the antichick serum could be removed by absorption with normal chick cells and to a lesser degree by absorption with sheep red blood cells. Moreover, antiserum to boiled sheep red blood cell stroma was also capable of reducing the number of tumors. The antichick serum had no significant effect on the assay of vaccinia virus on the chorioallantoic membrane. It was concluded that the apparent neutralization of Rous sarcoma virus by antichick serum was due to impairment of the ability of the infected cells to multiply rather than to a direct neutralization of virus itself. This contradicts some earlier reports which indicated that unaltered normal cell protein forms an integral part of the functional surface of the Rous sarcoma virus.