Interaction among deer in a chronic wasting disease endemic zone

Although it is known that chronic wasting disease (CWD) can be transmitted by both direct animal-to-animal contact and contact with contaminated environments, the relative role of each mechanism in the spread of CWD in free-ranging populations has yet to be defined. We investigated patterns of interaction between mule deer (Odocoileus hemionus) in order to understand how factors such as season and landscape may influence patterns of disease spread in these populations. Using location data from male and female Global Positioning System (GPS)-collared mule deer in 5 study areas located in and around a CWD-endemic zone in southern Saskatchewan, Canada, we quantified close proximity events, or events involving both spatial and temporal overlap of individuals. We defined close proximity events as occurrences in which 2 deer were located <25 m apart at the same point in time. We looked at seasonal variation in the probability of close proximity events, as well as landscape factors associated with these events when compared to areas of shared space use, or spatial overlap alone. Overall probability of an individual GPS-collared deer being located in close proximity to another GPS-collared deer was 0.092 (n = 107). The early gestation (16 Dec–31 Mar) and late gestation (1 Apr–15 May) seasons had the highest probability of close proximity events occurring, and same-sex pairs were more likely to be found in close proximity than between-sex pairs during all seasons aside from the rut (1 Nov–15 Dec). High probability of close proximity events during the gestation seasons agrees with the tendency of mule deer to aggregate into large groups during late winter and suggests that this may be an important time period for CWD transmission to occur. Close proximity events occurred more in cropland and wetland than expected based on availability, whereas close proximity events occurred less than expected in grassland. The opposite was true for spatial overlap between individuals, which occurred more than expected in areas of low elevation and rugged terrain and in grassland or shrub–wood habitats. These results suggest that cropland may be a higher risk habitat for direct and indirect CWD transmission between individuals and that, although coulees and other areas of rugged topography are less likely to be associated with close proximity events, those areas may be more likely to contain environmental contamination in CWD-affected areas due to common use by multiple deer. © 2011 The Wildlife Society.     

Comparison of the Fc glycosylation of fetal and maternal immunoglobulin G

Human immunoglobulin G (IgG) molecules are composed of two Fab portions and one Fc portion. The glycans attached to the Fc portions of IgG are known to modulate its biological activity as they influence interaction with both complement and various cellular Fc receptors. IgG glycosylation changes significantly with pregnancy, showing a vast increase in galactosylation and sialylation and a concomitant decrease in the incidence of bisecting GlcNAc. Maternal IgGs are actively transported to the fetus by the neonatal Fc receptor (FcRn) expressed in syncytiotrophoblasts in the placenta, providing the fetus and newborn with immunological protection. Two earlier reports described significant differences in total glycosylation between fetal and maternal IgG, suggesting a possible glycosylation-selective transport via the placenta. These results might suggest an alternative maternal transport pathway, since FcRn binding to IgG does not depend on Fc-glycosylation. These early studies were performed by releasing N-glycans from total IgG. Here, we chose for an alternative approach analyzing IgG Fc glycosylation at the glycopeptide level in an Fc-specific manner, providing glycosylation profiles for IgG1 and IgG4 as well as combined Fc glycosylation profiles of IgG2 and 3. The analysis of ten pairs of fetal and maternal IgG samples revealed largely comparable Fc glycosylation for all the analyzed subclasses. Average levels of galactosylation, sialylation, bisecting GlcNAc and fucosylation were very similar for the fetal and maternal IgGs. Our data suggest that the placental IgG transport is not Fc glycosylation selective.     

The Fab Conformations in the Solution Structure of Human Immunoglobulin G4 (IgG4) Restrict Access to Its Fc Region: IMPLICATIONS FOR FUNCTIONAL ACTIVITY*

Human IgG4 antibody shows therapeutically useful properties compared with the IgG1, IgG2, and IgG3 subclasses. Thus IgG4 does not activate complement and shows conformational variability. These properties are attributable to its hinge region, which is the shortest of the four IgG subclasses. Using high throughput scattering methods, we studied the solution structure of wild-type IgG4(Ser²²²) and a hinge mutant IgG4(Pro²²²) in different buffers and temperatures where the proline substitution suppresses the formation of half-antibody. Analytical ultracentrifugation showed that both IgG4 forms were principally monomeric with sedimentation coefficients s_20,w⁰ of 6.6–6.8 S. A monomer-dimer equilibrium was observed in heavy water buffer at low temperature. Scattering showed that the x-ray radius of gyration R_g was unchanged with concentration in 50–250 mm NaCl buffers, whereas the neutron R_g values showed a concentration-dependent increase as the temperature decreased in heavy water buffers. The distance distribution curves (P(r)) revealed two peaks, M1 and M2, that shifted below 2 mg/ml to indicate concentration-dependent IgG4 structures in addition to IgG4 dimer formation at high concentration in heavy water. Constrained x-ray and neutron scattering modeling revealed asymmetric solution structures for IgG4(Ser²²²) with extended hinge structures. The IgG4(Pro²²²) structure was similar. Both IgG4 structures showed that their Fab regions were positioned close enough to the Fc region to restrict C1q binding. Our new molecular models for IgG4 explain its inability to activate complement and clarify aspects of its stability and function for therapeutic applications.     

The role of immunoglobulins in immunity to Trypanosoma brucei gambiense

The effects of IgM and IgG antibody molecules were compared on a weight basis by both agglutination and in vitro protection tests. It was shown that IgM is a better agglutinating antibody and in the presence of complement is also a better neutralizing antibody. However, when IgM and IgG were tested for their ability to passively protect infected animals, it was noted that the IgG fraction appeared to give greater protection. Based on differences in diffusion coefficients (and size) of the molecules, it is hypothesized that IgM is the antibody class responsible for the relapse phenomena observed in the blood, while, it is the IgG antibody molecule which is more active in extravascular locations.     

The end-to-end distance of RNA as a randomly self-paired polymer

In this paper, we present the end-to-end distance of randomly self-paired polymers (RSPPs). We define a randomly self-paired polymer as a linear polymer each of whose monomers has a probability, f(0<f<1), of pairing with any other one monomer. The RSPP model is inspired by numerous observations that the ends of RNAs are in close proximity. We use this model to explain this proximity. The prediction made by the RSPP model is consistent with these observations. Mapping an RNA with a length of 1000 nucleotides and a pairing fraction of 0.6 onto our RSPP model, for example, we predict an expected end-to-end distance of about 14 unpaired bases. We have also found that the expected end-to-end distance of the RSPP scales roughly as the 1/4 power of its total length.     

Chromosomes of the caryophyllidean tapeworm Glaridacris laruei

The chromosomes of the monozoic tapeworm Glaridacris laruei, from 4 locations in New York State, were studied in leucobasic fuchsin stained squashes of testes and vitelline cells. The diploid chromosome number is 16. Metaphase figures from vitelline cells consist of 3 pairs of metacentrics (“V's”), 4 pairs of acrocentrics (“rods”), and 1 pair of submetacentrics (“J's”). The complement is characterized by a pair of metacentrics 9 μm long, representing 11.5% of the total chromosome length. The shortest are acrocentrics, 2–4 μm long. Meiosis was observed only in spermatogenesis, which proceeds as usual with normal sperm formed after 2 meiotic divisions. Colchicine pretreatment did not facilitate analysis of chromosomes. The scarcity of cell division in 2 populations of G. laruei suggests a possible mitotic rhythm or temperature effect on cell division. Similarities were observed between the the complements of G. laruei and Hunterella nodulosa (2n = 14). A theoretical idiogram, constructed from that of G. laruei, closely resembles H. nodulosa, indicating that there may be a close cytological relationship between these phenotypically different caryophyllids. An idiogram and photographs of chromosomes supplement the paper.     

Broad Spectrum Pro-Quorum-Sensing Molecules as Inhibitors of Virulence in Vibrios

Quorum sensing (QS) is a bacterial cell-cell communication process that relies on the production and detection of extracellular signal molecules called autoinducers. QS allows bacteria to perform collective activities. Vibrio cholerae, a pathogen that causes an acute disease, uses QS to repress virulence factor production and biofilm formation. Thus, molecules that activate QS in V. cholerae have the potential to control pathogenicity in this globally important bacterium. Using a whole-cell high-throughput screen, we identified eleven molecules that activate V. cholerae QS: eight molecules are receptor agonists and three molecules are antagonists of LuxO, the central NtrC-type response regulator that controls the global V. cholerae QS cascade. The LuxO inhibitors act by an uncompetitive mechanism by binding to the pre-formed LuxO-ATP complex to inhibit ATP hydrolysis. Genetic analyses suggest that the inhibitors bind in close proximity to the Walker B motif. The inhibitors display broad-spectrum capability in activation of QS in Vibrio species that employ LuxO. To the best of our knowledge, these are the first molecules identified that inhibit the ATPase activity of a NtrC-type response regulator. Our discovery supports the idea that exploiting pro-QS molecules is a promising strategy for the development of novel anti-infectives.     

An antibody cross-reacting with LA and FOUR antigens of theHL-A system

A volunteer was immunized by planned blood transfusions from an LA and FOUR incompatible donor. Among the several antibodies produced, an antibody population was found that cross-reacts with both LA and FOUR antigens; both these crossreacting determinants were present in the immunizing donor. Monospecificity of the antibody has been proven by adsorptions and elutions. Resistance to lysis experiments excluded the possibility that this antibody does not react against LA and FOUR, but reacts instead against an antigen belonging to another independentHL-A locus with alleles in strong linkage disequilibrium withLA andFOUR alleles. The following hypotheses are therefore formulated: a)LA andFOUR factors have structural analogies; b) LA and FOUR molecules lie in close proximity on the cell surface so that the appearance of a “hybrid” antigenic determinant becomes possible.     

UDP-galactose (SLC35A2) and UDP-N-acetylglucosamine (SLC35A3) Transporters Form Glycosylation-related Complexes with Mannoside Acetylglucosaminyltransferases (Mgats)

UDP-galactose transporter (UGT; SLC35A2) and UDP-N-acetylglucosamine transporter (NGT; SLC35A3) form heterologous complexes in the Golgi membrane. NGT occurs in close proximity to mannosyl (α-1,6-)-glycoprotein β-1,6-N-acetylglucosaminyltransferase (Mgat5). In this study we analyzed whether NGT and both splice variants of UGT (UGT1 and UGT2) are able to interact with four different mannoside acetylglucosaminyltransferases (Mgat1, Mgat2, Mgat4B, and Mgat5). Using an in situ proximity ligation assay, we found that all examined glycosyltransferases are in the vicinity of these UDP-sugar transporters both at the endogenous level and upon overexpression. This observation was confirmed via the FLIM-FRET approach for both NGT and UGT1 complexes with Mgats. This study reports for the first time close proximity between endogenous nucleotide sugar transporters and glycosyltransferases. We also observed that among all analyzed Mgats, only Mgat4B occurs in close proximity to UGT2, whereas the other three Mgats are more distant from UGT2, and it was only possible to visualize their vicinity using proximity ligation assay. This strongly suggests that the distance between these protein pairs is longer than 10 nm but at the same time shorter than 40 nm. This study adds to the understanding of glycosylation, one of the most important post-translational modifications, which affects the majority of macromolecules. Our research shows that complex formation between nucleotide sugar transporters and glycosyltransferases might be a more common phenomenon than previously thought.     

C3b/iC3b Deposition on Streptococcus pneumoniae Is Not Affected by HIV Infection

Streptococcus pneumoniae is a common cause of infection in both HIV positive patients and those with complement deficiencies. We hypothesised that HIV positive individuals might exhibit reduced opsonisation of pneumococcus with complement due to reduced levels of S. pneumoniae specific IgG. We discovered no difference in C3 deposition on S. pneumoniae between HIV positive or negative individuals, and furthermore C3 deposition remained unchanged as HIV progressed towards AIDS. We found no correlation between C3 deposition on S. pneumoniae and CD4 cell count in HIV infected individuals. Hence we have demonstrated no failure of complement immunity in HIV positive patients.     

Interaction of monocytes with tumor cells coated with complement with or without antibody

Raji, a human B lymphoblastoid cell line has the ability to activate the complement cascade by alternate pathway mechanisms with subsequent fixation of C3 to receptors on the Raji cell membrane. Using this property, we examined the role that complement plays in mediating a cytolytic event between human peripheral blood monocytes and Raji cells coated with C3b, antibody, or both. Presence of C3 was confirmed by immune adherence. IgG bound to the Raji membrane was quantitated using I¹²⁵ Staphylococcal protein A assay. The presence of alternate pathway-activated C3 on Raji cells failed to produce monocyte-mediated cytotoxicity. These same target cells subsequently coated with antibody concentration ranging from 200 to >600,000 SPA molecules per Raji cell produced neither enhancement nor inhibition of antibody-dependent, cell-mediated cytotoxicity (ADCC). ADCC was enhanced by complement when complement activation and binding of C3 to the cell surface occurred by classical pathway mechanisms. ADCC of 32% ± 3.2 occurred with undiluted antiserum (625,000 SPA molecules bound/Raji cell) with enhancement to 52% ± 1.1 in the presence of C3. IgG inhibition of ADCC was unaffected by the presence of membrane-bound C3.     

Neutralization of Chlamydia psittaci with Monoclonal Antibodies

Neutralization of Chlamydia (C.) psittaci avian strain P-1041 was examined in vitro using monoclonal antibodies (MAbs). Of the 10 MAbs used, 6 were found to exhibit neutralizing capability. These include 3 against major outer membrane protein (MOMP), 1 against lipopolysaccharide (LPS) and 2 against other protein molecules [90 kilodalton (kDa) and 90/50 kDa]. Most neutralizing MAbs were dependent on complement for efficient neutralization, while a strain-specific MAb (2B5) against the 90 kDa protein displayed a different requirement for complement and neutralized the infectivity of the P-1041 at high concentrations without complement. By competitive inhibition enzyme-linked immunosorbent assay (competitive inhibition ELISA), all 3 neutralizing anti-MOMP MAbs were demonstrated to recognize different epitopes found in very close proximity to each other on the outer membrane.     

Forced proximity promotes the formation of enduring cooperative relationships in vampire bats

Spatial assortment can be both a cause and a consequence of cooperation. Proximity promotes cooperation when individuals preferentially help nearby partners, and conversely, cooperation drives proximity when individuals move towards more cooperative partners. However, these two causal directions are difficult to distinguish with observational data. Here, we experimentally test if forcing randomly selected pairs of equally familiar female common vampire bats (Desmodus rotundus) into close spatial proximity promotes the formation of enduring cooperative relationships. Over 114 days, we sampled 682 h of interactions among 21 females captured from three distant sites to track daily allogrooming rates over time. We compared these rates before, during and after a one-week period, during which we caged random triads of previously unfamiliar and unrelated vampire bats in proximity. After the week of proximity when all bats could again freely associate, the allogrooming rates of pairs forced into proximity increased more than those of the 126 control pairs. This work is the first to experimentally demonstrate the causal effect of repeated interactions on cooperative investments in vampire bats. Future work should determine the relative importance of mere association versus interactions (e.g. reciprocal allogrooming) in shaping social preferences.     

Species-specific patterns of nonapeptide brain gene expression relative to pair-bonding behavior in grouping and non-grouping cichlids

Comparative studies have revealed that vasopressin–oxytocin pathways are associated with both pair bonding and grouping behavior. However, the relationship between pair bonding and grouping behavior remains unclear. In this study, our aim was to identify whether two species that differ in grouping behavior display a corresponding difference in their pair bonds, and in the underlying vasopressin–oxytocin hormonal pathways. Using two species of cichlid fishes, the highly social Neolamprologus pulcher and the non-social Telmatochromis temporalis, we measured proximity of pairs during pair bond formation, and then measured social behaviors (proximity, aggression, submission, affiliation) and brain gene expression of isotocin and arginine vasotocin (the teleost homologues of oxytocin and vasopressin, respectively), as well as their receptors, after a temporary separation and subsequent reunion of the bonded pairs. Pairs of the social species spent more time in close proximity relative to the non-social species. Rates of aggression increased in both species following the separation and reunion treatment, relative to controls that were not separated. Overall, whole brain expression of isotocin was higher in the social species relative to the non-social species, and correlated with proximity, submission, and affiliation, but only in the social species. Our results suggest that both a social and a non-social cichlid species have similar behavioral responses to a temporary separation from a mate, and we found no difference in the brain gene expression of measured hormones and receptors based on our separation–reunion treatment. However, our results highlight the importance of isotocin in mediating submissive and affiliative behaviors in cichlid fishes, and demonstrate that isotocin has species-specific correlations with socially relevant behaviors.     

Effects of Streptococcus pneumoniae strain background on complement resistance

Background

Immunity to infections caused by Streptococcus pneumoniae is dependent on complement. There are wide variations in sensitivity to complement between S. pneumoniae strains that could affect their ability to cause invasive infections. Although capsular serotype is one important factor causing differences in complement resistance between strains, there is also considerable other genetic variation between S. pneumoniae strains that may affect complement-mediated immunity. We have therefore investigated whether genetically distinct S. pneumoniae strains with the same capsular serotype vary in their sensitivity to complement mediated immunity.

Methodology and Principal Findings

C3b/iC3b deposition and neutrophil association were measured using flow cytometry assays for S. pneumoniae strains with different genetic backgrounds for each of eight capsular serotypes. For some capsular serotypes there was marked variation in C3b/iC3b deposition between different strains that was independent of capsule thickness and correlated closely to susceptibility to neutrophil association. C3b/iC3b deposition results also correlated weakly with the degree of IgG binding to each strain. However, the binding of C1q (the first component of the classical pathway) correlated more closely with C3b/iC3b deposition, and large differences remained in complement sensitivity between strains with the same capsular serotype in sera in which IgG had been cleaved with IdeS.

Conclusions

These data demonstrate that bacterial factors independent of the capsule and recognition by IgG have strong effects on the susceptibility of S. pneumoniae to complement, and could therefore potentially account for some of the differences in virulence between strains.     

Con A induced suppressor cells: suppression with I region incompatibility.

Allogeneic Con A induced suppressor cells differing in the I and S region but not H-2K or H-2D regions were as efficient as syngeneic cells in suppressing the secondary IgM and IgG response to burro erythrocytes. Con A activated suppressor cells were not sensitive to anti-Ia serum and complement. However, if the spleen cell population was treated with anti-Ia serum and complement before stimulation with Con A, suppressor cells were not generated.     

Piliation of Lactobacillus rhamnosus GG Promotes Adhesion,Phagocytosis, and Cytokine Modulation in Macrophages

Recently, spaCBA-encoded pili on the cell surface of Lactobacillus rhamnosus GG were identified to be key molecules for binding to human intestinal mucus and Caco-2 intestinal epithelial cells. Here, we investigated the role of the SpaCBA pilus of L. rhamnosus GG in the interaction with macrophages in vitro by comparing the wild type with surface mutants. Our results show that SpaCBA pili play a significant role in the capacity for adhesion to macrophages and also promote bacterial uptake by these phagocytic cells. Interestingly, our data suggest that SpaCBA pili also mediate anti-inflammatory effects by induction of interleukin-10 (IL-10) mRNA and reduction of interleukin-6 (IL-6) mRNA in a murine RAW 264.7 macrophage cell line. These pili appear to mediate these effects indirectly by promoting close contact with the macrophages, facilitating the exertion of anti-inflammatory effects by other surface molecules via yet unknown mechanisms. Blockage of complement receptor 3 (CR3), previously identified to be a receptor for streptococcal pili, significantly decreased the uptake of pilus-expressing strains in RAW 264.7 cells, while the expression of IL-10 and IL-6 mRNA by these macrophages was not affected by this blocking. On the other hand, blockage of Toll-like receptor 2 (TLR2) significantly reduced the expression of IL-6 mRNA irrespective of the presence of pili.     

Use of glutaraldehyde-fixed Escherichia coli cells as a convenient support for radioimmune assays.

Escherichia coli were activated by incubation with 1% glutaraldehyde, and the activated bacteria were then conjugated by incubation with IgG. About 66,000 molecules of IgG were bound per cell. The Escherichia coli-antibody conjugates were then used in competitive radioimmune assays. When a specific IgG fraction was used to prepare the conjugate, each cell bound about 16,000 molecules of antigen. With an antigen which had a specific activity of about 300 cpm/ng (or about 4.8 × 10⁴ cpm/pmol), the assay was linear over a range of 40–300 ng/ml (0.3–2.0 pmol/ml). About 100 samples were assayed per day.     

The nucleotide sequency of tRNA Gly from yeast

Analysis of the factor for proximity and orientation is given for cyclopentadiene dimerization and for the general case of more complex biological molecules. Using either a probability or a statistical mechanical approach, the same ratios are obtained. The proximity effect factor is found to be about $\text{55}\text{n}{}_{\mathrm{n}}$ per reacting pair of molecules which show no net attraction or repulsion. The use of translational entropy without inclusion of a rotational entropy term gives a misleading value for this proximity factor. The calculations support the argument that orientation factors can play a large role in the catalytic power of enzymes.