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PubMed2025

Dissecting Sex-Specific Pathology in K18-hACE2 Transgenic Mice Infected With Different SARS-CoV-2 Variants.

Sex-biased differences in COVID-19 outcomes in relation to individual SARS-CoV-2 variants are not well understood. In this study, lungs and nasal cavities of age-matched female and male K18-hACE2 transgenic mice were collected for dissecting sex-specific differences in pathology after infection of SARS-CoV-2 614 G, Delta, or Omicron variant. Overall, Delta infection induced the most severe inflammation and pathology in nasal cavity and lung followed by the 614 G, then Omicron variant. Sex differences in host responses to SARS-CoV-2 infection were variant-specific. Delta-infected males showed increased pulmonary infiltration of CD163+ "M2" macrophages, Ly6G+ neutrophils, and NKR-P1C + NK cells during early onset of infection, and elevated lung inflammatory cytokines such as IL-10, IL-6, and IP-10 than Delta-infected females. Conversely, females had increased lung CD4 + T cell recruitment after Omicron infection and significantly elevated lung MCP-1 secretion after Delta infection than males. Lung spatial transcriptomics data revealed that Delta-infected females had enriched gene pathways related to humoral immune response and interferon signaling, while males had enriched pathways associated with extracellular matrix production, chemokine signaling, and cell chemotaxis. Taken together, this study highlights the complex infection dynamics with respect to individual SARS-CoV-2 variants and underscores the importance of sex as a confounding factor for COVID-19 pathology.

Animals↗
PubMed1999

New pathways in folding of the Tetrahymena group I RNA enzyme.

Previous studies have shown that the earliest detectable step in folding of the Tetrahymena ribozyme is tertiary structure formation of the peripheral element P5abc. This, along with other results, has suggested that P5abc may serve as a scaffold upon which additional tertiary structure is built. Herein we use the onset of oligonucleotide cleavage activity as a readout for native state formation and investigate the effect of P5abc on the rate of folding to the native structure. Despite the early folding of P5abc, its removal to give the E delta P5abc variant decreases the rate of attainment of an active structure less than fivefold (20-100 mM Mg2+, 15-50 degrees C). Furthermore, P5abc added in trans is able to bind the folded E delta P5abc ribozyme and promote oligonucleotide cleavage at least tenfold more rapidly than folding of the wild-type ribozyme, indicating that E delta P5abc does not have to first unfold before productively binding P5abc to form the true native state. This suggests that a state with the overall tertiary structure formed but with P5abc unfolded represents a viable on-pathway intermediate for the wild-type ribozyme. These results provide strong evidence for the existence of two pathways to the native state: in one pathway P5abc forms tertiary structure first, and in another it forms late. The pathway in which P5abc forms first is favored because P5abc can fold quickly and because its tertiary structure is stable in the absence of additional structured elements, not because P5abc formation is required for subsequent folding steps. In the course of these experiments, we also found that most of the ribozyme population does not reach the native state directly under standard conditions in vitro, but instead forms an inactive structure that is stable for hours. Finally, the fraction that does fold to the native state folds with a single rate constant of 1 min-1, suggesting that there are no significantly populated "fast-track" pathways that reach the native state directly by avoiding slow folding steps.

Animals↗
PubMedDate not supplied

Genetics of alcohol dehydrogenase and aldehyde dehydrogenase from Monodelphis domestica cornea: further evidence for identity of corneal aldehyde dehydrogenase with a major soluble protein.

A didelphid marsupial, the gray short-tailed opossum (Monodelphis domestica), was used as a model species to study the biochemical genetics of alcohol dehydrogenases (ADHs) and aldehyde dehydrogenase (ALDH) in corneal tissue. Isoelectric point variants of corneal ALDH (designated ALDH3) and a major soluble protein in corneal extracts were observed among eight families of animals used in studying the genetics of these proteins. Both phenotypes exhibited identical patterns following PAGE-IEF and were inherited in a normal Mendelian fashion, with two alleles at a single locus (ALDH3) showing codominant expression. The data provided evidence for genetic identity of corneal ALDH with this major soluble protein, and supported biochemical evidence, recently reported for purified bovine corneal ALDH, that this enzyme constitutes a major portion of soluble corneal protein (Abedinia et al. 1990). Isoelectric point variants for corneal ADH were also observed, with patterns for the two major forms (ADH3 and ADH4) and one minor form (ADH5) being consistent with the presence of two ADH subunits (designated gamma and delta), and variant phenotypes existing for the gamma subunit. The genetics of this enzyme was studied in the eight families, and the results were consistent with codominant expression of two alleles at a single locus (designated ADH3). It is relevant that a major detoxification function has been proposed for corneal ADH and ALDH, in the oxidoreduction of peroxidic aldehydes induced by available oxygen and UV-B light (Holmes & VandeBerg, 1986a). In addition, a direct role for corneal ALDH as a UV-B photoreceptor in this anterior eye tissue has also been proposed (Abedinia et al. 1990).

Alcohol Dehydrogenase↗
PubMed1997

Molecular model of an alternative splice variant of human IL-4, IL-4 delta 2, a naturally occurring inhibitor of IL-4-stimulated T cell proliferation.

The molecular model of IL-4 delta 2, a naturally occurring splice variant of human IL-4 with exons 1, 3, and 4 in an open reading frame, is described. The second exon codes the main part of the long loop AB connected the helices A and B in parallel superposition. Therefore the hydrophobic core and the native fold of the rest part of IL-4 delta 2 molecule could be preserved without any significant changes only in the case of revolution of the helix A relative to other helices. In the result, the dominated a left-handed four-helix bundle structure of IL-4 with an up-up-down-down structural pattern is transformed to the IL-4 delta 2 structure with a down-up-down-down structural pattern.

Humans↗
PubMed2003

Chronic hepatitis delta virus infection with genotype IIb variant is correlated with progressive liver disease.

We determined the sequence of the hepatitis delta virus (HDV) genome in 40 Japanese patients, most of whom were from the Miyako Islands, Okinawa, Japan. Consensus sequences from 33 HDV full genomes out of a total of 40 patients were determined by directly sequencing four partially overlapping PCR products. Phylogenetic tree analysis classified these 33 complete HDV genomes as HDV genotype I (two patients), genotype IIa (one patient) and genotype IIb (30 patients). Among the 30 genotype IIb patients, there were two clusters of genetic variants. One group consisted of six isolates showing significant homology with genotype IIb, previously reported from Taiwan. The other group consisted of 24 isolates, whose sequences formed a new genetic subgroup (genotype IIb-Miyako; IIb-M). When the genetic structures were compared in detail between IIb and IIb-M, characteristic variations were found in the C-terminal sequence of the large delta antigen-conferring packaging signal as well as the RNA editing site. Determination of subclasses of genotype IIb in a total of 37 patients, including seven HDV patients whose partial HDV sequence was determined, revealed eight patients with IIb and 29 patients with IIb-M. Although there was no significant difference in the clinical background or virological state of hepatitis B virus between these two groups, patients with genotype IIb-M showed greater progression of chronic hepatitis and cirrhosis than those with genotype IIb (P=0.0009). These data indicate the existence of a genetic subgroup of HDV genotype IIb, which is associated with different clinical characteristics and which could be related to genetic variations in functionally important parts of the HDV genome.

Adult↗
PubMed2002

Function of the exon 7 deletion variant estrogen receptor alpha protein in an estradiol-resistant, tamoxifen-sensitive human endometrial adenocarcinoma grown in nude mice.

BACKGROUND: In addition to hormone and DNA binding, interactions, including competition with other proteins, appear to be a critical component of transcriptional regulation by the estrogen receptor alpha (ER(alpha)). In vitro studies suggest that exon deletion (Delta exon) variant forms of ER(alpha) may also play an important role in determining the progression from hormone dependence to hormone independence in receptor positive tumors. METHODS: We investigated the presence of ERalpha mRNA and protein variants and their possible role in a moderately differentiated human endometrial adenocarcinoma grown in nude mice. In addition to wild-type (wt), RT-PCR assay of the tumor revealed the presence of two mRNA variants, a low concentration of Delta5 and a high concentration of Delta7 ER(alpha). We detected wt, Delta7, and Delta5,7 mRNA by sequencing the transcripts after stable transfection of three HeLa cells with either splice variant. The linked in vitro translation/transcription assay of the transfected cells and the Western blot analysis of the original tumor generated both wt (66 kDa) and Delta7 (52 kDa), Delta5,7 (46 kDa) ER(alpha) proteins. RESULTS: Tumor growth was characterized as estradiol and progesterone resistant but tamoxifen sensitive, i.e., neither estradiol nor progesterone treatment altered the growth rate, whereas tamoxifen treatment significantly increased the tumor volume doubling time. Estradiol treatment decreased the wt and increased the Delta7 variant ER(alpha) protein expression significantly in a dose-dependent manner. Tamoxifen treatment, however, increased the expression of both proteins whereas progesterone had no effect. Estradiol treatment did not influence expression of the Delta5,7 variant protein, which increased significantly in the tamoxifen-treated tumors. Gel mobility shift assays revealed that both wt and Delta7 ER(alpha) proteins bind to the consensus DNA sequence, whereas the Delta5,7 variant protein did not. CONCLUSIONS: We conclude that estradiol, tamoxifen, and progesterone regulate wt and variant ER(alpha) mRNA and protein expression separately and differently and that this hormonal regulation probably occurs, via different mechanisms, at the transcriptional or posttranscriptional level. The Delta7 variant ER(alpha) may play a crucial role in the determination of hormone sensitivity and thus in the outcome of hormone treatment of human endometrial adenocarcinomas.

Adenocarcinoma↗
PubMed2002

p53 induces the expression of its antagonist p73 Delta N, establishing an autoregulatory feedback loop.

The p53 tumor suppressor protein activates transcription and induces cell death. A close homologue of p53, termed p73, is expressed in transactivating (TA) forms that induce growth arrest and apoptosis much like p53. However, the p73 gene contains a second promoter, giving rise to the expression of p73 Delta N, a species of p73 proteins that lack the N-terminal transactivation domain. We show here that the expression of p73 Delta N is induced by p53 on the mRNA and protein level. The promoter that regulates p73 Delta N expression in human cells was cloned and found to be activated by p53, as well as by p73TA, directly through a specific DNA element. The p73 Delta N proteins, that are thereby expressed, bound to p53-responsive promoter DNA, competed with p53 for DNA binding, antagonized the activation of transcription by p53, and prevented p53-induced cell death. In addition, a transcriptional repressor domain was identified within the splicing variant p73 Delta Nalpha. The combination of p73DeltaNalpha and mdm2 antagonized p53 more strongly than either p73Nalpha or mdm2 alone. Blocking endogenous p73 Delta N by a trans dominant fragment, or its removal by siRNA, increased the activity of a p53-responsive promoter in cells that contain a wild type p53 gene. Thus, the induction of p73 Delta N expression by p53 establishes an autoregulatory feedback loop that keeps the trigger of cell death under tight control.

Apoptosis↗
PubMed1983

A new high-performance liquid chromatographic procedure for the separation and quantitation of various hemoglobin variants in adults and newborn babies.

A new cation-exchange HPLC method is described for the separation and quantitation of abnormal human Hbs. The method makes use of Synchropak CM 300, a silica support with carboxylic acid residues, and Bis-Tris-KCN-Na-acetate developers and allows a completion of the chromatogram in 50 to 90 min depending on the sample to be analyzed. Specific chromatographic profiles have been obtained for several beta, alpha, and delta chain variants. The method is useful not only for the quantitation of Hb F and Hb A2 (except in the presence of Hb E) but also provides easy differentiation between simple heterozygotes for a specific abnormality and persons with the same abnormality together with an additional beta-thalassemia heterozygosity. Probably the most important application of the new procedure is in the quantitation of Hb A and the beta chain variants S, C, O-Arab, and E in cord blood samples, thus facilitating the diagnosis of conditions such as AE, EE, AS, SS, S-beta +thal, AC, CC, C-beta +thal, SC, and SO in newborn babies.

Adult↗
PubMed1994

Chemical probing studies of variants of the genomic hepatitis delta virus ribozyme by primer extension analysis.

We have investigated in detail the higher order structure of the genomic hepatitis delta virus (HDV) ribozyme using various base-specific chemical probes under native, semi-denaturing, and denaturing conditions. The bases of the HDV ribozyme were probed by treatment with dimethyl sulfate [which reacts with A (at N1) and C (at N3)] and a carbodiimide [which reacts with U (at N3) and G (at N1)]. In addition, for probing G residues (at N7), RNA samples were treated with NaBH4 and aniline after modification by treatment with dimethyl sulfate. The sites of modified positions were identified by primer extension analysis with reverse transcriptase. In general, our results are consistent with the proposed pseudoknot model of secondary structure, a model that is based on data from ribonucleolytic cleavage experiments. Our results provide clues to the identification of interacting bases in the HDV ribozyme. Furthermore, using this method we identified local conformational changes in several stem variants.

Aniline Compounds↗
PubMed1975

Thalassaemia in northern Liberia. A survey in the Mount Nimba area.

A population survey in northern Liberia showed an average incidence of 9 percent of beta-thalassaemia trait. There was considerable tribal variation, the highest rates being mainly found in tribes having a low incidence of Hb S. A single example of deltabeta-thalassaemia trait was also found; the incidence of delta-chain variants was 1.8 percent. The effect of malaria on Hb A2 levels was investigated but appeared to be negligible. The problems of beta-thalassaemia and Hb S occurring in the same population are discussed. It is considered that, although made on a local sample, the results of this survey indicate a high incidence of beta-thalassaemia trait elsewhere in Liberia and that this is a suitable are for investigations of linkage at beta- and delta-chain loci. No conclusion is at present possible from the data on the presence of alpha-thalassaemia although 10 percent of neonates were found to have increased levels of Hb Barts.

Adolescent↗
PubMed1994

Distinct functions of capsid protein in assembly and movement of tobacco etch potyvirus in plants.

Tobacco etch potyvirus engineered to express the reporter protein beta-glucuronidase (TEV-GUS) was used for direct observation and quantitation of virus translocation in plants. Four TEV-GUS mutants were generated containing capsid proteins (CPs) with single amino acid substitutions (R154D and D198R), a double substitution (DR), or a deletion of part of the N-terminal domain (delta N). Each modified virus replicated as well as the parental virus in protoplasts, but was defective in cell-to-cell movement through inoculated leaves. The R154D, D198R and DR mutants were restricted essentially to single, initially infected cells. The delta N variant exhibited slow cell-to-cell movement in inoculated leaves, but was unable to move systemically due to a lack of entry into or replication in vascular-associated cells. Both cell-to-cell and systemic movement defects of each mutant were rescued in transgenic plants expressing wild-type TEV CP. Cell-to-cell movement, but not systemic movement, of the DR mutant was rescued partially in transgenic plants expressing TEV CP lacking the C-terminal domain, and in plants expressing CP from the heterologous potyvirus, potato virus Y. Despite comparable levels of accumulation of parental virus and each mutant in symptomatic tissue of TEV CP-expressing transgenic plants, virions were detected only in parental virus- and delta N mutant-infected plants, as revealed using three independent assays. These data suggest that the potyvirus CP possesses distinct, separable activities required for virion assembly, cell-to-cell movement and long-distance transport.

Amino Acid Sequence↗
PubMed1996

[Endocrinological contribution for invasion and metastasis in gynecological cancers].

The development and growth of gynecological cancers are related to steroid hormone actions. Alternatively, this prompts us to study biological contribution of sex steroids for invasion and metastasis in gynecological cancers. The first step of metastasis is the detachment of tumor cells. The adherens junction forms a main cell-to-cell junctional complex, mainly consisting of E-cadherin, alpha- and beta-catenins, etc. Estrogen suppressed the expression of their mRNAs, and the adhesive function of cells via adherens junction in endometrial cancer cells. Progestin and danazol reversed the estrogen-induced suppression. Estrogen enhanced invasiveness of endometrial cancer cells though the reconstituted basement membrane and interstitium using the Boyden chamber. Progestin reduced the estrogen-induced invasiveness. The final step of metastasis is tumor-derived neovascularization for growth of metastatic cancer cells. Progestin inhibited basic fibroblast growth factor (FGF) activity, which mainly contribute to tumor-derived neovascularization, regardless of growth-inhibition in some endometrial cancers. Progestin inhibits basic FGF in well-differentiated (WD) endometrial cancer cells, but not in poorly differentiated (PD) endometrial cancer cells. TNP470, a inhibitor of vessel endothelial proliferation, inhibited directly basic FGF in the PD. Therefore, the adequate combination therapy of progestin and TNP470 could efficiently inhibit angiogenic potential of heterologous endometrial cancers. The ratio of estrogen receptor exon 5 splicing variant (ER delta E5) to wild type-ER mRNA expression increased in some metastatic lesions of cancers. The dominant expression of ER delta E5 mRNA might be related to metastatic potential of gynecological cancers. Progesterone receptor from A (PR-A), initiated from in-frame AUG present in the PR from B (PR-B) mRNA, lacks the N-terminal 164 amino acids of PR-B, and acts as a progestin-dependent, trans-dominant repressor of PR-B function and other steroid receptor function. The expression of PR-B mRNA was dominantly expressed in all metastatic gynecological cancers given. This might be related to metastatic potential of gynecological cancers. To know tumorigenic potential of sex steroid receptors, ER, PR-A and PR-B genes were transfected to NIH3T3 cells. Transfected cells with PR-A gene alone formed a few colonies in double soft agar. On the other hand, the cells with PR-B and ER genes under the presence of estradiol formed plenty of colonies. Therefore, overexpression of PR-B under the absence of PR-A might be related to tumorigenic potential. In conclusion, estrogen could enhance some steps of metastasis in endometrial cancers, and progestin could inhibit the estrogen-induced events, regardless of growth-inhibition. Relative over-expression of ER exon 5 splicing variant, and PR-B might contribute to metastatic potential in gynecological cancers.

Estrogens↗
PubMed1991

The B cell antigen receptor of class IgD can be expressed on the cell surface in two different forms.

Membrane-bound immunoglobulins of the IgM and IgD class are expressed on the B cell surface in association with a disulfide-linked heterodimer consisting of alpha and beta subunits. While the alpha component of the IgM antigen receptor (IgM-alpha, 34 kDa) is encoded by the B cell-specific gene mb-1, the gene coding for IgD-alpha (35 kDa) has not yet been identified. We show here that the alpha component of the IgD antigen receptor is also encoded by the mb-1 gene. The difference in molecular weight between IgM-alpha and IgD-alpha thus seems to be due to post-translational modifications of the mb-1 gene product. We also demonstrate that the previously described myeloma variant J558L delta m2.6 expresses an alternative form of the IgD antigen receptor, which does not contain an alpha/beta heterodimer.

Animals↗
PubMed1997

Construction and overexpression of a synthetic gene for human DNA methylguanine methyltransferase: renaturation and rapid purification of the protein.

A synthetic gene was constructed that encodes human DNA methylguanine methyltransferase (hMGMT). The synthetic gene was designed with a number of unique restriction sites to facilitate cassette mutagenesis and to reflect the preferences found among genes in Escherichia coli. Both the full-length gene and a gene for a functional variant (hMGMT delta C) that lacks the C-terminal 28 codons were constructed, and the genes were overexpressed using a T7 RNA polymerase promoter. The proteins are made in the form of insoluble aggregates but the truncated form of the protein (hMGMT delta C) has been successfully denatured, renatured, and purified to near homogeneity by ion exchange. Methyltransferase activity assays of hMGMT delta C demonstrate that the reconstituted protein has substantial DNA repair activity, though somewhat less than full-length hMGMT that had been expressed and purified in a soluble form. Mass spectrometry of a mixture of proteolytic fragments confirmed the protein sequence and indicated no detectable oxidation of the active site cysteine. The protein was determined to be monomeric by gel filtration chromatography, and circular dichroism spectra for renatured hMGMT delta C and fully soluble hMGMT are consistent with the renatured protein preparation being fully folded. Refolded hMGMT delta C had a curious propensity to form large aggregates in a time-dependent manner when injected into a dynamic light scattering instrument; this aggregation behavior was not observed for hMGMT purified in a soluble form. Differences in susceptibility to aggregation may account for differences in methyltransfer activity. Yields of purified protein were approximately 5 mg/liter of culture.

Amino Acid Sequence↗
PubMed1989

Activation of the lac promoter and its variants. Synergistic effects of catabolite activator protein and supercoiling in vitro.

Escherichia coli lac promoter variants are shown to be subject to large synergistic transcriptional activation by catabolite activator protein (CRP) and DNA supercoiling in vitro. Activation was studied for the lac wild-type promoter, a promoter with a variant spacing (lac delta l) and two promoters with variant -10 regions (lac ps, lac UV5). The variant promoters respond to the simultaneous presence of CRP and supercoiling by exhibiting large multiplicative activation at the low to moderate superhelicities that are most pertinent in vivo. Although all four promoters can be activated by CRP, those made stronger by changing downstream promoter elements are less CRP-activated even though each contains an identical CRP binding site. When each of the variant promoters is made stronger by introducing DNA supercoils, the apparent CRP activation initially remains constant but eventually declines at higher superhelicities. Thus, strengthening the lac promoter through either DNA sequence changes or the introduction of high-level DNA supercoiling can lead to diminished potential for activation by CRP. These results are interpreted in terms of a role for CRP in providing extra stabilizing contacts for RNA polymerase binding that are necessary only when other stabilizing features of promoter structure are lacking.

Bacterial Proteins↗
PubMed2025

Vaccine efficacy of NVX-CoV2373 against SARS-CoV-2 infection in adolescents in the USA: an ancillary study to a phase 3, observer-blinded, randomised, placebo-controlled trial.

BACKGROUND: Although existing COVID-19 vaccines are known to be highly effective against severe disease and death, data are needed to assess their ability to reduce SARS-CoV-2 infection. We aimed to estimate the efficacy of the NVX-CoV2373 protein subunit vaccine against SARS-CoV-2 infection, regardless of symptoms, among adolescents. METHODS: We performed an ancillary observational study (SNIFF) to the phase 3, observer-blinded, randomised, placebo-controlled PREVENT-19 trial that assessed vaccine efficacy against symptomatic COVID-19 in the USA. Participants in the PREVENT-19 trial included healthy adolescents aged 12-17 years and with no history of laboratory-confirmed SARS-CoV-2 infection. They were randomly assigned (2:1) to receive either the NVX-CoV2373 (Novavax, Gaithersburg, MD, USA) vaccine (immediate NVX-CoV2373 group) or placebo (delayed NVX-CoV2373 group) on days 0 and 21 (initial series). After 2 months, in a crossover series, participants received two doses, 21 days apart, of the intervention that they did not receive in their initial series. Participants at 47 of the PREVENT-19 sites were invited to participate in the SNIFF study and self-collect nasal swabs at home twice weekly for SARS-CoV-2 testing to assess vaccine efficacy against SARS-CoV-2 infection. This primary outcome was defined as the first identification of SARS-CoV-2 detected by RT-PCR, regardless of symptoms, with onset within 4 weeks after the second dose of the initial vaccination series until the second dose of the crossover series. Secondary outcomes were vaccine efficacy against asymptomatic and minimally symptomatic SARS-CoV-2 infection, durability of vaccine efficacy against SARS-CoV-2 infection, and durability of vaccine efficacy against asymptomatic and minimally symptomatic infections. Outcomes were analysed in the modified intention-to-treat population, which included all participants without previous SARS-CoV-2 infection and was restricted to participants enrolled within 4 weeks of the second dose of the primary (primary analysis population) or crossover (post-crossover analysis population) series. This study is registered with ClinicalTrials.gov (NCT04611802). FINDINGS: Between June 1 and Dec 17, 2021, 1196 (53·2%) of the 2247 adolescent participants recruited in the PREVENT-19 trial enrolled in the SNIFF study. The primary analysis population included 471 participants in the immediate NVX-CoV2373 group and 220 in the delayed NVX-CoV2373 group. Incidence of SARS-CoV-2 infection was 14·9 cases per 100 person-years (95% CI 7·9-25·5) in the immediate group and 54·2 cases per 100 person-years (33·6-82·9) in the delayed group; vaccine efficacy was 73·5% (95% CI 47·1-86·7; p=0·0002). Incidence of minimally symptomatic or asymptomatic SARS-CoV-2 infection was 10·3 cases per 100 person-years (95% CI 4·7-19·6) in the immediate group and 36·1 cases per 100 person-years (19·8-60·7) in the delayed group; vaccine efficacy was 72·8% (95% CI 37·1-88·2; p=0·0023). After the second crossover dose, incidence of SARS-CoV-2 was 14·6 cases per 100 person-years (95% CI 8·6-23·0) in the immediate group (receiving placebo at crossover) and 9·1 cases per 100 person-years (3·0-21·3) in the delayed group, with a durability ratio of 160·3 (95% CI 59·5-431·6; p=0·35). Almost all infections after crossover were minimally symptomatic or asymptomatic, with a durability ratio of 151·4 (55·9-410·4; p=0·41). INTERPRETATION: Among adolescents participating in the PREVENT-19 trial during the delta (B.1.617.2) variant wave of the COVID-19 pandemic, the NVX-CoV2373 vaccine was highly efficacious against SARS-CoV-2 infection regardless of symptoms, indicating its potential to reduce the reservoir of infections that contribute to community transmission. FUNDING: US Department of Health and Human Services, Administration for Strategic Preparedness and Response, Biomedical Advanced Research and Development Authority, National Institute of Allergy and Infectious Diseases, and National Institutes of Health.

Adolescent↗
PubMed2004

Conserved "PAL" sequence in presenilins is essential for gamma-secretase activity, but not required for formation or stabilization of gamma-secretase complexes.

Generation of A beta from the beta-amyloid precursor protein (APP) requires a series of proteolytic processes, including an intramembranous cleavage catalyzed by an aspartyl protease, gamma-secretase. Two aspartates in presenilins (PS) are required for gamma-secretase activity (D257 and D385 of PS1), suggesting that PS may be part of this protease. Little is known concerning the importance of other sequences in PS for activity. We introduced point mutations (P433L, A434D, L435R) into a completely conserved region C-terminal to transmembrane domain eight of PS1. The P433L mutation abolished PS1 endoproteolysis as well as gamma-secretase cleavage of APP and Notch in PS1/2 K/O cells. In HEK cells, expression of PS1/P433L reduced A beta production and caused accumulation of APP C-terminal stubs. When the P433L mutation was introduced into the non-cleavable Delta exon 9 (Delta E9) variant of PS1, it abolished gamma-secretase cleavage of APP and Notch. The P433L holoprotein is stable and incorporated into the high molecular weight gamma-secretase complex, arguing that P433 is not necessary for formation or stabilization of the gamma-secretase complex. Other non-conservative mutations in the invariant P(433)A(434)L(435) sequence also result in a phenotype that is indistinguishable from the aspartate mutants, suggesting a direct involvement of this sequence in gamma-secretase activity.

Amino Acid Sequence↗
PubMed2003

The role of Staphylococcus aureus sortase A and sortase B in murine arthritis.

Gram-positive pathogenic bacteria display proteins on their surface that play important roles during infection. In Staphylococcus aureus, these surface proteins are anchored to the cell wall by two sortase enzymes, SrtA and SrtB, that recognize specific surface protein sorting signals. The role of sortase enzymes in bacterial virulence was examined using a murine septic arthritis model. Intravenous inoculation with any of the Delta(srtA), Delta(srtB) or Delta(srtAB) mutants resulted in significantly increased survival and significantly lower weight loss compared with the parental strain. Mice inoculated with the Delta(srtA) mutant did not express severe arthritis, while arthritis in mice inoculated with the Delta(srtB) mutant was not different from that seen in mice that were infected with the wild-type parent strain. Furthermore, persistence of staphylococci in kidneys and joints following intravenous inoculation of mice was more pronounced for wild-type and Delta(srtB) mutant strains than for Delta(srtA) or Delta(srtAB) variants. Together these results indicate that sortase B (srtB) plays a contributing role during the pathogenesis of staphylococcal infections, whereas sortase A (srtA) is an essential virulence factor for the establishment of septic arthritis.

Aminoacyltransferases↗