Characterization of a broadly reactive monoclonal antibody against norovirus genogroups I and II: recognition of a novel conformational epitope

Norovirus, which belongs to the family Caliciviridae, is one of the major causes of nonbacterial acute gastroenteritis in the world. The main human noroviruses are of genogroup I (GI) and genogroup II (GII), which were subdivided further into at least 15 and 18 genotypes (GI/1 to GI/15 and GII/1 to GII/18), respectively. The development of immunological diagnosis for norovirus had been hindered by the antigen specificity of the polyclonal antibody. Therefore, several laboratories have produced broadly reactive monoclonal antibodies, which recognize the linear GI and GII cross-reactive epitopes or the conformational GI-specific epitope. In this study, we characterized the novel monoclonal antibody 14-1 (MAb14-1) for further development of the rapid immunochromatography test. Our results demonstrated that MAb14-1 could recognize 15 recombinant virus-like particles (GI/1, 4, 8, and 11 and GII/1 to 7 and 12 to 15) and showed weak affinity to the virus-like particle of GI/3. This recognition range is the broadest of the existing monoclonal antibodies. The epitope for MAb14-1 was identified by fragment, sequence, structural, and mutational analyses. Both terminal antigenic regions (amino acid positions 418 to 426 and 526 to 534) on the C-terminal P1 domain formed the conformational epitope and were in the proximity of the insertion region (positions 427 to 525). These regions contained six amino acids responsible for antigenicity that were conserved among genogroup(s), genus, and Caliciviridae. This epitope mapping explained the broad reactivity and different titers among GI and GII. To our knowledge, we are the first group to identify the GI and GII cross-reactive monoclonal antibody, which recognizes the novel conformational epitope. From these data, MAb14-1 could be used further to develop immunochromatography.     

Acceleration of R5 HIV replication by polymorphonuclear neutrophils in cultures of macrophages

Cell-to-cell contact between monocyte-derived macrophages (MDM) and endothelial cells has resulted in the increased proliferation of CC chemokine receptor 5/M-tropic (R5) human immunodeficiency virus (HIV) in MDM. In the present study, R5 HIV replication was shown to be increased by polymorphonuclear neutrophils (PMN) in MDM cultures through the soluble factors released from these PMN. The replication of R5 HIV in MDM was greatly enhanced when PMN were added to cultures. An increase in the replication of R5 HIV was also demonstrated when the virus was replicated in MDM cultured in a double chamber transwell with PMN. Chemokine ligand (CCL) 2 and interleukin (IL)-10 were detected in culture fluids of PMN exposed to R5 HIV. The replication of R5 HIV was not accelerated in cultures of MDM and PMN in a double chamber transwell supplemented with a mixture of monoclonal antibodies directed against CCL2 and IL-10. Similarly, the replication of R5 HIV was accelerated in MDM cultures supplemented with a mixture of recombinant CCL2 and IL-10. These results indicated that, in response to the viral stimulation, PMN produce CCL2 and IL-10 and enhance the replication of R5 HIV in MDM cultures.     

Anti-peptide antibody production elicited by in vitro immunization of human peripheral blood mononuclear cells

Human monoclonal antibodies have great potential for use in the treatment of various diseases. We have established an in vitro immunization protocol for inducing antigen-specific antibody production from human peripheral blood mononuclear cells (PBMCs). In the in vitro immunization protocol, PBMCs are pretreated with L-leucyl-L-leucine methyl ester (LLME) to remove suppressive cells, and are sensitized and cultured with a soluble antigen in the presence of IL-2, IL-4 and muramyl dipeptide for 8 d, and then an antigen-specific antibody is produced. In this study, we examined the novel possibility of an in vitro immunization protocol, specifically, whether LLME-treated PBMCs can be sensitized with a peptide antigen to produce an anti-peptide antibody. The results indicate that antigen-specific immune responses were elicited by a peptide antigen derived from rice allergen, a cholera toxin B subunit, and TNF-alpha as a sensitizing antigen in in vitro immunization. These results suggest that the in vitro immunization protocol is applicable in the generation of an anti-peptide antibody against various antigens, including food allergens, foreign antigens, and self-antigens.     

Recent advances in the generation of human monoclonal antibody

The use of monoclonal antibodies (mAbs) has now gained a niche as an epochal breakthrough in medicine. Engineered antibodies (Abs) currently account for over 30% of biopharmaceuticals in clinical trials. Several methods to generate human mAbs have evolved, such as (1) immortalization of antigen-specific human B cell hybridoma technology, (2) generation of chimeric and humanized antibody (Ab) from mouse Ab by genetic engineering, (3) acquisition of antigen-specific human B cells by the phage display method, and (4) development of transgenic mice for producing human mAbs. Besides these technologies, we have independently developed a method to generate human mAbs by combining the method of in vitro immunization using peripheral blood mononuclear cells and the phage display method. In this paper, we review the developments in these technologies for generating human mAbs.     

Clinical application of Clostridium botulinum type A neurotoxin purified by a simple procedure for patients with urinary incontinence caused by refractory destrusor overactivity

Type A neurotoxin of Clostridium botulinum was purified by a simple procedure using a lactose gel column. This procedure was previously reported for type B neurotoxin. Hemagglutinin-positive toxins (19S and 16S) were bound to the column under acid conditions, and the neurotoxin alone was dissociated from these hemagglutinin-positive toxins by changing the pH of the column to an alkaline condition. The toxicity of this purified toxin preparation was retained for at least 1 year at -30 degrees C by supplementing it with either 0.1% albumin or 0.05% albumin plus 1% trehalose. This preparation was used to treat 18 patients with urinary incontinence caused by refractory idiopathic and neurogenic detrusor overactivity; 16 of the patients showed excellent improvement. Improvements started within 1 week after injection in most cases and lasted 3-12 months [corrected]     

Synthesis and evaluation of novel pyrimidine-based dual EGFR/Her-2 inhibitors

A structure-activity relationship study of 4-anilinopyrimidines for dual EGFR/Her-2 inhibitor has resulted in the identification of 4-anilino-5-alkenyl or 5-alkynyl-6-methylpyrimidine derivatives that have exhibited effective inhibitory activity against both enzymes. The presence of 5-alkenyl or 5-alkynyl moiety bearing terminal hydrophilic group played important role for inhibition of these enzymes. Selected compounds in the series demonstrated some activity against Her-2 dependent cell line (BT474).     

A LC-MS/MS method for the specific, sensitive, and simultaneous quantification of 5-aminolevulinic acid and porphobilinogen

Accurate determinations of 5-aminolevulinic acid (ALA) and porphobilinogen (PBG) in physiologic fluids are required for the diagnosis and therapeutic monitoring of acute porphyrias. Current colorimetric methods are insensitive and over-estimate ALA and PBG due to poor specificity, while LC-MS/MS methods increase sensitivity, but have limited matrices. An LC-MS/MS method was developed to simultaneously determine ALA and PBG concentrations in fluids or tissues which were solid phase extracted, butanol derivatized, and quantitated by selective reaction monitoring using (13)C(5), (15)N-ALA and 2,4-(13)C(2)-PBG internal standards. ALA was separated from interfering compounds on a reverse phase C8-column. For ALA and PBG, the matrix effects (87.3-105%) and process efficiencies (77.6-97.8% and 37.2-41.6%, respectively) were acceptable in plasma and urine matrices. The assay was highly sensitive for ALA and PBG (LLOQ=0.05 μM with 25 μL urine or 100 μL plasma), and required ～4 h from extraction to results. ALA and PBG accuracy ranged from 88.2 to 110% (n=10); intra- and inter-assay coefficients of variations were <10% for urine and plasma. In clinical applications, patients with mutation-confirmed acute porphyrias had normal to slightly increased urinary ALA and PBG levels when asymptomatic, and high levels during acute attacks, which decreased with hemin therapy. In AIP mice, baseline ALA and PBG levels in urine, plasma, and liver were increased after phenobarbital induction 28-/63-, 42-/266-, and 13-/316-fold, respectively. This LC-MS/MS method is rapid, specific, highly sensitive, accurate, and simultaneously measures ALA and PBG in urine, plasma, and tissues permitting porphyria clinical diagnoses, therapeutic monitoring, and research.     

Structural and functional evolution of three cardiac natriuretic peptides

Natriuretic peptides (NPs) are a group of hormones playing important roles in cardiovascular and osmoregulatory systems in vertebrates. Among the NP subtypes, atrial NP (ANP), B-type NP (BNP), and ventricular NP (VNP) are circulating hormones expressed exclusively in the heart (cardiac NPs). The constitution of cardiac NPs is variable among species of vertebrates. In order to understand the evolutionary and functional significance of such variation, we performed a systematic survey of cardiac NP cDNAs in nine taxonomically diverse teleosts inhabiting environments of varying salinity. The discovery of the coexistence of the ANP, BNP, and VNP genes in the eel and rainbow trout suggested that the ancestral teleost had all three cardiac NPs. As the VNP cDNA was undetectable in ayu and six species of Neoteleostei, it is possible that VNP was lost before the divergence of Osmeroidei. The ANP gene was also undetectable in the medaka. Thus, only the BNP gene is universal in species examined in the present study. Synthetic medaka BNP preferentially activated two medaka GC-A-type receptors, suggesting that the three cardiac NPs share the same receptor. However, the regulation of BNP expression may be the most strict because ATTTA repeats in the 3'-untranslated region and the dibasic motif in the ring are conserved among teleosts and tetrapods. Linkage analyses in the rainbow trout located ANP, BNP, and VNP genes on the same chromosome, which suggested the generation of the VNP gene by tandem duplication as observed with ANP and BNP genes. If the duplication occurred before the divergence of tetrapods and teleosts, VNP may exist in the tetrapod lineage.