RESUMEN
There is still no safe and effective vaccine against dengue virus infection. Epidemics of dengue virus infection are increasingly a threat to human health around the world. Antibodies generated in response to dengue infection have been shown to impact disease development and effectiveness of dengue vaccine. In this study, we investigated monoclonal antibody responses to an experimental dengue vaccine in rhesus macaques. Variable regions of both heavy chain (VH) and light chain (VL) were cloned from single antibody-secreting B cells. A total of 780 monoclonal antibodies (mAbs) composed of paired VH and VL were characterized. Results show that the vaccination induces mAbs with diverse germline sequences and a wide range of binding affinities. Six potent neutralizing mAbs were identified among 130 dengue envelope protein binders. Critical amino acids for each neutralizing antibody binding to the dengue envelope protein were identified by alanine scanning of mutant libraries. Diverse epitopes were identified, including epitopes on the lateral ridge of DIII, the I-III hinge, the bc loop adjacent to the fusion loop of DII, and the ß-strands and loops of DI. Significantly, one of the neutralizing mAbs has a previously unknown epitope in DII at the interface of the envelope and membrane protein and is capable of neutralizing all four dengue serotypes. Taken together, the results of this study not only provide preclinical validation for the tested experimental vaccine, but also shed light on a potential application of the rhesus macaque model for better dengue vaccine evaluation and design of vaccines and immunization strategies.
Asunto(s)
Anticuerpos Monoclonales , Anticuerpos Neutralizantes , Anticuerpos Antivirales , Vacunas contra el Dengue , Epítopos , Cadenas Pesadas de Inmunoglobulina , Cadenas Ligeras de Inmunoglobulina , Animales , Anticuerpos Monoclonales/genética , Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/genética , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/genética , Anticuerpos Antivirales/inmunología , Vacunas contra el Dengue/genética , Vacunas contra el Dengue/inmunología , Virus del Dengue/inmunología , Epítopos/genética , Epítopos/inmunología , Cadenas Pesadas de Inmunoglobulina/genética , Cadenas Pesadas de Inmunoglobulina/inmunología , Cadenas Ligeras de Inmunoglobulina/genética , Cadenas Ligeras de Inmunoglobulina/inmunología , Macaca mulattaRESUMEN
A major goal for HIV-1 vaccine development is an ability to elicit strong and durable broadly neutralizing antibody (bNAb) responses. The trimeric envelope glycoprotein (Env) spikes on HIV-1 are known to contain multiple epitopes that are susceptible to bNAbs isolated from infected individuals. Nonetheless, all trimeric and monomeric Env immunogens designed to date have failed to elicit such antibodies. We report the structure-guided design of HIV-1 cyclically permuted gp120 that forms homogeneous, stable trimers, and displays enhanced binding to multiple bNAbs, including VRC01, VRC03, VRC-PG04, PGT128, and the quaternary epitope-specific bNAbs PGT145 and PGDM1400. Constructs that were cyclically permuted in the V1 loop region and contained an N-terminal trimerization domain to stabilize V1V2-mediated quaternary interactions, showed the highest homogeneity and the best antigenic characteristics. In guinea pigs, a DNA prime-protein boost regimen with these new gp120 trimer immunogens elicited potent neutralizing antibody responses against highly sensitive Tier 1A isolates and weaker neutralizing antibody responses with an average titer of about 115 against a panel of heterologous Tier 2 isolates. A modest fraction of the Tier 2 virus neutralizing activity appeared to target the CD4 binding site on gp120. These results suggest that cyclically permuted HIV-1 gp120 trimers represent a viable platform in which further modifications may be made to eventually achieve protective bNAb responses.
Asunto(s)
Anticuerpos Neutralizantes/sangre , Diseño de Fármacos , Anticuerpos Anti-VIH/sangre , Proteína gp120 de Envoltorio del VIH/inmunología , Proteína gp120 de Envoltorio del VIH/metabolismo , Infecciones por VIH/inmunología , VIH-1/inmunología , Animales , Anticuerpos Neutralizantes/inmunología , Sitios de Unión , Cristalografía por Rayos X , Epítopos/inmunología , Cobayas , Anticuerpos Anti-VIH/inmunología , Infecciones por VIH/sangre , Infecciones por VIH/virología , Humanos , Unión Proteica , Conformación Proteica , Multimerización de ProteínaRESUMEN
Human respiratory syncytial virus (RSV) is a common cause of severe respiratory disease among infants, immunocompromised individuals, and the elderly. No licensed vaccine is currently available. In this study, we evaluated two parainfluenza virus 5 (PIV5)-vectored vaccines expressing RSV F (PIV5/F) or G (PIV5/G) protein in the cotton rat and African green monkey models for their replication, immunogenicity, and efficacy of protection against RSV challenge. Following a single intranasal inoculation, both animal species shed the vaccine viruses for a limited time but without noticeable clinical symptoms. In cotton rats, the vaccines elicited RSV F- or G-specific serum antibodies and conferred complete lung protection against RSV challenge at doses as low as 103 PFU. Neither vaccine produced the enhanced lung pathology observed in animals immunized with formalin-inactivated RSV. In African green monkeys, vaccine-induced serum and mucosal antibody responses were readily detected, as well. PIV5/F provided nearly complete protection against RSV infection in the upper and lower respiratory tract at a dose of 106 PFU of vaccine. At the same dose levels, PIV5/G was less efficacious. Both PIV5/F and PIV5/G were also able to boost neutralization titers in RSV-preexposed African green monkeys. Overall, our data indicated that PIV5/F is a promising RSV vaccine candidate.IMPORTANCE A safe and efficacious respiratory syncytial virus (RSV) vaccine remains elusive. We tested the recombinant parainfluenza virus 5 (PIV5) vectors expressing RSV glycoproteins for their immunogenicity and protective efficacy in cotton rats and African green monkeys, which are among the best available animal models to study RSV infection. In both species, a single dose of intranasal immunization with PIV5-vectored vaccines was able to produce systemic and local immunity and to protect animals from RSV challenge. The vaccines could also boost RSV neutralization antibody titers in African green monkeys that had been infected previously. Our data suggest that PIV5-vectored vaccines could potentially protect both the pediatric and elderly populations and support continued development of the vector platform.
Asunto(s)
Virus de la Parainfluenza 5/genética , Infecciones por Virus Sincitial Respiratorio/prevención & control , Vacunas contra Virus Sincitial Respiratorio/inmunología , Virus Sincitial Respiratorio Humano/inmunología , Animales , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Chlorocebus aethiops , Modelos Animales de Enfermedad , Vectores Genéticos , Pulmón/virología , Ratas , Infecciones por Virus Sincitial Respiratorio/inmunología , Infecciones por Virus Sincitial Respiratorio/virología , Vacunas contra Virus Sincitial Respiratorio/administración & dosificación , Vacunas contra Virus Sincitial Respiratorio/genética , Virus Sincitial Respiratorio Humano/genética , Sigmodontinae , Vacunación , Vacunas Sintéticas/administración & dosificación , Vacunas Sintéticas/inmunología , Células Vero , Proteínas del Envoltorio Viral/genética , Proteínas Virales de Fusión/genéticaRESUMEN
A prophylactic vaccine for genital herpes disease remains an elusive goal. We report the results of two studies performed collaboratively in different laboratories that assessed immunogenicity and vaccine efficacy in herpes simplex virus 1 (HSV-1)-seropositive guinea pigs immunized and subsequently challenged intravaginally with HSV-2. In study 1, HSV-2 glycoproteins C (gC2) and D (gD2) were produced in baculovirus and administered intramuscularly as monovalent or bivalent vaccines with CpG and alum. In study 2, gD2 was produced in CHO cells and given intramuscularly with monophosphoryl lipid A (MPL) and alum, or gC2 and gD2 were produced in glycoengineered Pichia pastoris and administered intramuscularly as a bivalent vaccine with Iscomatrix and alum to HSV-1-naive or -seropositive guinea pigs. In both studies, immunization boosted neutralizing antibody responses to HSV-1 and HSV-2. In study 1, immunization with gC2, gD2, or both immunogens significantly reduced the frequency of genital lesions, with the bivalent vaccine showing the greatest protection. In study 2, both vaccines were highly protective against genital disease in naive and HSV-1-seropositive animals. Comparisons between gD2 and gC2/gD2 in study 2 must be interpreted cautiously, because different adjuvants, gD2 doses, and antigen production methods were used; however, significant differences invariably favored the bivalent vaccine. Immunization of naive animals with gC2/gD2 significantly reduced the number of days of vaginal shedding of HSV-2 DNA compared with that for mock-immunized animals. Surprisingly, in both studies, immunization of HSV-1-seropositive animals had little effect on recurrent vaginal shedding of HSV-2 DNA, despite significantly reducing genital disease.
Asunto(s)
Herpes Genital/prevención & control , Herpesvirus Humano 1/inmunología , Proteínas del Envoltorio Viral/inmunología , Vacunas Virales/farmacología , Análisis de Varianza , Animales , Anticuerpos Neutralizantes/inmunología , Baculoviridae , Células CHO , Cricetinae , Cricetulus , Ensayo de Inmunoadsorción Enzimática , Femenino , Cobayas , Inyecciones Intramusculares , Lípido A/análogos & derivados , Pichia , Reacción en Cadena en Tiempo Real de la Polimerasa , Vacunas Virales/administración & dosificaciónRESUMEN
Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are a mainstay of therapy for treating human immunodeficiency type 1 virus (HIV-1)-infected patients. MK-1439 is a novel NNRTI with a 50% inhibitory concentration (IC50) of 12, 9.7, and 9.7 nM against the wild type (WT) and K103N and Y181C reverse transcriptase (RT) mutants, respectively, in a biochemical assay. Selectivity and cytotoxicity studies confirmed that MK-1439 is a highly specific NNRTI with minimum off-target activities. In the presence of 50% normal human serum (NHS), MK-1439 showed excellent potency in suppressing the replication of WT virus, with a 95% effective concentration (EC95) of 20 nM, as well as K103N, Y181C, and K103N/Y181C mutant viruses with EC95 of 43, 27, and 55 nM, respectively. MK-1439 exhibited similar antiviral activities against 10 different HIV-1 subtype viruses (a total of 93 viruses). In addition, the susceptibility of a broader array of clinical NNRTI-associated mutant viruses (a total of 96 viruses) to MK-1439 and other benchmark NNRTIs was investigated. The results showed that the mutant profile of MK-1439 was superior overall to that of efavirenz (EFV) and comparable to that of etravirine (ETR) and rilpivirine (RPV). Furthermore, E138K, Y181C, and K101E mutant viruses that are associated with ETR and RPV were susceptible to MK-1439 with a fold change (FC) of <3. A two-drug in vitro combination study indicated that MK-1439 acts nonantagonistically in the antiviral activity with each of 18 FDA-licensed drugs for HIV infection. Taken together, these in vitro data suggest that MK-1439 possesses the desired properties for further development as a new antiviral agent.
Asunto(s)
Fármacos Anti-VIH/farmacología , Transcriptasa Inversa del VIH/antagonistas & inhibidores , VIH-1/efectos de los fármacos , Piridonas/farmacología , Triazoles/farmacología , Fármacos Anti-VIH/administración & dosificación , Fármacos Anti-VIH/efectos adversos , Sinergismo Farmacológico , Infecciones por VIH/tratamiento farmacológico , Transcriptasa Inversa del VIH/metabolismo , VIH-1/enzimología , Humanos , Técnicas In Vitro , Macrófagos/efectos de los fármacos , Monocitos/efectos de los fármacos , Piridonas/efectos adversos , Triazoles/efectos adversos , Replicación Viral/efectos de los fármacosRESUMEN
Attempts to develop a vaccine to prevent genital herpes simplex virus 2 (HSV-2) disease have been only marginally successful, suggesting that novel strategies are needed. Immunization with HSV-2 glycoprotein C (gC-2) and gD-2 was evaluated in mice and guinea pigs to determine whether adding gC-2 to a gD-2 subunit vaccine would improve protection by producing antibodies that block gC-2 immune evasion from complement. Antibodies produced by gC-2 immunization blocked the interaction between gC-2 and complement C3b, and passive transfer of gC-2 antibody protected complement-intact mice but not C3 knockout mice against HSV-2 challenge, indicating that gC-2 antibody is effective, at least in part, because it prevents HSV-2 evasion from complement. Immunization with gC-2 also produced neutralizing antibodies that were active in the absence of complement; however, the neutralizing titers were higher when complement was present, with the highest titers in animals immunized with both antigens. Animals immunized with the gC-2-plus-gD-2 combination had robust CD4+ T-cell responses to each immunogen. Multiple disease parameters were evaluated in mice and guinea pigs immunized with gC-2 alone, gD-2 alone, or both antigens. In general, gD-2 outperformed gC-2; however, the gC-2-plus-gD-2 combination outperformed gD-2 alone, particularly in protecting dorsal root ganglia in mice and reducing recurrent vaginal shedding of HSV-2 DNA in guinea pigs. Therefore, the gC-2 subunit antigen enhances a gD-2 subunit vaccine by stimulating a CD4+ T-cell response, by producing neutralizing antibodies that are effective in the absence and presence of complement, and by blocking immune evasion domains that inhibit complement activation.
Asunto(s)
Ganglios Espinales/inmunología , Herpes Genital/prevención & control , Vacuna contra el Herpes Zóster/inmunología , Herpes Zóster/prevención & control , Herpesvirus Humano 2/inmunología , Proteínas del Envoltorio Viral/inmunología , Animales , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/sangre , Linfocitos T CD4-Positivos/inmunología , Femenino , Cobayas , Herpes Genital/inmunología , Herpes Zóster/inmunología , Vacuna contra el Herpes Zóster/administración & dosificación , Inmunización/métodos , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Prevención Secundaria , Vagina/virología , Esparcimiento de VirusRESUMEN
Respiratory syncytial virus (RSV) infection is a major cause of respiratory illness in infants and the elderly. Although several vaccines have been developed, none have succeeded in part due to our incomplete understanding of the correlates of immune protection. While both T cells and antibodies play a role, emerging data suggest that antibody-mediated mechanisms alone may be sufficient to provide protection. Therefore, to map the humoral correlates of immunity against RSV, antibody responses across six different vaccines were profiled in a highly controlled nonhuman primate-challenge model. Viral loads were monitored in both the upper and lower respiratory tracts, and machine learning was used to determine the vaccine platform-agnostic antibody features associated with protection. Upper respiratory control was associated with virus-specific IgA levels, neutralization, and complement activity, whereas lower respiratory control was associated with Fc-mediated effector mechanisms. These findings provide critical compartment-specific insights toward the rational development of future vaccines.
Asunto(s)
Primates/inmunología , Infecciones por Virus Sincitial Respiratorio/inmunología , Infecciones por Virus Sincitial Respiratorio/prevención & control , Vacunas contra Virus Sincitial Respiratorio/inmunología , Virus Sincitial Respiratorio Humano/inmunología , Vacunación , Animales , Anticuerpos Neutralizantes , Anticuerpos Antivirales/sangre , Biomarcadores/sangre , Chlorocebus aethiops , Humanos , Inmunidad Innata , Inmunoglobulina A/sangre , Pulmón/virología , Infecciones por Virus Sincitial Respiratorio/virología , Carga ViralRESUMEN
BACKGROUND: Introduction of rotavirus vaccines in the United States beginning in 2006 led to a rapid decline in the frequency of acute rotavirus gastroenteritis necessitating medical attention. We examined whether serotype replacement was occurring as a result of vaccine use. METHODS: Children with gastroenteritis presenting to CHOP have been tested for rotavirus antigen in the stool. Commencing with the 1999-2000 season, positive specimens were genotyped to establish the G (VP7) and P (VP4) type. RESULTS: In 2009-2010, 4 hospital-acquired and 18 community-acquired cases of rotavirus gastroenteritis were identified at CHOP. For the third consecutive full season since the introduction of rotavirus vaccines, the proportion of annual G3 cases was higher than in the prevaccine era. Although G3 strains caused 50% of the community cases in 2009-10, the absolute number of G3 cases actually dropped from 15 in 2007-08 to 8 and 9 in the 2008-09 and 2009-10 seasons, respectively. P[8] accounted for > 90% of cases seen at CHOP in each of the last 3 seasons, including 20/22 (91%) cases during the 2009-10 season. CONCLUSIONS: Findings to date provide suggestive but still inconclusive evidence for vaccine-driven serotype replacement. Given the increased proportion of G3 cases in the new vaccine era despite the overall marked reduction in rotavirus gastroenteritis, continued surveillance is prudent.
Asunto(s)
Infecciones Comunitarias Adquiridas/epidemiología , Infección Hospitalaria/epidemiología , Gastroenteritis/epidemiología , Hospitales Pediátricos/estadística & datos numéricos , Infecciones por Rotavirus/epidemiología , Vacunas contra Rotavirus/administración & dosificación , Rotavirus/aislamiento & purificación , Adolescente , Antígenos Virales/análisis , Proteínas de la Cápside/análisis , Niño , Preescolar , Infecciones Comunitarias Adquiridas/virología , Infección Hospitalaria/virología , Epidemias , Heces/virología , Gastroenteritis/virología , Genotipo , Humanos , Lactante , Philadelphia/epidemiología , Rotavirus/clasificación , Rotavirus/genética , Infecciones por Rotavirus/virología , Vacunas contra Rotavirus/inmunologíaRESUMEN
A series of HIV-1 protease inhibitors containing an epsilon substituted lysinol backbone was synthesized. Two novel synthetic routes using N-boc-L-glutamic acid alpha-benzyl ester and 2,6-diaminopimelic acid were developed. Incorporation of this epsilon substituent enabled access to the S2 pocket of the enzyme, affording high potency inhibitors. Modeling studies and synthetic efforts suggest the potency increase is due to both conformational bias and van der Waals interactions with the S2 pocket.
Asunto(s)
Inhibidores de la Proteasa del VIH/farmacología , Lisina/análogos & derivados , Inhibidores de la Proteasa del VIH/química , Modelos Moleculares , Relación Estructura-ActividadRESUMEN
Biaryl ethers were recently reported as potent NNRTIs. Herein, we disclose a detailed effort to modify the previously reported compound 1. We have designed and synthesized a series of novel pyrazole derivatives as a surrogate for pyrazolopyridine motif that were potent inhibitors of HIV-1 RT with nanomolar intrinsic activity on the WT and key mutant enzymes and potent antiviral activity in infected cells.
Asunto(s)
Fármacos Anti-VIH/química , Éteres/química , Transcriptasa Inversa del VIH/antagonistas & inhibidores , Pirazoles/química , Piridinas/química , Inhibidores de la Transcriptasa Inversa/química , Regulación Alostérica , Animales , Fármacos Anti-VIH/síntesis química , Fármacos Anti-VIH/farmacocinética , Perros , Éteres/síntesis química , Éteres/farmacocinética , Transcriptasa Inversa del VIH/genética , Transcriptasa Inversa del VIH/metabolismo , Humanos , Mutación , Pirazoles/síntesis química , Pirazoles/farmacocinética , Piridinas/síntesis química , Piridinas/farmacocinética , Ratas , Inhibidores de la Transcriptasa Inversa/síntesis química , Inhibidores de la Transcriptasa Inversa/farmacocinética , Relación Estructura-ActividadRESUMEN
Optimization studies using an HIV RNase H active site inhibitor containing a 1-hydroxy-1,8-naphthyridin-2(1H)-one core identified 4-position substituents that provided several potent and selective inhibitors. The best compound was potent and selective in biochemical assays (IC(50)=0.045 µM, HIV RT RNase H; 13 µM, HIV RT-polymerase; 24 µM, HIV integrase) and showed antiviral efficacy in a single-cycle viral replication assay in P4-2 cells (IC(50)=0.19 µM) with a modest window with respect to cytotoxicity (CC(50)=3.3 µM).
Asunto(s)
Fármacos Anti-VIH/farmacología , Inhibidores Enzimáticos/farmacología , VIH-1/enzimología , Ribonucleasa H/antagonistas & inhibidores , Fármacos Anti-VIH/química , Inhibidores Enzimáticos/química , Células HeLa , Humanos , Naftiridinas/química , Naftiridinas/farmacologíaRESUMEN
The RSV Fusion (F) protein is a target for neutralizing antibody responses and is a focus for vaccine discovery; however, the process of RSV entry requires F to adopt a metastable prefusion form and transition to a more stable postfusion form, which displays less potent neutralizing epitopes. mRNA vaccines encode antigens that are translated by host cells following vaccination, which may allow conformational transitions similar to those observed during natural infection to occur. Here we evaluate a panel of chemically modified mRNA vaccines expressing different forms of the RSV F protein, including secreted, membrane associated, prefusion-stabilized, and non-stabilized structures, for conformation, immunogenicity, protection, and safety in rodent models. Vaccination with mRNA encoding native RSV F elicited antibody responses to both prefusion- and postfusion-specific epitopes, suggesting that this antigen may adopt both conformations in vivo. Incorporating prefusion stabilizing mutations further shifts the immune response toward prefusion-specific epitopes, but does not impact neutralizing antibody titer. mRNA vaccine candidates expressing either prefusion stabilized or native forms of RSV F protein elicit robust neutralizing antibody responses in both mice and cotton rats, similar to levels observed with a comparable dose of adjuvanted prefusion stabilized RSV F protein. In contrast to the protein subunit vaccine, mRNA-based vaccines elicited robust CD4+ and CD8+ T-cell responses in mice, highlighting a potential advantage of the technology for vaccines requiring a cellular immune response for efficacy.
RESUMEN
Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are the mainstays of therapy for the treatment of human immunodeficiency virus type 1 (HIV-1) infections. However, the effectiveness of NNRTIs can be hampered by the development of resistance mutations which confer cross-resistance to drugs in the same class. Extensive efforts have been made to identify new NNRTIs that can suppress the replication of the prevalent NNRTI-resistant viruses. MK-4965 is a novel NNRTI that possesses both diaryl ether and indazole moieties. The compound displays potency at subnanomolar concentrations against wild-type (WT), K103N, and Y181C reverse transcriptase (RT) in biochemical assays. MK-4965 is also highly potent against the WT virus and two most prevalent NNRTI-resistant viruses (viruses that harbor the K103N or the Y181C mutation), against which it had 95% effective concentrations (EC(95)s) of <30 nM in the presence of 10% fetal bovine serum. The antiviral EC(95) of MK-4965 was reduced approximately four- to sixfold when it was tested in 50% human serum. Moreover, MK-4965 was evaluated with a panel of 15 viruses with NNRTI resistance-associated mutations and showed a superior mutant profile to that of efavirenz but not to that of etravirine. MK-4965 was similarly effective against various HIV-1 subtypes and viruses containing nucleoside reverse transcriptase inhibitor or protease inhibitor resistance-conferring mutations. A two-drug combination study showed that the antiviral activity of MK-4965 was nonantagonistic with each of the 18 FDA-licensed drugs tested vice versa in the present study. Taken together, these in vitro data show that MK-4965 possesses the desired properties for further development as a new NNRTI for the treatment of HIV-1 infection.
Asunto(s)
Fármacos Anti-VIH/farmacología , Transcriptasa Inversa del VIH/antagonistas & inhibidores , VIH-1/efectos de los fármacos , Pirazoles/farmacología , Piridinas/farmacología , Inhibidores de la Transcriptasa Inversa/farmacología , Alquinos , Benzoxazinas/farmacología , Línea Celular , Ciclopropanos , Farmacorresistencia Viral , Humanos , Nevirapina/farmacología , Nitrilos , Piridazinas/farmacología , PirimidinasRESUMEN
Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are key elements of multidrug regimens, called HAART (Highly Active Antiretroviral Therapy), that are used to treat HIV-1 infections. Elucidation of the structure-activity relationships of the thiocarbamate moiety of the previous published lead compound 2 provided a series of novel tetrahydroquinoline derivatives as potent inhibitors of HIV-1 RT with nanomolar intrinsic activity on the WT and key mutant enzymes and potent antiviral activity in infected cells. The SAR optimization, mutation profiles, preparation of compounds, and pharmacokinetic profile of compounds are described.
Asunto(s)
Fármacos Anti-VIH/química , Transcriptasa Inversa del VIH/antagonistas & inhibidores , Quinolinas/química , Inhibidores de la Transcriptasa Inversa/química , Sitio Alostérico , Fármacos Anti-VIH/síntesis química , Fármacos Anti-VIH/farmacología , Sitios de Unión , Cristalografía por Rayos X , Transcriptasa Inversa del VIH/metabolismo , Conformación Molecular , Proteínas Mutantes/antagonistas & inhibidores , Proteínas Mutantes/metabolismo , Quinolinas/síntesis química , Quinolinas/farmacología , Inhibidores de la Transcriptasa Inversa/síntesis química , Inhibidores de la Transcriptasa Inversa/farmacología , Relación Estructura-Actividad , Tiocarbamatos/química , Tiocarbamatos/farmacologíaRESUMEN
Viral plaque assays are important tools in the development and evaluation of new antiviral drugs or vaccines in both preclinical and clinical research. While plaque assays are the standard tools to measure infectious virus, the methodology is time-consuming and requires experience in recognizing plaques. The assays are also prone to variation among analysts due to plaque recognition and manual counting errors. Here we describe the development of two simplified plaque assays for measuring RSV virus titers and anti-RSV antibody neutralization titers using 96 well plate formats. First, we evaluated multiple parameters to build up a quantitative plaque assay to measure infectious RSV. We then optimized the assay conditions to assess the fundamental changes from the traditional plaque assay, which were elimination of overnight pre-seeding host cells and addition of a centrifugation step after viral infection of the cells. We designed DoE to refine four key parameters within one experiment for host cell density, host cell volume, viral inoculum volume, host cell and viral mixture incubation time to make this assay more robust. We have also adapted these conditions into a second assay, which was an automated plaque reduction neutralization assay (PRNT) to determine neutralization titers of anti-RSV antibodies. Both assays utilize immune fluorescence staining to detect viral plaques. The images of the immuno-stained wells are captured by the PerkinElmer EnSight instrument and show clear visualization of plaques harvesting on day 3. Software algorithm was specifically designed for automatic counting of these fluorescent "objects". The quantitative plaque assay provided titers of RSV similar to those obtained from the traditional plaque assay. The method has been successfully utilized to screen multiple vaccine candidates in viral shedding efficacy studies. The automated PRNT assay provided antibody neutralizing titers that matched with published data. This automated 96 well plaque assay has made it possible to screen RSV samples in a higher throughput manner, and can be extended to other infectious organisms that form plaques for vaccine or drug evaluation.
Asunto(s)
Ensayos Analíticos de Alto Rendimiento/métodos , Imagen Óptica , Infecciones por Virus Sincitial Respiratorio/virología , Virus Sincitiales Respiratorios/crecimiento & desarrollo , Ensayo de Placa Viral/métodos , Algoritmos , Animales , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/sangre , Línea Celular Tumoral , Modelos Animales de Enfermedad , Evaluación de Medicamentos , Femenino , Humanos , Pruebas de Neutralización , Reproducibilidad de los Resultados , Infecciones por Virus Sincitial Respiratorio/inmunología , Virus Sincitiales Respiratorios/inmunología , Sigmodontinae/inmunología , Sigmodontinae/virología , Vacunas Virales/administración & dosificación , Vacunas Virales/inmunologíaRESUMEN
Respiratory syncytial virus (RSV) infection is the leading cause of hospitalization and infant mortality under six months of age worldwide; therefore, the prevention of RSV infection in all infants represents a significant unmet medical need. Here we report the isolation of a potent and broadly neutralizing RSV monoclonal antibody derived from a human memory B-cell. This antibody, RB1, is equipotent on RSV A and B subtypes, potently neutralizes a diverse panel of clinical isolates in vitro and demonstrates in vivo protection. It binds to a highly conserved epitope in antigenic site IV of the RSV fusion glycoprotein. RB1 is the parental antibody to MK-1654 which is currently in clinical development for the prevention of RSV infection in infants.
Asunto(s)
Anticuerpos Antivirales/inmunología , Anticuerpos ampliamente neutralizantes/inmunología , Secuencia Conservada , Glicoproteínas/inmunología , Virus Sincitial Respiratorio Humano/inmunología , Proteínas Virales de Fusión/inmunología , Animales , Anticuerpos Monoclonales/aislamiento & purificación , Linfocitos B/inmunología , Sitios de Unión , Modelos Animales de Enfermedad , Epítopos/inmunología , Femenino , Humanos , Memoria Inmunológica , Modelos Moleculares , Unión Proteica , SigmodontinaeRESUMEN
BACKGROUND: Rotavirus is the most common etiologic agent of healthcare-acquired diarrhea in pediatric patients. There has been little published information on healthcare-acquired rotavirus infection. METHODS: This was a retrospective cohort study of children hospitalized with rotavirus gastroenteritis at our institution between December 1999 and May 2004. Patients with community- and healthcare-acquired rotavirus gastroenteritis were compared with regards to age, time of infection, patient unit, and viral subtype as determined by reverse transcription polymerase chain reaction sequencing. RESULTS: Five hundred seventy-seven children were hospitalized with rotavirus gastroenteritis during the study period. One hundred twenty-one (21%) of these infections were healthcare-acquired. The incidence of healthcare-acquired infection was 4.2 cases per 10,000 patient-days. With the exception of 1 outbreak on an isolated patient unit, community- and healthcare-acquired disease affected similar patient populations, had the same temporal distribution, and were caused by viruses with similar subtypes. However, there was a significant difference between the geographic distribution of community- and healthcare-acquired disease within the hospital (P < 0.001). The majority (83%) of community-acquired cases were admitted to general medicine-surgery units, but only 53% of the healthcare-acquired cases occurred on these units (P = 0.005). The remaining healthcare-acquired infections occurred on units that rarely admitted patients with community-acquired disease. CONCLUSIONS: Healthcare-acquired rotavirus gastroenteritis seems to be caused by repeated introduction of community strains into the hospital setting. Heightened attention to infection control practices and rapid rotavirus identification is necessary on all units, especially those that infrequently admit children with rotavirus gastroenteritis, to prevent the spread of healthcare-acquired disease.
Asunto(s)
Infecciones Comunitarias Adquiridas/epidemiología , Infección Hospitalaria/epidemiología , Gastroenteritis/epidemiología , Infecciones por Rotavirus/epidemiología , Rotavirus/clasificación , Rotavirus/genética , Adolescente , Niño , Preescolar , Estudios de Cohortes , Infecciones Comunitarias Adquiridas/virología , Infección Hospitalaria/virología , Brotes de Enfermedades , Gastroenteritis/virología , Genotipo , Humanos , Lactante , Recién Nacido , Epidemiología Molecular , ARN Viral/genética , Estudios Retrospectivos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Rotavirus/aislamiento & purificación , Infecciones por Rotavirus/virologíaRESUMEN
A series of 10-hydroxy-7,8-dihydropyrazino[1',2':1,5]pyrrolo[2,3-d]pyridazine-1,9(2H,6H)-diones was synthesized and tested for their inhibition of HIV-1 replication in cell culture. Structure-activity studies indicated that high antiviral potency against wild-type virus as well as viruses containing integrase mutations that confer resistance to three different structural classes of integrase inhibitors could be achieved by incorporation of small aliphatic groups at certain positions on the core template. An optimal compound from this study, 16, inhibits integrase strand-transfer activity with an IC(50) value of 10 nM, inhibits HIV-1 replication in cell culture with an IC(95) value of 35 nM in the presence of 50% normal human serum, and displays modest pharmacokinetic properties in rats (i.v. t(1/2)=5.3 h, F=17%).
Asunto(s)
Química Farmacéutica/métodos , Integrasa de VIH/síntesis química , Integrasa de VIH/farmacología , Integrasas/genética , Mutación , Administración Oral , Animales , Antivirales/farmacología , Disponibilidad Biológica , Diseño de Fármacos , Humanos , Concentración 50 Inhibidora , Modelos Químicos , Ratas , Relación Estructura-Actividad , Replicación ViralRESUMEN
Respiratory syncytial virus (RSV) is a leading cause of serious lower respiratory tract disease in young children and older adults throughout the world. Prevention of severe RSV disease through active immunization is optimal but no RSV vaccine has been licensed so far. Immune mechanisms of protection against RSV infection in humans have not been fully established, thus a comprehensive characterization of virus-specific immune responses in a relevant animal model will be beneficial in defining correlates of protection. In this study, we infected juvenile naive AGMs with RSV A2 strain and longitudinally assessed virus-specific humoral and cellular immune responses in both peripheral blood and the respiratory tract. RSV viral loads at nasopharyngeal surfaces and in the lung peaked at around day 5 following infection, and then largely resolved by day 10. Low levels of neutralizing antibody titers were detected in serum, with similar kinetics as RSV fusion (F) protein-binding IgG antibodies. RSV infection induced CD8+, but very little CD4+, T lymphocyte responses in peripheral blood. Virus-specific CD8+ T cell frequencies were ~10 fold higher in bronchoaveolar lavage (BAL) compared to peripheral blood and exhibited effector memory (CD95+CD28-) / tissue resident memory (CD69+CD103+) T (TRM) cell phenotypes. The kinetics of virus-specific CD8+ T cells emerging in peripheral blood and BAL correlated with declining viral titers, suggesting that virus-specific cellular responses contribute to the clearance of RSV infection. RSV-experienced AGMs were protected from subsequent exposure to RSV infection. Additional studies are underway to understand protective correlates in these seropositive monkeys.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Inmunidad Celular , Memoria Inmunológica , Pulmón/inmunología , Infecciones por Virus Sincitial Respiratorio/inmunología , Virus Sincitiales Respiratorios/inmunología , Animales , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Antígenos CD/sangre , Antígenos CD/inmunología , Recuento de Linfocito CD4 , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Linfocitos T CD8-positivos/metabolismo , Chlorocebus aethiops , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Pulmón/metabolismo , Infecciones por Virus Sincitial Respiratorio/sangre , Virus Sincitiales Respiratorios/metabolismoRESUMEN
Monitoring antigen-specific memory B cells and the antibodies they encode is important for understanding the specificity, breadth and duration of immune response to an infection or vaccination. The antibodies isolated could further help design vaccine antigens for raising relevant protective immune responses. However, developing assays to measure and isolate antigen-specific memory B cells is technically challenging due to the low frequencies of these cells that exist in the circulating blood. Here, we describe a flow cytometry method to identify and isolate dengue envelope-specific memory B cells using a labeled dengue envelope protein. We enumerated dengue-envelope specific memory B cells from a cohort of dengue seropositive donors using this direct flow cytometry assay. A more established and conventional assay, the cultured B ELISPOT, was used as a benchmark comparator. Furthermore, we were able to confirm the single-sorted memory B-cell specificity by culturing B cells and differentiating them into plasma cells using cell lines expressing CD40L. The culture supernatants were assayed for antigen binding and the ability of the antibodies to neutralize the cognate dengue virus. Moreover, we successfully isolated the heavy and light Ig sequences and expressed them as full-length recombinant antibodies to reproduce the activity seen in culture supernatants. Mapping of these antibodies revealed a novel epitope for dengue 2 virus serotype. In conclusion, we established a reproducible methodology to enumerate antigen-specific memory B cells and assay their encoded antibodies for functional characterization.