Intranasal M2SR (M2-Deficient Single Replication) H3N2 Influenza Vaccine Provides Enhanced Mucosal and Serum Antibodies in Adults

BACKGROUND

We previously demonstrated that an intranasal dose of 108 50% tissue culture infectious dose (TCID50) M2-deficient single replication (M2SR) influenza vaccine protected against highly drifted H3N2 influenza challenge in a subset of subjects who demonstrated ≥2-fold increase in microneutralization (MN) antibodies to Belgium2015 (the challenge strain) after vaccination. Here, we describe a phase 1b, observer-blinded, dose-escalation study demonstrating an increased proportion of responders with this signal of immune protection.

METHODS

Serosusceptible subjects aged 18-49 years were randomized to receive 2 doses (108-109 TCID50) of M2SR or placebo administered 28 days apart. Clinical specimens were collected before and after each dose. The primary objective was to demonstrate safety of M2SR vaccines.

RESULTS

The vaccine was well tolerated at all dose levels. Against Belgium2015, ≥ 2-fold increases in MN antibodies were noted among 40% (95% confidence interval [CI], 24.9%-56.7%) of subjects following a single 108 TCID50 M2SR dose and among 80.6% (95% CI, 61.4%-92.3%) after 109 dose (P < .001). A single 109 TCID50 dose of M2SR generated ≥4-fold hemagglutination inhibition antibody seroconversion against the vaccine strain in 71% (95% CI, 52.0%-85.8%) of recipients. Mucosal and cellular immune responses were also induced.

CONCLUSIONS

These results indicate that M2SR may provide substantial protection against infection with highly drifted strains of H3N2 influenza.

CLINICAL TRIALS REGISTRATION

NCT03999554.

Single Replication M2SR Influenza Vaccine Induced Immune Responses Associated with Protection Against Human Challenge with Highly Drifted H3N2 Influenza Strain

Background

Current influenza vaccines are strain specific and demonstrate low vaccine efficacy against H3N2 influenza disease, especially when vaccine is mismatched to circulating virus. The novel influenza vaccine candidate, M2-deficient single replication (M2SR), induces a broad, multi-effector immune response.

Methods

A phase 2 challenge study was conducted to assess the efficacy of an M2SR vaccine expressing hemagglutinin and neuraminidase from A/Brisbane/10/2007 (Bris2007 M2SR H3N2; clade 1). Four weeks after vaccination, recipients were challenged with antigenically distinct H3N2 virus (A/Belgium/4217/2015, clade 3C.3b) and assessed for infection and clinical symptoms.

Results

Adverse events after vaccination were mild and similar in frequency for placebo and M2SR recipients. A single dose of Bris2007 M2SR induced neutralizing antibody to the vaccine (48% of recipients) and challenge strain (27% of recipients). Overall, 54% of M2SR recipients were infected after challenge, compared with 71% of placebo recipients. The subset of M2SR recipients with a vaccine-induced microneutralization response against the challenge virus had reduced rates of infection after challenge (38% vs 71% of placebo recipients; P = .050) and reduced illness.

Conclusions

Study participants with vaccine-induced neutralizing antibodies were protected against infection and illness after challenge with an antigenically distinct virus. This is the first demonstration of vaccine-induced protection against a highly drifted H3N2 challenge virus.

33. Intranasal M2SR (M2-deficient Single Replication) Live H3N2 Influenza Investigational Vaccine Induces Serum HAI & Broad Immune Responses in High Proportion of Adults

Background

A single intranasal (IN) dose of 10⁸ TCID₅₀ M2SR protected a responder subset of adults against infection and disease in a prior human influenza challenge study (EudraCT number: 2017-004971-30). Higher dose levels of M2SR were assessed in this phase 1b study to enhance immune responses and further increase protection levels in adults.

Methods

A double-blind, randomized, placebo-controlled dose escalation study (NCT03999554) was conducted at 4 US study sites with two different H3N2 M2SR vaccines that contained HA & NA from either A/Brisbane/10/2007 or A/Singapore/INFIMH-16–0019/2016. Serosusceptible 18–49 year old subjects (n = 206) received 2 IN doses of either saline or 1 of 3 different dose levels of vaccine (10⁸ – 10⁹ TCID₅₀), administered 28 days apart.

Results

Study vaccination was well-tolerated at all dose levels. A single 10⁹ dose of A/Singapore/2016 M2SR generated significantly increased serum HAI responses compared to the 108 dose of A/Brisbane/10/2007 M2SR that had provided protection against infection & illness in an earlier human influenza challenge study (Fig. 1). HAI titers ≥40 were achieved in 0%, 23% & 58% of subjects after the first dose of placebo, 10⁸ or 10⁹ M2SR, respectively (p< 0.003). Increases also were stimulated in serum microneutralization titers (MNT) to drifted strains of H3N2 (Fig 2) & in serum NAI (Fig 3) and mucosal sIgA (Fig 4) titers. Further increases in serum and mucosal immune response were noted after a 2^nd IN vaccination.

Proportion of subjects with seroprotective HAI titers after vaccination

Proportion of subjects with increased microneutralization titers against drifted H3N2 viruses after vaccination

Geometric mean fold rise in serum neuraminidase inhibition antibody titers after vaccination

Conclusion

An earlier clinical trial with a 10⁸ dose of M2SR provided protection against infection and illness upon challenge with a highly drifted strain of H3N2. Protection correlated with vaccine induced serum MNT responses. In the current study, a single, 10⁹ dose of M2SR significantly increased serum MNT, HAI & NAI titers as well as mucosal immune responses among greater proportions of study subjects. Since HAI, alone, is a well-accepted surrogate marker for vaccine protection against influenza, these broader enhancements indicate the potential for M2SR to protect against both matched and drifted strains of influenza in a high proportion of adults and strongly support clinical assessment in younger and older age groups as well as development of multivalent M2SR.

Geometric mean fold rise in nasal mucosal secretory IgA antibody titers after vaccination

Disclosures

Joseph Eiden, MD, PhD, FluGen (Consultant) Ruth Ellis, MD, FluGen (Consultant) Roger Aitchison, ScM, FluGen (Consultant) Renee Herber, BS, FluGen (Employee) Pamuk Bilsel, PhD, FluGen (Employee)

Persistence of Immune Responses Through 36 Months in Healthy Adults After Vaccination With a Novel Staphylococcus aureus 4-Antigen Vaccine (SA4Ag)

Background

Staphylococcus aureus causes serious health care- and community-associated disease, requiring improved preventive measures such as vaccines. The investigational S. aureus 4-antigen vaccine (SA4Ag), comprising capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to CRM₁₉₇, recombinant mutant clumping factor A (rmClfA), and recombinant manganese transporter protein C (rP305A or rMntC), was well tolerated, inducing robust functional immune responses to all 4 antigens through 12 months postvaccination. This is a serological extension study through 36 months postvaccination.

Methods

In 2 previous studies, healthy adults received SA4Ag, SA3Ag (without rMntC), or placebo; serology was also assessed at ~24 and ~36 months postvaccination. Functional immune responses (antibody responses that facilitate killing of S. aureus or neutralize S. aureus virulence mechanisms) were assessed with opsonophagocytic activity killing assays (CP5 or CP8) and a fibrinogen-binding inhibition assay (ClfA). A competitive Luminex immunoassay assessed ClfA and rMntC responses. Adverse events within 48 hours of blood draw were recorded.

Results

Four hundred forty subjects (18-64 years old, 255; 65-85 years old, 185) were enrolled. At 24 and 36 months postvaccination, subjects receiving SA4Ag had substantially higher geometric mean titers (GMTs) for CP5, CP8, and ClfA vs baseline; geometric mean fold rises (GMFRs) from baseline to month 36 were 2.7-8.1. For rMntC, 36-month GMTs declined from peak levels but remained above baseline for all SA4Ag groups; GMFRs from baseline to month 36 were 1.8 and 1.5 in the younger and older cohorts, respectively.

Conclusions

Persistent functional immune responses to S. aureus antigens were observed through 36 months in healthy adults.

ClinicalTrialsgov

NCT01643941 and NCT01364571.

2722. Effects of Sex, Age, and Race on Immunogenicity of MenB-FHbp, a Bivalent Meningococcal B Vaccine: A Pooled Evaluation of Clinical Trial Data

Background

MenB-FHbp (bivalent rLP2086), a meningococcal serogroup B vaccine, is approved in several countries for adolescents and young adults. MenB-FHbp elicited robust immune responses and had an acceptable safety profile during an extensive clinical development program. Because immune responses to vaccines can vary by subject demographics, this subgroup analysis pooled data across 7 randomized MenB-FHbp clinical studies to evaluate potential differences in immunogenicity by sex, age, or race/ethnicity in a larger dataset relative to individual studies.

Methods

Data from subjects who received 120 µg MenB-FHbp at 0, 2, and 6 months and had valid immunogenicity results for 4 vaccine-heterologous test strains were included. Immune responses were evaluated by serum bactericidal assays using human complement (hSBA). Immunogenicity endpoints (assessed 1 month after dose 3) were percentages of subjects achieving ≥ 4-fold rise in hSBA titer against each strain, percentages achieving hSBA titers ≥ the lower limit of quantification (LLOQ) against each strain and against all 4 strains combined (composite response), geometric mean hSBA titers against each strain, and percentages achieving hSBA titers ≥ 1:4 (correlate of protection) against each strain.

Results

This analysis included 8026 subjects aged 10‒25 years (51.7% males, 80.7% adolescents aged 10‒18 years, 87.0% white, 9.3% black, 0.8% Asian, 3.0% other race). One month after dose 3, percentages of subjects achieving a ≥ 4-fold rise from baseline titer against each strain and achieving a composite response were similar across age and race (table). A marginally greater percentage of males vs. females achieved ≥ 4-fold rise in titer against each strain, but these differences were not considered clinically meaningful because of the high percentages of responders in both groups.

Conclusion

MenB-FHbp immunogenicity was similar across sex, age, and race in this pooled analysis, with high percentages of responders in all evaluated subgroups. The marginally lower response rates among females compared with males were not considered clinically meaningful. These findings support currently recommended MenB-FHbp vaccination practices without modification by sex, age, or race.

Funding: Pfizer

Disclosures

All authors: No reported disclosures.

2748. Single Intranasal (IN) Dose of M2SR (M2-Deficient Single Replication) Live Influenza Vaccine Protects Adults Against Subsequent Challenge with a Substantially Drifted H3N2 Strain

Background

Demonstration of protection by a M2SR (M2 deficient Single Replication) monovalent H3N2 vaccine was assessed in a phase 2a clinical trial in which the challenge virus was substantially drifted from the vaccine. M2SR is an investigational, live virus vaccine containing hemagglutinin (HA) and neuraminidase (NA) selected from targeted Type A influenza strains. M2SR undergoes only a single round of infection in the respiratory epithelium but evokes an immune response profile similar to wild-type influenza virus and protects ferrets against both homologous and heterologous influenza variants.

Methods

A blinded, randomized, placebo-controlled human challenge study (EudraCT #: 2017-004971-30) was conducted with M2SR containing HA and NA from A/Brisbane/10/2007 (H3N2). 18–55-year-old subjects received 1 IN dose of saline or 10⁸ TCID₅₀ of vaccine. 4 weeks later, 99 subjects were challenged IN with 10⁶ TCID₅₀ H3N2 A/Belgium/4217/2015 (Figures 1 and 2).

Results

Adverse events (AE) were similar between placebo (N = 51) and M2SR recipients (N = 48) during the 28 days after immunization. After challenge with A/Belgium/4217/2015, 35% of M2SR recipients experienced influenza infection and illness, compared with 49% of placebo subjects (Figure 3). An 18% reduction in viral load was noted after challenge for M2SR subjects. Serum microneutralization response to vaccine was detected in 54% of M2SR subjects (vs. 0/51 placebo subjects), and among these subjects a 34% reduction in viral load and 51% reduction in symptom scores was noted after challenge vs placebo. Among the 29% of subjects with post-vaccine response to both vaccine and challenge strains, a 62% reduction in viral load and 56% reduction in symptom scores was noted after challenge with highly drifted H3N2 (Figure 4).

Conclusion

One dose of M2SR protected healthy adults against influenza infection and illness with a highly drifted challenge strain. This is believed to be the first study to demonstrate protection against challenge with an influenza strain substantially different from the vaccine and indicates potential for improved breadth of protection by M2SR compared with current vaccines. The mild vaccine AE profile supports clinical trials of additional dose levels and regimens to enhance drifted strain protection by M2SR.

Disclosures

All authors: No reported disclosures.

S. aureus colonization in healthy Australian adults receiving an investigational S. aureus 3-antigen vaccine

OBJECTIVES

Assess Staphylococcus aureus (S. aureus) colonization in healthy Australian adults receiving an investigational S. aureus 3-antigen vaccine (SA3Ag).

METHODS

In this phase 1, double-blind, sponsor-unblinded study, participants were randomized to receive a single dose (1 of 3 dose levels) of SA3Ag or placebo and a booster dose or placebo at 6 months. S. aureus isolates from nasal, perineal, and oropharyngeal swabs before and through 12 months post-vaccination were identified.

RESULTS

Baseline S. aureus colonization prevalence was 30.6% (any site), with nasal carriage (27.0%) more common than oropharyngeal/perineal (3.2% each). Following initial vaccination (low-dose: 102; mid-dose: 101; high-dose: 101; placebo: 102) and booster (low-dose: 45; mid-dose: 44; high-dose: 27; placebo: 181), placebo and SA3Ag groups showed similar S. aureus carriage through 12 months. Most colonized participants (74.0%) were colonized by single spa types. Placebo and SA3Ag groups had similar persistence of colonization, with 19.6-30.7% due to single spa types. Acquisition was observed in mid- and high-dose recipients (∼20%) and low-dose and placebo recipients (∼12%). Vaccination resulted in substantial increases in antibodies to all 3 antigens, irrespective of carriage status.

CONCLUSIONS

Based on descriptive analyses of this small study, SA3Ag vaccination did not impact S. aureus acquisition or carriage. Carriage status did not impact antibody responses to SA3Ag.

1970. Phase 1 Clinical Trial of Intranasal Immunization with M2-Deficient, Single Replication, Live Influenza Vaccine (M2SR): Safety and Immune Response in Adults

Background

Influenza vaccines are needed with greater effectiveness and breadth of coverage. FluGen is developing M2SR (M2 deficient Single Replication), an investigational, live virus vaccine. M2SR contains the internal proteins of donor A/Puerto Rico/8/34 and hemagglutinin (HA) and neuraminidase (NA) selected from targeted Type A influenza strains. M2SR undergoes only a single round of infection in the respiratory epithelium but evokes an immune response profile similar to wild-type influenza viruses. In influenza naïve and pre-immune ferrets, M2SR protects against multiple influenza A subtypes.

Methods

A Phase 1, first-in-human, randomized, placebo-control study (FluGen-H3N2-V001; ClinicalTrials.gov identifier NCT02822105) was conducted at a single USA site, with 96 adults, ages 18–49 years. Study vaccine contained HA and NA from A/Brisbane/10/2007 (H3N2). Study volunteers received a single intranasal (IN) inoculation with either M2SR at dose levels of 10⁶, 10⁷ or 10⁸ TCID₅₀ or saline placebo (N = 24/cohort). Study subjects were evaluated for virus replication and solicited local and systemic reactions for 7 days, all adverse events (AE) for 28 days and serious AE (SAE) for 180 days.

Results

No infectious virus was detected in nasal swabs from any vaccinated subject. The most commonly reported AE was mild nasal rhinorrhea/congestion during the first 7 days after vaccination (Figure 1). No subject had fever or a severe reaction to the vaccine. No SAEs were reported. At least one AE was reported among 29%, 58%, and 83% of M2SR subjects administered 10⁶, 10⁷, or 10⁸ TCID₅₀, respectively, and 46% among placebo subjects. There were no notable imbalances among study groups for other events. T- and B-cell responses, including influenza-specific serum and mucosal antibody responses were detected at a significantly higher frequency among vaccine than placebo subjects (Figure 2).

Conclusion

M2SR vaccine was safe and well tolerated at all dose levels, generated a dose-response effect for humoral (HA antibody) and mucosal antibodies against both homologous and heterologous influenza variants, and elicited robust T-cell responses. No infectious virus was detected in nasal swabs from any vaccinated subject.

Disclosures

J. Eiden, FluGen, Inc.: Consultant, Consulting fee and Stock Options. G. Gordon, FluGen: Consultant, Consulting fee. C. Fierro, FluGen: Investigator, Fee for service. R. Belshe, FluGen: Consultant, Consulting fee and Stock Options. H. Greenberg, FluGen: Consultant, Consulting fee and Stock OpTions. D. Hoft, FluGen: Research Contractor, Fee for service. Y. Hatta, FluGen: Employee, Salary and Stock Options. M. Imboden, FluGen: Employee, Salary and Stock Options. M. Moser, FluGen: Employee, Salary and Stock Options. R. Herber, FluGen: Employee, Salary and Stock Options. D. Boltz, FluGen: Research Contractor, fee for service. M. Tary-Lehmann, FluGen: Research Contractor, Fee for service. CTL: Founder and Owner, Salary. Y. Kawaoka, FluGen: Founder, Stock Options. G. Neumann, FluGen: Founder, Stock Options. P. Radspinner, FluGen: Board Member and Founder, Salary and Stock Options. R. Aitchison, FluGen: Consultant, Consulting fee. P. Bilsel, FluGen: Employee, Salary and Stock Options.

Safety, tolerability, and immunogenicity of a novel 4-antigen Staphylococcus aureus vaccine (SA4Ag) in healthy Japanese adults

A novel Staphylococcus aureus 4-antigen vaccine (SA4Ag) is under development, comprising capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to CRM197, recombinant protein clumping factor A (rmClfA), and recombinant manganese transporter protein C (MntC). We evaluated SA4Ag safety, tolerability, and immunogenicity in Japanese adults aged 20 to 64 and 65 to 85 years. A total of 136 healthy Japanese adults (68 per age group) were randomized 1:1 to receive single-dose SA4Ag or placebo intramuscularly (Day 1). Safety assessments included reactogenicity and adverse events. The ability of the vaccine to induce immune responses that are considered functional due to their ability to facilitate the killing of S. aureus or neutralize S. aureus virulence mechanisms was assessed using 5 different antigen-specific assays. SA4Ag was well tolerated in both age groups, with no safety concerns. At Day 29, > 85% of SA4Ag recipients in each age group achieved predefined thresholds for each antigen. Antibody geometric mean-fold rises from baseline to Day 29 in SA4Ag groups were: > 80 and > 30 for CP5 and CP8 (opsonophagocytic activity assay), > 10 for ClfA (fibrinogen-binding inhibition assay), and > 15 and > 7 for ClfA and MntC (competitive Luminex® immunoassay), respectively. Antibody titers decreased through Month 12 but remained well above baseline and placebo levels. SA4Ag had an acceptable safety profile and induced rapid and robust functional immune responses in both age groups. These results support ongoing development of SA4Ag for the prevention of invasive S. aureus disease in elective-surgery patients in Japan, North America, and Europe.

Meningococcal carriage in Dutch adolescents and young adults; a cross-sectional and longitudinal cohort study

OBJECTIVES

Current information on rates and dynamics of meningococcal carriage is essential for public health policy. This study aimed to determine meningococcal carriage prevalence, its risk factors and duration in the Netherlands, where meningococcal C vaccine coverage is >90%. Several methods to identify serogroups of meningococcal carriage isolates among adolescent and young adults were compared.

METHODS

Oropharyngeal swabs were collected from 1715 participants 13-23 years of age in 2013-2014; 300 were prospectively followed over 8 months. Cultured isolates were characterized by Ouchterlony, real-time (rt-) PCR or whole-genome sequencing (WGS). Direct swabs were assessed by rt-PCR. Questionnaires on environmental factors and behaviour were also obtained.

RESULTS

A meningococcal isolate was identified in 270/1715 (16%) participants by culture. Of MenB isolates identified by whole genome sequencing, 37/72 (51%) were correctly serogrouped by Ouchterlony, 46/51 (90%) by rt-PCR of cultured isolates, and 39/51 (76%) by rt-PCR directly on swabs. A sharp increase in carriage was observed before the age of 15 years. The age-related association disappeared after correction for smoking, level of education, frequent attendance to crowded social venues, kissing in the previous week and alcohol consumption. Three participants carried the same strain identified at three consecutive visits in an 8-month period. In these isolates, progressively acquired mutations were observed.

CONCLUSIONS

Whole genome sequencing of culture isolates was the most sensitive method for serogroup identification. Based upon results of this study and risk of meningococcal disease, an adolescent meningococcal vaccination might include children before the age of 15 years to confer individual protection and potentially to establish herd protection.

SA4Ag, a 4-antigen Staphylococcus aureus vaccine, rapidly induces high levels of bacteria-killing antibodies

BACKGROUND

Staphylococcus aureus is a leading cause of healthcare-associated infections. No preventive vaccine is currently licensed. SA4Ag is an investigational 4-antigen S. aureus vaccine, composed of capsular polysaccharide conjugates of serotypes 5 and 8 (CP5 and CP8), recombinant surface protein clumping factor A (rmClfA), and recombinant manganese transporter protein C (rMntC). This Phase 1 study aimed to confirm the safety and immunogenicity of SA4Ag produced by the final manufacturing process before efficacy study initiation in a surgical population.

METHODS

Healthy adults (18-<65years) received one intramuscular SA4Ag injection. Serum functional antibodies were measured at baseline and Day 29 post-vaccination. An opsonophagocytic activity (OPA) assay measured the ability of vaccine-induced antibodies to CP5 and CP8 to kill S. aureus clinical isolates. For MntC and ClfA, antigen-specific immunogenicity was assessed via competitive Luminex® immunoassay (cLIA) and via fibrinogen-binding inhibition (FBI) assay for ClfA only. Reactogenicity and adverse event data were collected.

RESULTS

One hundred participants were vaccinated. SA4Ag was well tolerated, with a satisfactory safety profile. On Day 29, OPA geometric mean titers (GMTs) were 45,738 (CP5, 95% CI: 38,078-54,940) and 42,652 (CP8, 95% CI: 32,792-55,477), consistent with 69.2- and 28.9-fold rises in bacteria-killing antibodies, respectively; cLIA GMTs were 2064.4 (MntC, 95% CI: 1518.2-2807.0) and 3081.4 (ClfA, 95% CI: 2422.2-3920.0), consistent with 19.6- and 12.3-fold rises, respectively. Similar to cLIA results, ClfA FBI titers rose 11.0-fold (GMT: 672.2, 95% CI: 499.8-904.2). The vast majority of participants achieved the pre-defined biologically relevant thresholds: CP5: 100%; CP8: 97.9%, ClfA: 87.8%; and MntC 96.9%.

CONCLUSIONS

SA4Ag was safe, well tolerated, and rapidly induced high levels of bacteria-killing antibodies in healthy adults. A Phase 2B efficacy trial in adults (18-85years) undergoing elective spinal fusion is ongoing to assess SA4Ag's ability to prevent postoperative invasive surgical site and bloodstream infections caused by S. aureus. Clinicaltrials.gov Identifier: NCT02364596.

Immunogenicity, Safety, and Tolerability of Bivalent rLP2086 Meningococcal Group B Vaccine Administered Concomitantly With Diphtheria, Tetanus, and Acellular Pertussis and Inactivated Poliomyelitis Vaccines to Healthy Adolescents

KEY POINTS

Concomitant administration of bivalent rLP2086 (Trumenba [Pfizer, Inc] and diphtheria, tetanus, and acellular pertussis and inactivated poliovirus vaccine (DTaP/IPV) was immunologically noninferior to DTaP/IPV and saline and was safe and well tolerated. Bivalent rLP2086 elicited robust and broad bactericidal antibody responses to diverse Neisseria meningitidis serogroup B strains expressing antigens heterologous to vaccine antigens after 2 and 3 vaccinations.

BACKGROUND

Bivalent rLP2086, a Neisseria meningitidis serogroup B (MnB) vaccine (Trumenba [Pfizer, Inc]) recently approved in the United States to prevent invasive MnB disease in individuals aged 10-25 years, contains recombinant subfamily A and B factor H binding proteins (fHBPs). This study evaluated the coadministration of Repevax (diphtheria, tetanus, and acellular pertussis and inactivated poliovirus vaccine [DTaP/IPV]) (Sanofi Pasteur MSD, Ltd) and bivalent rLP2086.

METHODS

Healthy adolescents aged ≥11 to <19 years received bivalent rLP2086 + DTaP/IPV or saline + DTaP/IPV at month 0 and bivalent rLP2086 or saline at months 2 and 6. The primary end point was the proportion of participants in whom prespecified levels of antibodies to DTaP/IPV were achieved 1 month after DTaP/IPV administration. Immune responses to bivalent rLP2086 were measured with serum bactericidal assays using human complement (hSBAs) against 4 MnB test strains expressing fHBP subfamily A or B proteins different from the vaccine antigens.

RESULTS

Participants were randomly assigned to receive bivalent rLP2086 + DTaP/IPV (n = 373) or saline + DTaP/IPV (n = 376). Immune responses to DTaP/IPV in participants who received bivalent rLP2086 + DTaP/IPV were noninferior to those in participants who received saline + DTaP/IPV.The proportions of bivalent rLP2086 + DTaP/IPV recipients with prespecified seroprotective hSBA titers to the 4 MnB test strains were 55.5%-97.3% after vaccination 2 and 81.5%-100% after vaccination 3. The administration of bivalent rLP2086 was well tolerated and resulted in few serious adverse events.

CONCLUSIONS

Immune responses to DTaP/IPV administered with bivalent rLP2086 to adolescents were noninferior to DTaP/IPV administered alone. Bivalent rLP2086 was well tolerated and elicited substantial and broad bactericidal responses to diverse MnB strains in a high proportion of recipients after 2 vaccinations, and these responses were further enhanced after 3 vaccinations.ClinicalTrials.gov identifier NCT01323270.

Meningococcal Serogroup B Bivalent rLP2086 Vaccine Elicits Broad and Robust Serum Bactericidal Responses in Healthy Adolescents

BACKGROUND

Neisseria meningitidis serogroup B (MnB) is a leading cause of invasive meningococcal disease in adolescents and young adults. A recombinant factor H binding protein (fHBP) vaccine (Trumenba(®); bivalent rLP2086) was recently approved in the United States in individuals aged 10-25 years. Immunogenicity and safety of 2- or 3-dose schedules of bivalent rLP2086 were assessed in adolescents.

METHODS

Healthy adolescents (11 to <19 years) were randomized to 1 of 5 bivalent rLP2086 dosing regimens (0,1,6-month; 0,2,6-month; 0,2-month; 0,4-month; 0,6-month). Immunogenicity was assessed by serum bactericidal antibody assay using human complement (hSBA). Safety assessments included local and systemic reactions and adverse events.

RESULTS

Bivalent rLP2086 was immunogenic when administered as 2 or 3 doses; the most robust hSBA responses occurred with 3 doses. The proportion of subjects with hSBA titers ≥1:8 after 3 doses ranged from 91.7% to 95.0%, 98.9% to 99.4%, 88.4% to 89.0%, and 86.1% to 88.5% for MnB test strains expressing vaccine--heterologous fHBP variants A22, A56, B24, and B44, respectively. After 2 doses, responses ranged from 90.8% to 93.5%, 98.4% to 100%, 69.1% to 81.1%, and 70.1% to 77.5%. Geometric mean titers (GMTs) were highest among subjects receiving 3 doses and similar between the 2- and 3-dose regimens. After 2 doses, GMTs trended numerically higher among subjects with longer intervals between the first and second dose (6 months vs 2 and 4 months). Bivalent rLP2086 was well tolerated.

CONCLUSIONS

Bivalent rLP2086 was immunogenic and well tolerated when administered in 2 or 3 doses. Three doses yielded the most robust hSBA response rates against MnB strains expressing vaccine-heterologous subfamily B fHBPs.

Staphylococcus aureus: the current state of disease, pathophysiology and strategies for prevention

Staphylococcus aureus is both a commensal organism and also an important opportunistic human pathogen, causing a variety of community and hospital-associated pathologies, such as bacteremia-sepsis, endocarditis, pneumonia, osteomyelitis, arthritis and skin diseases. The resurgence of S. aureus during the last decade in many settings has been facilitated not only by bacterial antibiotic resistance mechanisms but also by the emergence of new S. aureus clonal types with increased expression of virulence factors and the capacity to neutralize the host immune response. Prevention of the spread of S. aureus infection relies on the use of contact precautions and adequate procedures for infection control that so far have not been fully effective. Prevention using a prophylactic vaccine would complement these processes, having the potential to bring additional, significant progress toward decreasing invasive disease due to S. aureus.

Approach to the Discovery, Development, and Evaluation of a Novel Neisseria meningitidis Serogroup B Vaccine

In this chapter, we describe a research and development pathway to identify and demonstrate the efficacy of a Neisseria meningitidis non-capsular vaccine, the recently licensed N. meningitidis serogroup B (MnB) vaccine, Trumenba(®). While other approaches have been followed in the identification of a MnB vaccine (Pizza et al. Science 287:1816-1820, 2000), the methods described here reflect the distinctive approach and experiences in discovering and developing Trumenba(®). In contrast to the development and licensure of polysaccharide-conjugate vaccines against meningococcal serotypes A, C, W, and Y, the development of a vaccine to produce broadly protective antibodies against meningococcal serogroup B has proved difficult, due to the antigenic mimicry of the serogroup B polysaccharide capsule, which is composed of polysialic acid structures similar to those expressed on human neuronal cells. Early development efforts for these vaccines failed because the MnB polysaccharide structures resemble autoantigens and thus were poorly immunogenic. The development of an MnB vaccine has therefore focused on non-polysaccharide approaches. It was critical to identify MnB cell surface-exposed antigens capable of inducing a protective response against diverse, circulating strains of invasive MnB to ensure global coverage. Once candidate antigens were identified, it was important to characterize antigenic variation and expression levels, and subsequently to assure that antigens were expressed broadly among diverse clinical isolates. Prior to the initiation of clinical trials in humans, candidate vaccine antigens were tested in functional immunogenicity assays and yielded responses that were correlated with protection from meningococcal disease. These functional immunogenicity assays (serum bactericidal assays using human complement, hSBAs) measure the titer of complement-dependent bactericidal antibodies in serum from immunized test animals using diverse clinical MnB isolates as targets. Following optimization of vaccine antigenic components based on hSBA responses in preclinical models, animal toxicology tests were performed. Initial clinical studies (Phase 1 and 2) subsequently provided data to support (1) safety and immunogenicity of the vaccine formulation, and (2) the dose and schedule. Phase 3 clinical trials were carried out in the target populations to provide the clinical confirmation of safety and efficacy required for vaccine licensure.

A randomized phase I study of the safety and immunogenicity of three ascending dose levels of a 3-antigen Staphylococcus aureus vaccine (SA3Ag) in healthy adults

BACKGROUND

Staphylococcus aureus is a common cause of healthcare-acquired morbidity and mortality and increased healthcare resource utilization. A prophylactic vaccine is being developed that may reduce this disease burden.

METHODS

Volunteers in good general health aged 50-85 (n=312) and 18-24 (n=96) years were randomized to receive a single intramuscular dose of one of three dose levels of a non-adjuvanted, 3-antigen S. aureus vaccine (SA3Ag) or placebo. SA3Ag antigens included capsular polysaccharides 5 and 8 (CP5 and CP8), each conjugated to cross-reactive material 197 (CRM197), and recombinant clumping factor A (ClfA). Safety, tolerability, and immunogenicity were evaluated.

RESULTS

At day 29 post-vaccination, robust immune responses were observed in both age cohorts at all three SA3Ag dose levels. In the primary analysis population, the 50- to 85-year age stratum, geometric mean-fold-rises in competitive Luminex(®) immunoassay antibody titers from baseline ranged from 29.2 to 83.7 (CP5), 14.1 to 31.0 (CP8), and 37.1 to 42.9 (ClfA), all (P<0.001) exceeding the pre-defined two-fold rise criteria. Similar rises in opsonophagocytic activity assay titers demonstrated functionality of the immune response. Most injection-site reactions were mild in severity and there were no substantial differences (SA3Ag vs. placebo) with regard to systemic or adverse events.

CONCLUSIONS

In this study of healthy adults aged 50-85 and 18-24 years, SA3Ag elicited a rapid and robust immune response and was well tolerated, with no notable safety concerns.

The discovery and development of a novel vaccine to protect against Neisseria meningitidis Serogroup B Disease

Vaccines have had a major impact on the reduction of many diseases globally. Vaccines targeted against invasive meningococcal disease (IMD) due to serogroups A, C, W, and Y are used to prevent these diseases. Until recently no vaccine had been identified that could confer broad protection against Neisseria meningitidis serogroup B (MnB). MnB causes IMD in the very young, adolescents and young adults and thus represents a significant unmet medical need. In this brief review, we describe the discovery and development of a vaccine that has the potential for broad protection against this devastating disease.

Potential impact of the bivalent rLP2806 vaccine on Neisseria meningitidis carriage and invasive serogroup B disease

Asymptomatic throat carriage of Neisseria meningitidis is common in healthy individuals. In unusual cases, the bacteria become invasive, resulting in life-threatening disease. Effective meningococcal serogroup B (MnB) vaccines should provide broad protection against disease-causing strains and may confer indirect protection by impacting carriage and subsequent transmission. Factor H binding proteins (fHBPs), components of MnB vaccines in development, are classified into two immunologically distinct subfamilies (A and B). fHBP variants of MnB strains carried by adolescents are similar to those detected in infants with MnB disease. A vaccine containing subfamily A and B fHBP variants elicited bactericidal antibody responses (titers ≥ 1:4) against MnB strains expressing fHBP variants common to carriage strains and strains that cause disease in adolescents and infants in 75–100% of adolescent study subjects. This suggests that the bivalent fHBP vaccine has the potential to provide protection against invasive MnB strains and interrupt meningococcal carriage, which may also reduce infant MnB disease.

Modulation of immunogenicity and allergenicity by controlling the number of immunostimulatory oligonucleotides linked to Amb a 1

BACKGROUND

Immunostimulatory DNA sequences (ISS) are potent immunomodulators that can drive T(H)1 responses to antigens or allergens. This effect can be dramatically enhanced by direct linkage of ISS to the protein.

OBJECTIVE

Evaluate the effects of the number of ISS bound to the major ragweed allergen Amb a 1 on immunogenicity and allergenicity.

METHODS

Immunogenicity in mice and allergenicity using PBMC or sera from subjects with ragweed allergy were assayed.

RESULTS

Both antibody induction in vivo and antibody recognition in vitro were highly sensitive to the number of ISSs linked. IgE recognition of Amb a 1 in competitive ELISA or histamine release assays was inhibited by ISS linkage and showed an inverse relationship to the number of ISSs bound. Type and magnitude of antibody induction in mice was also highly dependent on the number of ISS bound. At the highest ISS to protein ratios, antibody induction was very low. Moderate ISS to protein ratios induced high antibody responses in which IgG(2a) generally predominated. Low ISS to protein ratios produced the highest overall antibody responses in which IgG(1) predominated. In contrast, varied ISS to protein ratios did not affect T-cell responses. In both in vivo mouse studies and in vitro human PBMC studies, all ISS to protein ratios evaluated induced similar responses represented by high levels of IFN-gamma and low levels of T(H)2 cytokines.

CONCLUSION

Controlling the number of ISS bound to a protein allows manipulation of antibody recognition and induction while retaining the potent T(H)1 properties of an ISS-linked protein.

CLINICAL IMPLICATIONS

Immunostimulatory DNA sequence-linked Amb a 1 conjugate represents a safe, novel therapeutic approach for treating ragweed allergy.

Amb a 1-immunostimulatory oligodeoxynucleotide conjugate immunotherapy decreases the nasal inflammatory response

BACKGROUND

Amb a 1-immunostimulatory phosphorothioate oligonucleotide conjugate (AIC) is a novel immunotherapeutic compound consisting of purified Amb a 1 from short ragweed proteins covalently linked to an immunostimulatory phosphorothioate oligodeoxyribonucleotide. In sensitized animals AIC can stimulate an Amb a 1-specific T(H)1 response and decrease pulmonary reactivity to ragweed challenge. Clinical trials have documented reduced allergic response to AIC in comparison with licensed ragweed extract.

OBJECTIVES

We sought to determine the in vivo effect of short-course immunotherapy with AIC on eosinophilia and cytokine mRNA expression in the nasal mucosa of ragweed-sensitive patients.

METHODS

Ragweed-sensitive patients with allergic rhinitis were treated with 6 escalating doses of AIC (0.06-12 microg, n = 28) or placebo (n = 29) at weekly intervals immediately before the 2001 ragweed season. Symptom scores and medication use were recorded for the 2001 and 2002 ragweed seasons for all patients. A subset of patients (12 receiving AIC and 7 receiving placebo) consented to have nasal biopsy specimens taken before immunization and before and after the first ragweed season. The preseason and postseason biopsy specimens were taken 24 hours after ragweed allergen challenge and compared with the initial unchallenged biopsy specimen to assess cytokine and inflammatory cell responses by using immunocytochemistry and in situ hybridization.

RESULTS

AIC was safe and well tolerated by all patients. There was no difference between the AIC and placebo groups in the number of allergen-induced major basic protein-, IL-4-, IL-5-, or IFN-gamma-positive cells in the mucosa in the first weeks after AIC immunization. On rechallenge and rebiopsy after the end of the 2001 ragweed season, however, AIC-treated patients had a significantly reduced increase in eosinophils and IL-4 mRNA-positive cells and an increased number of IFN-gamma mRNA-positive cells compared with placebo-treated patients. No difference between treatment groups was observed in symptom scores or medication use during the first ragweed season. During the second ragweed season, however, there was a significant decrease in chest symptoms and a trend toward reduced nasal symptoms in the AIC-treated group.

CONCLUSION

Short-course immunotherapy with AIC can modify the response of nasal mucosa to allergen challenge by increasing T(H)1 cytokine production and decreasing T(H)2 cytokine production and eosinophilia. This modification was not immediate but was observed 4 to 5 months after completion of immunotherapy and seasonal ragweed-pollen exposure. The T-cell subset shift after immunization and seasonal exposure was followed by evidence of clinical efficacy in the second ragweed season without additional AIC immunizations.

Use of immunostimulatory sequence-containing oligonucleotides as topical therapy for genital herpes simplex virus type 2 infection

Synthetic oligonucleotides containing CpG motifs in specific sequence contexts have been shown to induce potent immune responses. We have evaluated mucosal administration of two immunostimulatory sequence (ISS)-containing phosphorothioate-stabilized oligonucleotides for antiherpetic efficacy in animal models. The ISS oligonucleotides, suspended in phosphate-buffered saline, were tested in mouse and guinea pig vaginal models of herpes simplex virus type 2 (HSV-2) infection. For comparison, groups of untreated, non-ISS oligonucleotide-treated, and acyclovir-treated animals also were monitored. The results indicated that vaginal epithelial application of ISS (up to 6 h after viral inoculation) with mice lethally challenged with HSV-2 delayed disease onset and reduced the number of animals that developed signs of disease (P = 0.003). ISS application significantly increased survival rates over those of controls (P = 0.0014). The ISS also impacted an established infection in the guinea pig model of HSV-2 disease. A single administration of ISS (21 days after viral inoculation) significantly reduced the frequency and severity of HSV-2 lesions compared to results with non-ISS oligonucleotide-treated and untreated guinea pigs (P < 0.01). HSV-2 is shed from the vaginal cavity of the guinea pig in the absence of lesions, similar to the case with humans. As an additional indication of ISS efficacy, the magnitude of viral shedding also was significantly reduced in ISS-treated animals (P < 0.001). These effects appeared to be immunologically mediated, since ISS had no direct effect on HSV-2 replication in vitro using standard plaque assays. These data suggest that ISS may be useful in the treatment and control of genital herpes in humans.

A randomized, controlled study in adults of the immunogenicity of a novel hepatitis B vaccine containing MF59 adjuvant

The safety and immunogenicity of a novel hepatitis B virus (HBV) vaccine containing recombinant PreS2 and S antigens combined with MF59 adjuvant (HBV/MF59) was evaluated in healthy adults (N=230) who were randomized to receive 2 or 3 immunizations of either the study vaccine or a licensed control vaccine (Recombivax HB). After a single immunization, 105 of 118 (89%) recipients of HBV/MF59 achieved protective serum levels of anti-HBs antibody (> 10 mIU/ml), compared with 13 of 110 (12%) recipients of licensed vaccine (P < 0.001). The geometric mean titer (GMT) after 2 doses of HBV/MF59 given 2 months apart (13,422 mIU/ml) was more than 5-fold higher than that following 3 doses of licensed vaccine given over 6 months (2,346 mIU/ml; P < 0.001). The GMT following 3 injections of HBV/MF59 (249,917 mIU/ml) was 100-fold higher than licensed vaccine (P < 0.001). Anti-PreS2 antibodies were elicited in over 90% of the subset of HBV/MF59 recipients tested. Both vaccines were well tolerated; transient, mild-to-moderate local inflammation was the major postinjection reaction.

Measles, mumps, rubella, and varicella combination vaccine: safety and immunogenicity alone and in combination with other vaccines given to children. Measles, Mumps, Rubella, Varicella Vaccine Study Group

Eight hundred and twelve children, 12 months to 3.5 years of age, were enrolled in two clinical studies to evaluate the safety and immunogenicity of a live, attenuated combination vaccine for measles, mumps, rubella, and varicella (MMRV). Children were enrolled in one of two randomized, multicenter studies, involving administration of (1) MMRV and placebo vs. measles, mumps, and rubella vaccine (M-M-R(II)) and varicella-zoster virus vaccine (VARIVAX), given at separate anatomic sites at the same office visit; or (2) MMRV, DTaP (diphtheria, tetanus, and acellular pertussis vaccine) and OPV (oral polio vaccine) vs. M-M-R(II), DTaP, and OPV, with VARIVAX given 6 weeks later. All vaccine regimens were generally well tolerated. More than 95% of vaccinees seroconverted for measles, mumps, rubella, and varicella, regardless of the vaccine or regimen used. In each study, the level of antibody titer to varicella virus was significantly lower in vaccinees receiving MMRV than in those who received VARIVAX in a separate syringe.

Evaluation of inhA gene and catalase-peroxidase gene among isoniazid-sensitive and resistant Mycobacterium tuberculosis isolates

The katG gene and the inhA gene of 30 INH-resistant (INH-R) and 28 INH-sensitive (INH-S) isolates of M. tuberculosis from Haiti and Maryland were analysed by PCR to establish the presence and frequency of two postulated mechanisms of INH-resistance, total katG gene deletion and inhA Ser94 to Ala94 amino acid substitution. Only two of 30 INH-R isolates (3%) appear to have total katG gene deletions. All 28 INH-S isolates (100%) produced a PCR product at both the 5' and the 3' ends of the katG gene. Gene deletion of katG is a rare mechanism of INH resistance. Allele specific oligonucleotide hybridisation analysis of the inhA PCR products from the same 58 isolates revealed no mutation at amino acid 94 or directly surrounding it. Other inhA gene mutations may be responsible for INH resistance in M. tuberculosis. Diagnostic strategies using katG gene deletion or inhA Ser94 mutations would fail to detect almost all INH-R isolates.

The nonstructural glycoprotein of rotavirus affects intracellular calcium levels

Rotavirus infection of monkey kidney cells has been reported to result in a significant increase in the concentration of intracellular calcium. This increase in intracellular calcium was associated with viral protein synthesis and cytopathic effects in infected cells. We tested the effect of individual rotavirus proteins on intracellular calcium concentrations in insect Spodoptera frugiperda (Sf9) cells. Insect cells were infected with wild-type baculovirus or baculovirus recombinants that contained an individual rotavirus gene. The cells were harvested at different times postinfection, and the intracellular calcium concentration was measured by using fura-2 as a fluorescent calcium indicator. We found that the concentration of intracellular calcium was increased nearly fivefold in infected Sf9 cells that expressed the nonstructural glycoprotein (NSP4) of group A rotavirus, and this increase in intracellular calcium concentration coincided with NSP4 expression. A similar result was observed in insect cells expressing NSP4 from a group B rotavirus, suggesting the conservation of this function among rotavirus groups. Expression of the other 10 rotavirus proteins or of wild-type baculovirus proteins in Sf9 cells did not significantly increase intracellular calcium levels. These results suggest that the nonstructural glycoprotein NSP4 is responsible for the increase in cytosolic calcium observed in rotavirus-infected cells.

Detection of rotaviruses in the day care environment by reverse transcriptase polymerase chain reaction

Group A rotavirus is an important cause of morbidity among infants and toddlers in day care centers. Transmission by the fecal-oral route is well established, but fomites and environmental surfaces may also play an important role in transmission. A highly sensitive polymerase chain reaction (PCR) assay was used to detect rotavirus RNA in day care environments. Areas sampled included floors, diaper change areas, toy balls, and other surfaces. In two centers undergoing outbreaks of rotavirus, 7 (39%) of 18 toy balls had detectable rotavirus as did 8 (21%) of 39 swabs from environmental surfaces. By comparison, only 1 (5%) of 21 toy balls and 1 (2%) of 44 environmental surface swabs had detectable rotavirus in centers without rotavirus outbreaks (P = .0001). Thus, rotaviruses are highly prevalent in day care centers during outbreaks of diarrhea. The monitoring of environments by sensitive nucleic acid amplification techniques may lead to strategies for the diminution of disease transmission within the day care environment.

Use of ciprofloxacin in an infant with ventriculitis

Ciprofloxacin was used successfully in a neonate with ventriculitis caused by a multiply resistant strain of Enterobacter cloacae. Limited pharmacokinetic data indicated that adequate concentrations of drug could be attained in cerebrospinal fluid.

Improved detection of rotavirus shedding by polymerase chain reaction

To improve identification of children excreting rotavirus a method for the amplification of rotavirus RNA by the polymerase chain reaction (PCR) was developed. The assay was compared with a solid-phase enzyme immunoassay in the detection of rotavirus shedding by infants in hospital during the winter peak of rotavirus infections. Forty children were studied in an intermediate care unit after transfer from intensive care units. Only two were admitted primarily because of diarrhoea; the other thirty-eight were admitted for management of various other disorders. Rotavirus shedding was detected by enzyme immunoassay in twenty of the infants, and nine of these (aged 1 week to 8 months) remained in hospital for more than 5 days after the initial detection of rotavirus and could be studied long term. Of 103 faecal samples from the nine infants, 60 (58%) contained rotavirus RNA detected by reverse-transcriptase (RT)/PCR, whereas only 37 (36%) were positive for rotavirus antigen by the immunoassay (chi 2 = 10.3, p less than 0.002). The geometric mean time of rotavirus shedding was 9.5 (range 1-19) days as detected by RT/PCR and 5.7 (range 1-17) days by the immunoassay (p less than 0.018). In five of the nine children, RT/PCR detected rotavirus shedding for 2-7 days longer than the immunoassay and in four children RT/PCR was positive 1 or more days before rotavirus antigen was detected. Further studies should attempt to find out whether infected infants are capable of spreading wild-type virus during periods when they are not shedding antigen as detectable by enzyme immunoassay.

Immunoglobulins and other modalities for the prevention and treatment of enteric viral infections

Viral infections of the gastrointestinal tract constitute a major health problem during the first years of life. In addition to causing acute diarrhea, rotaviruses and other enteric viruses may be involved in the pathogenesis of necrotizing enterocolitis and other neonatal enteric diseases. There are several potential methods for the prevention and treatment of gastrointestinal viral infections. Antiviral immune globulins, administered by the parenteral or oral route, might prove useful for the inhibition of intestinal viral replication. Alternatively, specific glycoprotein inhibitors of viral-cell binding might be used to prevent the productive infection of intestinal epithelial cells. In addition, since many enteric viruses require proteolytic enzymes for protein cleavage, protease inhibitors may prove to be effective agents for the inhibition of intestinal viral replication. At this point in time, these methods have proven useful for the inhibition of rotavirus infection in experimental animals. The successful application of these and other methods for the prevention of enteric infections in humans might substantially reduce the morbidity and mortality associated with enteric diseases.

Removal of inhibitory substances from human fecal specimens for detection of group A rotaviruses by reverse transcriptase and polymerase chain reactions

A method was developed for the purification of rotavirus RNA from fecal extracts in order to permit the sensitive identification of group A rotavirus in fecal specimens by the polymerase chain reaction. Sequential reactions with reverse transcriptase and Taq polymerase with directed primers from rotavirus gene 6 yielded characteristic 259-base-pair fragments that were then visualized by silver stain on a polyacrylamide gel. As few as 500 genomic copies of purified rotavirus RNA could be detected in this manner. However, when the method was applied to fecal samples with added rotavirus virions, inhibition was noted in many of the fecal extracts which were tested. The inhibition could be reversed by dilution of the fecal extract, but sensitivity was also reduced by a corresponding dilutional factor. The inhibition was quantitatively removed by an added step in the extraction process that utilized chromatographic cellulose fiber powder (CF11 powder) to purify the rotavirus RNA during a series of rapid washing and elution steps. After CF11 purification, rotavirus RNA could be detected in experimental fecal samples at dilutions 1,000- to 10,000-fold beyond the detection limits of standard techniques such as enzyme immunoassay and the direct visualization of RNA following polyacrylamide gel electrophoresis. Furthermore, following purification by CF11, rotavirus RNA could be detected in all of seven enzyme-linked immunosorbent assay-positive fecal samples obtained from a child with rotavirus gastroenteritis; when CF11 purification was not performed, rotavirus RNA could be detected in only four of these samples, even after the removal of inhibitors by dilution of the extracts. Large-scale identification of rotavirus in fecal specimens may be possible by use of CF11 purification of viral RNA prior to sequential reactions with reverse transcriptase and Taq polymerase in a modified polymerase chain reaction.

Purification and characterization of adult diarrhea rotavirus: identification of viral structural proteins

Adult diarrhea rotavirus (ADRV) is a newly identified strain of noncultivable human group B rotavirus that has been epidemic in the People's Republic of China since 1982. We have used sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western (immuno-) blot analysis to examine the viral proteins present in the outer and inner capsids of ADRV and compared these with the proteins of a group A rotavirus, SA11. EDTA treatment of double-shelled virions removed the outer capsid and resulted in the loss of three polypeptides of 64, 61, and 41, kilodaltons (kDa). Endo-beta-N-acetylglucosaminidase H digestion of double-shelled virions identified the 41-kDa polypeptide as a glycoprotein. CaCl2 treatment of single-shelled particles removed the inner capsid and resulted in the loss of one polypeptide with a molecular mass of 47 kDa. The remaining core particle had two major structural proteins of 136 and 113 kDa. All of the proteins visualized on sodium dodecyl sulfate-polyacrylamide gel electrophoresis were antigenic by Western blot analysis when probed with convalescent-phase human and animal antisera. A 47-kDa polypeptide was most abundant and was strongly immunoreactive with human sera, animal sera raised against ADRV and against other group B animal rotaviruses (infectious diarrhea of infant rat virus, bovine and porcine group B rotavirus, and bovine enteric syncytial virus) and a monoclonal antibody prepared against infectious diarrhea of infant rat virus. This 47-kDa inner capsid polypeptide contains a common group B antigen and is similar to the VP6 of the group A rotaviruses. Human convalescent-phase sera also responded to a 41-kDa polypeptide of the outer capsid that seems similar to the VP7 of group A rotavirus. Other polypeptides have been given tentative designations on the basis of similarities to the control preparation of SA11, including a 136-kDa polypeptide designated VP1, a 113-kDa polypeptide designated VP2, 64- and 61-kDa polypeptides designated VP5 and VP5a, and several proteins in the 110- to 72-kDa range that may be VP3, VP4, or related proteins. The lack of cross-reactivity on Western blots between antisera to group A versus group B rotaviruses confirmed that these viruses are antigenically quite distinct.

Identification of a group-reactive epitope of group B rotaviruses recognized by monoclonal antibody and application to the development of a sensitive immunoassay for viral characterization

Group B rotaviruses (GBRs) are fastidious agents which cause enteric disease in humans and a number of other animal species. Detailed study of the role of GBRs in human disease has been hampered by the lack of immunoreagents suitable for large-scale studies. We developed a monoclonal antibody which recognizes a group-reactive antigen contained in a number of strains of GBRs. When utilized in conjunction with a hyperimmune guinea pig antiserum to GBR, this monoclonal antibody can be used in an enzyme immunoassay system to detect a wide range of GBRs. Alternatively, this monoclonal antibody can be combined with sera obtained from GBR-infected animals to devise assays which are largely specific for the homologous strain of GBR. Reactivity was not noted in either system with strains of group A or group C rotaviruses or with other members of the family Reoviridae. These results indicate that GBRs contain both group-reactive and species-specific antigens which are distinct from those found in group A rotaviruses. The availability of well-defined immunoreagents will facilitate detailed studies of GBR infections in humans and animals.

Specificity of dot hybridization assay in the presence of rRNA for detection of rotaviruses in clinical specimens

Nucleic acid hybridization is used to identify viral genomic sequences in clinical and environmental samples. However, RNA virus genomes have been reported to hybridize to mammalian rRNA from uninfected cells under stringent conditions, and caution has therefore been advised in the use of nucleic acid probes for detection of RNA viruses. To evaluate the effect of rRNA on a diagnostic assay for an RNA virus, we tested the specificity of a rotavirus dot hybridization assay with clinical specimens which contained eucaryotic rRNA. The cDNA probe used in this assay contained sequences complementary to all 11 rotavirus genes. Preliminary experiments indicated that hybridization between rRNA and the cDNA probe occurred only with greater than 50 ng of rRNA, and this interaction was easily distinguished from the hybridization of the rotavirus probe with homologous or heterologous strains of the same rotavirus group. When 95 clinical specimens were tested, the rotavirus dot hybridization assay had a specificity of 98.8%. The predictive value of a negative test was 94.2%, although nearly all of the specimens contained rRNA and also reacted with an rRNA probe. Although the specificity of all dot hybridization assays should be individually evaluated, we conclude that our dot hybridization assay for rotaviruses is highly specific even in the presence of quantities of rRNA that may be anticipated in extracts of fecal specimens.

Self-contained enzymic membrane immunoassay for detection of rotavirus antigen in clinical samples

A self-contained enzymic membrane immunoassay (SCEMIA) system has been developed for the detection of viral antigens in clinical samples. The assay system makes use of antiviral antibodies bound to a nylon membrane, a flow-through washing procedure, and a clearly visible endpoint of the enzymic reaction. A SCEMIA system with antibodies against rotavirus detected rotavirus antigen, within 15 min, in all faecal samples from children with gastroenteritis that were positive for antigen in a standard microplate enzyme immunoassay, which took 4 h to complete. In addition, the SCEMIA could detect rotavirus in faecal samples collected from infected individuals both before and after antigen could be detected by a standard immunoassay system. Rotavirus antigen was not detectable in control children who did not have evidence of rotavirus infection. SCEMIA systems are an accurate, rapid, and inexpensive means for the practical diagnosis of viral infections in human beings.

Homotypic and heterotypic antibodies for prevention of experimental rotavirus gastroenteritis

We investigated the abilities of homologous and heterologous antibody preparations to neutralize murine rotavirus in a mouse model of rotavirus infection. We found that incubation of virus with murine sera obtained from animals experimentally infected with the homologous epizootic diarrhea of infant mice strain of rotavirus resulted in inability of the virus to cause symptomatic disease in infant mice. Sera from nonimmune mice and mice infected or immunized with a heterotypic strain of rotavirus did not effectively neutralize virus in this system. On the other hand, neutralization was noted after incubation of virus with a number of immunoglobulins from other animal and human sources. The neutralizing activity of the preparations in the murine model correlated partially, but not completely, with the level of in vitro neutralizing antibody to the murine strain of rotavirus measured in a tissue culture system. In most cases, asymptomatic infection after feeding of the virus and the antibody preparation resulted in subsequent generation of an active immune response in infected animals.

Genetic and antigenic relatedness of human and animal strains of antigenically distinct rotaviruses

We used nucleic-acid hybridization and enzymatic and immunofluorescence assay to examine the relatedness of human and animal strains of antigenically distinct rotaviruses (ADRVs). ADRVs isolated from rats and humans in Baltimore, Maryland, were shown to be closely related to bovine and porcine strains of group B rotavirus. A human group B rotavirus associated with epidemics of gastroenteritis in China was also found to share antigenic determinants and genome sequence homology with ADRVs passaged in rats in the United States. Closely related strains of group B rotavirus thus appear to infect human and animal populations in widely separated geographic areas.

Centrifugation-augmented solid-phase immunoassay (CASPIA) for the rapid diagnosis of infectious diseases

We have devised centrifugation-augmented solid-phase immunoassays (CASPIAs) for the detection of microbial pathogens in human body fluids. The CASPIA format combines several features of latex agglutination and solid-phase immunoassay systems to produce an assay system that is inexpensive and simple to perform. We found that CASPIA systems for the detection of rotaviral, group A streptococcal, and Haemophilus influenzae type b antigens were significantly more sensitive than latex agglutination assays and at least as sensitive as enzyme immunoassay systems using analogous reagents. Because CASPIA reactions could either be read macroscopically, recorded with a standard office photocopying device, or quantitated by means of a microplate colorimeter, the assays were applicable under a wide range of clinical and laboratory conditions.