RELATION OF A STREPTOCOCCUS TO EPIDEMIC POLIOMYELITIS—Studies in Etiology,Diagnosis and Specific Treatment

The production in 1915 of herpes zoster or “posterior” poliomyelitis in animals with a streptococcus led to further research on the etiologic importance of streptococci in “anterior” poliomyelitis.A specific streptococcus was demonstrated consistently in persons with poliomyelitis and in well persons having contact with them or merely inhabiting an area in which poliomyelitis was epidemic. That the organism was not present in areas remote from contact with the disease was likewise demonstrated.The streptococcus has been isolated from filtrates of poliomyelitis virus and from the tissues and exudates which harbor the virus. It appears in the spinal fluid in the preparalytic stage of poliomyelitis and disappears from the spinal fluid during the severe stage of the disease.Antibody and antigen prepared from the streptococcus were used to determine the presence of antigen and antibody indicative of streptococcal infection in many patients with poliomyelitis and in well persons. The intensity of reaction indicating specific streptococcal antigen was directly proportional to the degree of paralysis in patients; the reaction was greater in persons whose age, sex and previous isolation from the disease would normally indicate greater susceptibility. The test for antibody gave opposite results.Specific agglutinins for the streptococcus and neutralizing antibody for the virus were present consistently in the serum of persons and monkeys during recovery from poliomyelitis.Virus produced in vitro from the associated streptococcus caused all the clinical and pathologic features of poliomyelitis in monkeys inoculated with it, and the animals that recovered from the disease thus induced were proved to be immune thereafter to the natural virus.Antistreptococcic serum prepared in horses was used to treat poliomyelitis. In a group of monkeys inoculated with the virus of the disease, 6 per cent of those receiving the serum before inoculation died of the disease; of the control group, 82 per cent. In a series of poliomyelitis patients treated with the serum the mortality rate was 8 per cent; in a control series, 21 per cent. In a series treated in all stages of the disease by the author, 10 per cent died; of those who did not receive the serum, 25 per cent.An antibody has been prepared from the streptococcus which appears to prevent paralysis and otherwise mitigate poliomyelitis and to provide immunization from the disease.The conclusion is reached that the virus of poliomyelitis is a form of the specific streptococcus, which is the agent in primary infections and in the development of the immunizing antibody.     

Reinvestigating the Role of IgM in Rabies Virus Postexposure Vaccination

B cells secreting IgG antibodies, but not IgM, are thought to be solely responsible for vaccine-induced protection against rabies virus (RABV) infections in postexposure settings. In this report, we reinvestigated the potential for IgM to mediate protection in a mouse model of RABV vaccination. Immunocompetent mice immunized with an experimental live replication-deficient RABV-based vaccine produced virus neutralizing antibodies (VNAs) within 3 days of vaccination. However, mice unable to produce soluble IgM (sIgM^−/−) did not produce VNAs until 7 days postimmunization. Furthermore, sIgM^−/− mice were not protected against RABV infection when challenged 3 days postimmunization, while all wild-type mice survived challenge. Consistent with the lack of protection against pathogenic RABV challenge, approximately 50- to 100-fold higher viral loads of challenge virus were detected in the muscle, spinal cord, and brain of immunized sIgM^−/− mice compared to control mice. In addition, IgG antibody titers in vaccinated wild-type and sIgM^−/− mice were similar at all time points postimmunization, suggesting that protection against RABV challenge is due to the direct effects of IgM and not the influence of IgM on the development of effective IgG antibody titers. In all, early vaccine-induced IgM can limit dissemination of pathogenic RABV to the central nervous system and mediate protection against pathogenic RABV challenge. Considering the importance for the rapid induction of VNAs to protect against RABV infections in postexposure prophylaxis settings, these findings may help guide the development of a single-dose human rabies vaccine.     

Vaccines beyond antibodies: Spurred by pandemic research,are T‐cell vaccines moving closer to reality?

Lessons learned from the vaccines against SARS‐CoV‐2 has encouraged research and vaccine development aimed at mustering strong T cell responses against the pathogen. Subject Categories: Microbiology, Virology & Host Pathogen Interaction, Pharmacology & Drug Discovery

The new vaccines against SARS‐CoV‐2 elicited strong antibody responses in initial trials, which encouraged optimism amongst immunologists and public health experts who expected good efficacy. “With viral infections, it is almost unheard of to have a prophylactic vaccine that doesn’t work ultimately by generating neutralising antibody responses”, explained immunologist Kingston Mills at Trinity College Dublin in Ireland. However, the antibody response is not the whole story. “Efforts to explain how immunity is working against viruses to the general public has forced everyone to try to make things so simple that now what is left is a ridiculous oversimplified picture of the vertebrate immune system”, commented Antonio Bertoletti, infectious disease scientist at Duke‐National University of Singapore. In fact, there is increasing research focus on the role of T cells in mediating the cellular response to infections and how to stimulate these cells through vaccines.Antibodies work by recognising and attaching to surface structures of a virus or bacterium, which prevents the pathogen from infecting its target cells and mark it for destruction by other immune cells. However, pathogens can escape the antibody response via mutations that decrease the efficiency of antibodies from infection or vaccination. “You will still potentially get infected if you’re vaccinated, because the antibody response is not as strong as it was”, explained immunologist Luke O’Neill at Trinity College Dublin, Ireland. “But then the T cells will kick in and stop the virus when it is inside cells”. Simply put, antibodies tend to prevent infection, while T cells combat infection and illness. Specifically, CD4 helper T cells primarily encourage B cells to generate antibodies whereas CD8 “killer” T cells eliminate cancerous and virally infected cells.     

Antiviral antibodies are necessary to prevent cytotoxic T-lymphocyte escape in mice infected with a coronavirus

Mutation within virus-derived CD8 T-cell epitopes can effectively abrogate cytotoxic T-lymphocyte (CTL) recognition and impede virus clearance in infected hosts. These so-called “CTL escape variant viruses” are commonly selected during persistent infections and are associated with rapid disease progression and increased disease severity. Herein, we tested whether antiviral antibody-mediated suppression of virus replication and subsequent virus clearance were necessary for preventing CTL escape in coronavirus-infected mice. We found that compared to wild-type mice, B-cell-deficient mice did not efficiently clear infectious virus, uniformly developed clinical disease, and harbored CTL escape variant viruses. These data directly demonstrate a critical role for antiviral antibody in protecting from the selective outgrowth of CTL escape variant viruses.     

B-Cell Responses to Human Bocaviruses 1–4: New Insights from a Childhood Follow-Up Study

Human bocaviruses (HBoVs) 1–4 are recently discovered, antigenically similar parvoviruses. We examined the hypothesis that the antigenic similarity of these viruses could give rise to clinically and diagnostically important immunological interactions. IgG and IgM EIAs as well as qPCR were used to study ~2000 sera collected from infancy to early adolescence at 3–6-month intervals from 109 children whose symptoms were recorded. We found that HBoV1-4-specific seroprevalences at age 6 years were 80%, 48%, 10%, and 0%, respectively. HBoV1 infections resulted in significantly weaker IgG responses among children who had pre-existing HBoV2 IgG, and vice versa. Furthermore, we documented a complete absence of virus type-specific immune responses in six viremic children who had pre-existing IgG for another bocavirus, indicating that not all HBoV infections can be diagnosed serologically. Our results strongly indicate that interactions between consecutive HBoV infections affect HBoV immunity via a phenomenon called “original antigenic sin”, cross-protection, or both; however, without evident clinical consequences but with important ramifications for the serodiagnosis of HBoV infections. Serological data is likely to underestimate human exposure to these viruses.     

Correlation between Dengue-Specific Neutralizing Antibodies and Serum Avidity in Primary and Secondary Dengue Virus 3 Natural Infections in Humans

Although heterotypic secondary infection with dengue virus (DENV) is associated with severe disease, the majority of secondary infections are mild or asymptomatic. The mechanisms of antibody-mediated protection are poorly understood. In 2010, 108 DENV3-positive cases were enrolled in a pediatric hospital-based study in Managua, Nicaragua, with 61 primary and 47 secondary infections. We analyzed DENV-specific neutralization titers (NT₅₀), IgM and IgG avidity, and antibody titer in serum samples collected during acute and convalescent phases and 3, 6, and 18 months post-infection. NT₅₀ titers peaked at convalescence and decreased thereafter. IgG avidity to DENV3 significantly increased between convalescent and 3-month time-points in primary DENV infections and between the acute and convalescent phase in secondary DENV infections. While avidity to DENV2, a likely previous infecting serotype, was initially higher than avidity to DENV3 in secondary DENV infections, the opposite relation was observed 3–18 months post-infection. We found significant correlations between IgM avidity and NT₅₀ in acute primary cases and between IgG avidity and NT₅₀ in secondary DENV infections. In summary, our findings indicate that IgM antibodies likely play a role in early control of DENV infections. IgG serum avidity to DENV, analyzed for the first time in longitudinal samples, switches from targeting mainly cross-reactive serotype(s) to the current infecting serotype over time. Finally, serum avidity correlates with neutralization capacity.     

Herpes Simplex Virus-Specific IgM,IgA and IgG Subclass Antibody Responses in Primary and Nonprimary Genital Herpes Patients

To clarify the humoral immunity in herpes simplex virus (HSV) infection, HSV-specific IgM, IgA and IgG subclass antibody responses were studied in patients with genital herpes: 17 primary, 13 recurrent and 6 nonprimary first episode. A total of 181 serum samples serially collected from the patients, 5 per patient until 213 days after the onset of disease (on average), were analyzed by an enzyme-linked immunosorbent assay. IgGl, IgG3 and IgA were detected in all patients with primary and nonprimary infections, whereas IgG4 was detected in 74% of only those with nonprimary infections and IgG2 was detected in none. IgM was detected in 100% of the patients with primary infections, but also in 68% of those with nonprimary infections. IgA showed a peak similar to that of IgM in patients with primary infections. No significant difference was observed in the detection rate or pattern of antibody responses between the recurrent and nonprimary first episode infections, nor between the HSV-1 and HSV-2 infections. These findings may be useful to improve the diagnostic potential of HSV serology.     

Impaired Antibody Response Causes Persistence of Prototypic T Cell–Contained Virus

CD8 T cells are recognized key players in control of persistent virus infections, but increasing evidence suggests that assistance from other immune mediators is also needed. Here, we investigated whether specific antibody responses contribute to control of lymphocytic choriomeningitis virus (LCMV), a prototypic mouse model of systemic persistent infection. Mice expressing transgenic B cell receptors of LCMV-unrelated specificity, and mice unable to produce soluble immunoglobulin M (IgM) exhibited protracted viremia or failed to resolve LCMV. Virus control depended on immunoglobulin class switch, but neither on complement cascades nor on Fc receptor γ chain or Fc γ receptor IIB. Cessation of viremia concurred with the emergence of viral envelope-specific antibodies, rather than with neutralizing serum activity, and even early nonneutralizing IgM impeded viral persistence. This important role for virus-specific antibodies may be similarly underappreciated in other primarily T cell–controlled infections such as HIV and hepatitis C virus, and we suggest this contribution of antibodies be given consideration in future strategies for vaccination and immunotherapy.     

Functions of the two particles of tobacco rattle virus

Functions of long and short particles of five different tobacco rattle virus (TRV) systems were studied by complementation experiments with the corresponding long and short species of ribonucleic acid (RNA). The progeny of long RNA species alone was proteinless or “free” infectious long RNA, whereas short RNA species alone did not replicate by themselves but appeared to be dependent on long RNA for replication. When both types of RNA derived from the same isolate were inoculated together, particulate virus with long and short particles was produced in more than 50% of the resulting primary infections. These virus systems obtained by homologous complementation resembled the parent isolates in all their characteristics. In addition, heterologous complementation tests were performed with long and short RNA, each derived from another isolate. Heterologous interaction could be observed in only 2 out of 20 possible combinations. As a result, two “mixed” TRV systems with respect to their particle length distributions were obtained, since their long and short particles resembled the ones from the other isolate. The symptoms produced by these mixed viruses were determined by the corresponding long RNA and appeared not to be influenced by the heterologous short one. However, the protein coat of both particles of the “mixed” viruses was specified by the corresponding noninfectious short RNA. Therefore, TRV is a system of at least two functionally defective and mutually complementing components which appear to be specialized in early and late functions.     

Estimating the Life Course of Influenza A(H3N2) Antibody Responses from Cross-Sectional Data

The immunity of a host population against specific influenza A strains can influence a number of important biological processes, from the emergence of new virus strains to the effectiveness of vaccination programmes. However, the development of an individual’s long-lived antibody response to influenza A over the course of a lifetime remains poorly understood. Accurately describing this immunological process requires a fundamental understanding of how the mechanisms of boosting and cross-reactivity respond to repeated infections. Establishing the contribution of such mechanisms to antibody titres remains challenging because the aggregate effect of immune responses over a lifetime are rarely observed directly. To uncover the aggregate effect of multiple influenza infections, we developed a mechanistic model capturing both past infections and subsequent antibody responses. We estimated parameters of the model using cross-sectional antibody titres to nine different strains spanning 40 years of circulation of influenza A(H3N2) in southern China. We found that “antigenic seniority” and quickly decaying cross-reactivity were important components of the immune response, suggesting that the order in which individuals were infected with influenza strains shaped observed neutralisation titres to a particular virus. We also obtained estimates of the frequency and age distribution of influenza infection, which indicate that although infections became less frequent as individuals progressed through childhood and young adulthood, they occurred at similar rates for individuals above age 30 y. By establishing what are likely to be important mechanisms driving epochal trends in population immunity, we also identified key directions for future studies. In particular, our results highlight the need for longitudinal samples that are tested against multiple historical strains. This could lead to a better understanding of how, over the course of a lifetime, fast, transient antibody dynamics combine with the longer-term immune responses considered here.     

The new ParaDIgm: IgM from bench to clinic: November 15–16, 2011, Frankfurt,Germany

The inaugural IgM event entitled “The new ParaDIgm: IgM from bench to clinic” brought together the increasingly active and growing IgM antibody community to discuss recent advances and challenges facing the discovery and development of IgM antibody therapies and technologies. Researchers, clinicians and biomanufacturing experts delivered 21 talks on the basic science and isolation of IgM, upstream and downstream development, and formulation and clinical development of the molecules. Participants networked around topics aimed at exploring the full potential of IgM antibodies. The meeting was held at DECHEMA Gesellschaft für Chemische Technik und Biotechnologie e. V. (Society for Chemical Engineering and Biotechnology), a non-profit scientific and technical society based in Frankfurt am Main, Germany. The meeting was sponsored by Patrys, Laureate Biopharma, Bio-Rad Laboratories, BIA Separations, Percivia and the Bio Affinity Company (BAC). The second New ParaDIgm: IgM from bench to clinic meeting, will be held on April 23–24, 2013 in Frankfurt, Germany.     

Rapid production of neutralizing antibody leads to transient hepadnavirus infection

Hepatitis B virus (HBV) frequently causes transient infections in adults but chronic infections in infants. The basis of these age-related outcomes is not known. Infection of ducks with duck hepatitis B virus (DHBV) displays a similar dependence of outcome on the age of the host at the time of infection. In this study we compared the infection of ducks at 3 days and 3 weeks of age. We found that the efficiency of infection of hepatocytes by virus in the inoculum was similar between the two age groups but that spread of the infection throughout the liver was severely inhibited in the 3-week-old-old ducks, while a rapid spread of the infection was observed in 3-day-old ducklings. Inhibition of virus spread was accompanied by the appearance in the serum of virus neutralizing activity, as assayed by blocking of infection of primary hepatocyte cultures. Neutralizing activity appeared as early as 1 or 2 days postinfection and increased during the next 2 weeks. Depletion of immunoglobulins from serum eliminated the neutralizing activity. The specific depletion of IgM indicated that IgM appeared as the dominant fraction of neutralizing antibody in the first 2 days postinfection, but declined from day 3 on while IgG antibody rose. We conclude that excess neutralizing antibody arising rapidly in birds inoculated at 3 weeks of age but not in newly hatched ducks prevented secondary cycles of infection, resulting in a limited infection in the liver and contributing to the eventual transient outcome of the infection.     

Inhibition of Marburg Virus Budding by Nonneutralizing Antibodies to the Envelope Glycoprotein

The envelope glycoprotein (GP) of Marburg virus (MARV) and Ebola virus (EBOV) is responsible for virus entry into host cells and is known as the only target of neutralizing antibodies. While knowledge about EBOV-neutralizing antibodies and the mechanism for the neutralization of infectivity is being accumulated gradually, little is known about antibodies that can efficiently regulate MARV infectivity. Here we show that MARV GP-specific monoclonal antibodies AGP127-8 (IgG1) and MGP72-17 (IgM), which do not inhibit the GP-mediated entry of MARV into host cells, drastically reduced the budding and release of progeny viruses from infected cells. These antibodies similarly inhibited the formation of virus-like particles (VLPs) consisting of GP, the viral matrix protein, and nucleoprotein, whereas the Fab fragment of AGP127-8 showed no inhibitory effect. Morphological analyses revealed that filamentous VLPs were bunched on the surface of VLP-producing cells cultured in the presence of the antibodies. These results demonstrate a novel mechanism of the antibody-mediated inhibition of MARV budding, in which antibodies arrest unformed virus particles on the cell surface. Our data lead to the idea that such antibodies, like classical neutralizing antibodies, contribute to protective immunity against MARV and that the “classical” neutralizing activity is not the only indicator of a protective antibody that may be available for prophylactic and therapeutic use.     

LEUKOCYTES IN “VIRUS X” INFECTION

Study of blood taken from patients with the recent “Virus X” “flu” syndrome showed slight leukopenia and the presence of abnormal lymphocytes, the most characteristic of which were those showing basophilic cytoplasm. These cells, often called Turk cells, and which the authors have termed “toxic” lymphocytes, are similar to those found in other virus infections.     

Antibody responses to early antigens of varicella-zoster virus (VZV) during varicella and zoster

The antibody responses to membrane and early antigens and thymidine kinase of varicella-zoster virus (VZV) were studied in sera during both varicella and zoster by a test with fluorescent antibody to membrane antigen (FAMA), staining the biochemically transformed cells by the immunofluorescent technique and neutralization of virus-specific thymidine kinase activity, respectively. Similar increases in FAMA antibody titers were demonstrated in sera from patients with varicella and zoster. IgM was detected in both groups, but appeared earlier during varicella than during zoster. Furthermore, the antibody titers to early antigens and virus-specific thymidine kinase were higher in patients with zoster than in those with varicella. These data suggest that different types of antibody responses occur during varicella and zoster.     

Dengue Virus Neutralizing Antibody Levels Associated with Protection from Infection in Thai Cluster Studies

Background

Long-term homologous and temporary heterologous protection from dengue virus (DENV) infection may be mediated by neutralizing antibodies. However, neutralizing antibody titers (NTs) have not been clearly associated with protection from infection.

Methodology/Principal Findings

Data from two geographic cluster studies conducted in Kamphaeng Phet, Thailand were used for this analysis. In the first study (2004–2007), cluster investigations of 100-meter radius were triggered by DENV-infected index cases from a concurrent prospective cohort. Subjects between 6 months and 15 years old were evaluated for DENV infection at days 0 and 15 by DENV PCR and IgM ELISA. In the second study (2009–2012), clusters of 200-meter radius were triggered by DENV-infected index cases admitted to the provincial hospital. Subjects of any age ≥6 months were evaluated for DENV infection at days 0 and 14. In both studies, subjects who were DENV PCR positive at day 14/15 were considered to have been “susceptible” on day 0. Comparison subjects from houses in which someone had documented DENV infection, but the subject remained DENV negative at days 0 and 14/15, were considered “non-susceptible.” Day 0 samples were presumed to be from just before virus exposure, and underwent plaque reduction neutralization testing (PRNT). Seventeen “susceptible” (six DENV-1, five DENV-2, and six DENV-4), and 32 “non-susceptible” (13 exposed to DENV-1, 10 DENV-2, and 9 DENV-4) subjects were evaluated. Comparing subjects exposed to the same serotype, receiver operating characteristic (ROC) curves identified homotypic PRNT titers of 11, 323 and 16 for DENV-1, -2 and -4, respectively, to differentiate “susceptible” from “non-susceptible” subjects.

Conclusions/Significance

PRNT titers were associated with protection from infection by DENV-1, -2 and -4. Protective NTs appeared to be serotype-dependent and may be higher for DENV-2 than other serotypes. These findings are relevant for both dengue epidemiology studies and vaccine development efforts.     

BeeDoctor,a Versatile MLPA-Based Diagnostic Tool for Screening Bee Viruses

The long-term decline of managed honeybee hives in the world has drawn significant attention to the scientific community and bee-keeping industry. A high pathogen load is believed to play a crucial role in this phenomenon, with the bee viruses being key players. Most of the currently characterized honeybee viruses (around twenty) are positive stranded RNA viruses. Techniques based on RNA signatures are widely used to determine the viral load in honeybee colonies. High throughput screening for viral loads necessitates the development of a multiplex polymerase chain reaction approach in which different viruses can be targeted simultaneously. A new multiparameter assay, called “BeeDoctor”, was developed based on multiplex-ligation probe dependent amplification (MLPA) technology. This assay detects 10 honeybee viruses in one reaction. “BeeDoctor” is also able to screen selectively for either the positive strand of the targeted RNA bee viruses or the negative strand, which is indicative for active viral replication. Due to its sensitivity and specificity, the MLPA assay is a useful tool for rapid diagnosis, pathogen characterization, and epidemiology of viruses in honeybee populations. “BeeDoctor” was used for screening 363 samples from apiaries located throughout Flanders; the northern half of Belgium. Using the “BeeDoctor”, virus infections were detected in almost eighty percent of the colonies, with deformed wing virus by far the most frequently detected virus and multiple virus infections were found in 26 percent of the colonies.     

Activation of a functional idiotype network response by monoclonal antibody specific for a virus (M-MuLV)-induced tumor antigen

BALB/c mice were injected with IgM mAb specific for Moloney murine leukemia virus (M-MuLV)-determined cell surface Ag in an attempt to inhibit Moloney sarcoma growth. The monoclonal IgM significantly inhibited sarcoma growth when given to the mice after inoculation with Moloney murine sarcoma/leukemia virus, and also potentiated the in vivo antibody response specific for M-MuLV Ag. These responses were significantly greater than the primary response to the virus alone in age- and sex-matched control mice, and were also seen in mice which were injected with the IgM antibody only and not with virus, suggesting that an Ag-independent mechanism may be involved. The M-MuLV-specific serum antibody responses induced by the monoclonal IgM, with or without prior virus inoculation, were predominantly of the IgG1 isotype, with some IgG2a; no other isotypes were found to have titers significantly higher than in the normal response to virus alone. M-MuLV-specific IgG1 was detected only in mice injected with monoclonal IgM, and not in the response to virus alone. The same sera also had high titers of anti-idiotypic antibodies, (Ab2), as well as anti-anti-idiotypic antibodies (Ab3). It appears, therefore, that passive immunization with M-MuLV-specific IgM mAb activates an idiotypic network, which results in both Ab2 and Ab3 responses; the M-MuLV-specific response may be considered a subset of Ab3.     

Value of anti-infective chemoprophylaxis in primary systemic vasculitis: what is the evidence?

Although infections are a major concern in patients with primary systemic vasculitis, actual knowledge about risk factors and evidence concerning the use of anti-infective prophylaxis from clinical trials are scarce. The use of high dose glucocorticoids and cyclophosphamide pose a definite risk for infections. Bacterial infections are among the most frequent causes of death, with Staphylococcus aureus being the most common isolate. Concerning viral infections, cytomegalovirus and varicella-zoster virus reactivation represent the most frequent complications. The only prophylactic measure that is widely accepted is trimethoprim/sulfamethoxazole to avoid Pneumocystis jiroveci pneumonia in small vessel vasculitis patients with generalised disease receiving therapy for induction of remission.     

Development of a challenge-protective vaccine concept by modification of the viral RNA-dependent RNA polymerase of canine distemper virus

We demonstrate that insertion of the open reading frame of enhanced green fluorescent protein (EGFP) into the coding sequence for the second hinge region of the viral L (large) protein (RNA-dependent RNA polymerase) attenuates a wild-type canine distemper virus. Moreover, we show that single intranasal immunization with this recombinant virus provides significant protection against challenge with the virulent parental virus. Protection against wild-type challenge was gained either after recovery of cellular immunity postimmunization or after development of neutralizing antibodies. Insertion of EGFP seems to result in overattenuation of the virus, while our previous experiments demonstrated that the insertion of an epitope tag into a similar position did not affect L protein function. Thus, a desirable level of attenuation could be reached by manipulating the length of the insert (in the second hinge region of the L protein), providing additional tools for optimization of controlled attenuation. This strategy for controlled attenuation may be useful for a “quick response” in vaccine development against well-known and “new” viral infections and could be combined efficiently with other strategies of vaccine development and delivery systems.