Charlotte A. Moser

Circulating Rotavirus-Specific Antibody-Secreting Cells (ASCs) Predict the Presence of Rotavirus-Specific ASCs in the Human Small Intestinal Lamina Propria

Rotaviruses are the most important cause of infectious diarrhea in children throughout the world. Protection is most likely mediated by small-intestinal virus-specific IgA. However, neither fecal nor serum virus-specific IgA clearly correlates with protection against challenge. The capacity of rotavirus-specific antibodies and rotavirus-specific antibody-secreting cells (ASCs) in the circulation to predict the presence of ASCs in the intestines of children was evaluated. Mononuclear cells from intestinal biopsy samples and blood from 21 children were enriched for CD38, a marker of terminally differentiated B cells, and evaluated for the presence of virus-specific and total IgA- and IgG-secreting cells, by ELISPOT assay. Serum virus-specific IgA and IgG levels were determined by ELISA. The ratio of virus-specific to total IgA-secreting cells in the blood correlated with that found in the small, but not large, intestine. In contrast, serum rotavirus-specific IgA correlated less well with the presence of virus-specific ASCs in the small intestine.

B2 but Not B1 Cells Can Contribute to CD4+ T-Cell-Mediated Clearance of Rotavirus in SCID Mice

ABSTRACT Studies utilizing various immunodeficient mouse models of rotavirus (RV) infection demonstrated significant roles of RV-specific secretory immunoglobulin A (IgA), CD4+ T cells, and CD8+T cells in the clearance of RV and protection from secondary infection. Secretion of small but detectable amounts of IgA in RV-infected αβ T-cell receptor knockout mice (11) and distinctive anatomical localization and physiology of B1 cells suggested that B1 cells might be capable of producing RV-specific intestinal IgA in a T-cell-independent fashion and, therefore, be responsible for ablation of RV shedding. We investigated the role of B1 cells in the resolution of primary RV infection using a SCID mouse model. We found that the adoptive transfer of unseparated peritoneal exudate cells ablates RV shedding and leads to the production of high levels of RV-specific intestinal IgA. In contrast, purified B1 cells do not ablate RV shedding and do not induce a T-cell-independent or T-cell-dependent, RV-specific IgA response but do secrete large amounts of polyclonal (total) intestinal IgA. Cotransfer of mixtures of purified B1 cells and B1-cell-depleted peritoneal exudate cells differing in IgA allotypic markers also demonstrated that B2 cells (B1-cell-depleted peritoneal exudate cells) and not B1 cells produced RV-specific IgA. To our knowledge, this is the first observation that B1 cells are unable to cooperate with CD4+ T cells and produce virus-specific intestinal IgA antibody. We also observed that transferred CD4+ T cells alone are capable of resolving RV shedding, although no IgA is secreted. These data suggest that RV-specific IgA may not be obligatory for RV clearance but may protect from reinfection and that effector CD4+ T cells alone can mediate the resolution of primary RV infection. Reconstitution of RV-infected SCID mice with B1 cells results in the outgrowth of contaminating, donor CD4+ T cells that are unable to clear RV, possibly because their oligoclonal specificities may be ineffective against RV antigens.

Hypertrophy, Hyperplasia, and Infectious Virus in Gut-Associated Lymphoid Tissue of Mice after Oral Inoculation with Simian-Human or Bovine-Human Reassortant Rotaviruses

Oral inoculation of infants with a vaccine that contains simian-human reassortant rotaviruses has been found to be a rare cause of intussusception. Because intussusception can be associated with enlargement of gut-associated lymphoid tissue, we studied the capacity of simian-human and bovine-human reassortant rotaviruses to cause lymphoid hypertrophy and hyperplasia of Peyers patches (PP) of adult BALB/c mice. Neither hypertrophy nor hyperplasia was detected in PP after oral inoculation with simian-human or bovine-human reassortant rotaviruses. However, infectious virus was detected in PP and mesenteric lymph nodes after oral inoculation with simian, but not bovine, reassortant rotaviruses. Implications of these findings on the pathogenesis of intussusception are discussed.

Aqueous-based microencapsulation enhances virus-specific humoral immune responses in mice after parenteral inoculation

Vaccines are commonly administered by the parenteral route. Therefore, adjuvant strategies which include parenteral immunization may improve the efficacy of a number of current vaccines. The capacity of aqueous-based microencapsulation to enhance virus-specific IgG responses in mice inoculated intramuscularly with small quantities of antigen was evaluated. Mice were inoculated with either 10(4), 10(3), or 10(2) p.f.u. of microencapsulated rotavirus (bovine strain WC3), placebo microcapsules plus free virus, or virus alone. Mice were subsequently bled 1, 2, 4, 6, and 9 months after inoculation. Microencapsulation of rotavirus enhanced virus-specific humoral immune responses. In addition, virus-containing microcapsules composed of spermine-chondroitin sulfate induced levels of virus-specific antibodies greater than those found after inoculation with virus-containing microcapsules composed of spermine-alginate. Mechanisms by which microencapsulation may enhance virus-specific humoral immunity are discussed.

Effect of microencapsulation on immunogenicity of a bovine herpes virus glycoprotein and inactivated influenza virus in mice

We previously found that aqueous-based spermine-alginate or spermine-chondroitin sulfate microcapsules enhanced rotavirus-specific humoral immune responses after intramuscular inoculation of mice. To extend our observations with whole, infectious rotavirus to vaccine strategies which include inactivated virus and purified proteins, we determined the capacity of aqueous-based microcapsules to enhance virus-specific immune responses to bovine herpes virus type 1 glycoprotein D (BHV-1-gD) or ether-treated influenza virus. We found that spermine-alginate microcapsules decreased the quantity of BHV-1-gD necessary to induce protein-specific antibodies about 5000-fold. However, spermine-alginate microcapsules did not enhance influenza virus-specific antibody responses. Microcapsules composed of spermine-chondroitin sulfate did not enhance either BHV-1-gD or influenza virus-specific immune responses. Possible mechanisms of enhancement of virus-specific antibody responses by microencapsulation are discussed.

Distribution of rotavirus-specific memory B cells in gut-associated lymphoid tissue after primary immunization.

We found previously that mice inoculated orally with simian rotavirus strain RRV developed virus-specific memory B cell responses 16 weeks after immunization that were greater than those found 6 weeks after immunization. Memory B cell responses were defined as the quantity of virus-specific IgA detected in small intestinal lamina propria (LP) fragment cultures of immunized mice at various intervals after challenge. Enhanced memory B cell responses correlated with enhanced protection against shedding. In order to understand better the delayed onset of rotavirus-specific memory B cell responses, a method was developed to determine the frequencies of rotavirus-specific memory B cells in gut-associated lymphoid tissues (GALT). We found that protection against rotavirus challenge was determined by the frequency of rotavirus-specific memory B cells in GALT LP.

Delivering Influenza Vaccine to High-Risk Adults Subspecialty Physician Practices

Influenza is responsible for significant morbidity and mortality in the United States. Despite long-standing national recommendations, only 47% of adults with a high-risk condition received the influenza vaccine in 2009-2010. Subspecialty practices provide a significant portion of ambulatory care visits for high-risk adults and understanding their role in the immunization infrastructure may increase immunization rates, decrease public health burden, and reduce influenza-associated disease. A cross-sectional survey of cardiology, pulmonology, and obstetrics/gynecology practices was conducted to assess influenza vaccination practices, plans, patient acceptance, frustrations, and reasons for not vaccinating. It was found that 51% of respondents planned to vaccinate patients. Plans differed significantly by practice type. Practices that do not vaccinate generally recommend vaccination and refer patients to public health clinics, primary care, and pharmacies.   Administrative and patient-related barriers affected most practices, but practices that vaccinate were able to overcome these barriers. Improvements in vaccination may be addressed by adapting practice support services for subspecialty practices.

Funding the Costs of Disease Outbreaks Caused by Non-vaccination

While vaccination rates in the United States are high - generally over 90 percent - rates of exemptions have been going up, and preventable diseases coming back. Aside from their human cost and the financial cost of treatment imposed on those who become ill, outbreaks impose financial costs on an already burdened public health system, diverting resources from other areas. This article examines the financial costs of non-vaccination, showing how high they can be and what they include. It makes a case for requiring those who do not vaccinate to cover the costs of outbreak caused by their choice. Such recouping is justified because the choice not to vaccinate can easily be seen as negligent. But even if it is not, that choice involves imposing costs on others, and there are good reasons to require the actors to internalize those costs. The article proposes alternative statutory and regulatory schemes to cover the costs imposed on the public purse, focusing on no-fault mechanisms. We consider both ex ante mechanisms like a tax or a fee that will go into a no-fault fund to cover the costs and ex post mechanisms like a statutory authorization for recoupment of those costs by health officials.

The impact of access to immunization information on vaccine acceptance in three countries

Introduction Vaccine acceptance is a critical component of sustainable immunization programs, yet rates of vaccine hesitancy are rising. Increased access to misinformation through media and anti-vaccine advocacy is an important contributor to hesitancy in the United States and other high-income nations with robust immunization programs. Little is known about the content and effect of information sources on attitudes toward vaccination in settings with rapidly changing or unstable immunization programs. Objective The objective of this study was to explore knowledge and attitudes regarding vaccines and vaccine-preventable diseases among caregivers and immunization providers in Botswana, the Dominican Republic, and Greece and examine how access to information impacts reported vaccine acceptance. Methods We conducted 37 focus groups and 14 semi-structured interviews with 96 providers and 153 caregivers in Botswana, the Dominican Republic, and Greece. Focus groups were conducted in Setswana, English, Spanish, or Greek; digitally recorded; and transcribed. Transcripts were translated into English, coded in qualitative data analysis software (NVivo 10, QSR International, Melbourne, Australia), and analyzed for common themes. Results Dominant themes in all three countries included identification of health care providers or medical literature as the primary source of vaccine information, yet participants reported insufficient communication about vaccines was available. Comments about level of trust in the health care system and government contrasted between sites, with the highest level of trust reported in Botswana but lower levels of trust in Greece. Conclusions In Botswana, the Dominican Republic, and Greece, participants expressed reliance on health care providers for information and demonstrated a need for more communication about vaccines. Trust in the government and health care system influenced vaccine acceptance differently in each country, demonstrating the need for country-specific data that focus on vaccine acceptance to fully understand which drivers can be leveraged to improve implementation of immunization programs.

Factors Associated With Pediatrician Responses to Alternative Immunization Schedule Requests

We conducted a cross-sectional online survey among 4 chapters of the American Academy of Pediatrics from July through October 2014 to describe characteristics of pediatricians and practices associated with practice-level responses to alternative immunization schedule requests. Among 374 pediatricians, 58% reported frequent alternative immunization schedule requests and 24% reported feeling comfortable using them. Pediatricians who work in practices that accommodate alternative immunization schedule requests have increased odds of having a high frequency of alternative immunization schedule requests, and beliefs that relationships with families would be negatively affected if they refused requests. Practices that discontinue care to families who request alternative immunization schedules have increased odds of being a private group practice and having a formal office vaccine policy. Pediatricians are frequently asked to use alternative immunization schedules and many are not comfortable using them. Practice-level responses to alternative immunization schedules are associated with characteristics of pediatricians and practices.