Change in Anti- gp120 Human Monoclonal Antibody Isotype Significantly Improves HIV-1 Neutralization

HIV vaccine efforts tend to focus on the induction of IgG neutralizing antibodies. In part, this may stem from the observations that most HIV infected individuals fail to produce significant mucosal IgA. However, this is unlike most other infections and in turn it can be argued that mucosal IgA with appropriate function and specificity may contribute significantly to the prevention of HIV transmission. To explore this, we previously isotype switched F425A1g8, an anti-HIV CD4i human monoclonal antibody that binds to epitopes exposed upon CD4 binding (CD4i) The VH and VL chains were amplified from the IgG hybridoma and inserted into IgA1 or IgA2 and IgKappa vectors respectively. Stable cells lines were produced and antibody was collected and purified. Initial results showed that the IgA1 variant neutralized a number of HIV-1 isolates better than its parental form IgG1. We believe the increased neutralization of HIV is mainly due to the structural differences between IgG1 and IgA1. We hypothesize that the extended hinge of IgA1 may increase segmental flexibility and change the interaction of antibody with CD4i epitopes of the HIV, resulting in greater avidity. To look at this further, we have generated monomeric and dimeric IgA1 and IgA2 variants of three different CD4i antibodies: F425A1g8, 17b and E51. All antibody variants will be tested for immumoreactivity, HIV neutralization, prevention of transmission and ADCVI activity. Consistent with our previous results, there are significant differences in functional activity of the other CD4i antibodies with IgA1 more effective than the IgA2 variants. Additional activities will contribute to the hypothesis that the extended hinge region of the IgA1 antibody increases the antibodies ability to access the CD4i epitopes upon HIV-1 binding to CD4. These studies should impact on the design of active and passive immunotherapy and the prevention of HIV transmission

Humanized Mice for the Generation of HIV-1 Human Monoclonal Antibodies

Background: Despite the length of time HIV has been wreaking havoc on its victims, improvements in the prevention and treatment of HIV are needed. Anti-retroviral therapy can be effective but is expensive and not entirely accessible for people infected in third world countries. Several promising broadly neutralizing antibodies have been isolated from infected individuals; we propose that generating antigen specific human monoclonal antibodies using humanized mice further represents a promising approach to engineer prophylactic antibodies to reduce spread and infection of HIV. Methods: Immunodeficient mice were engrafted with fetal liver and thymus (BLT) prior to infection with different HIV isolates. HIV infection of the mice was monitored by viral load and antibody response followed by ELISA using gp120, gp41 or gp120/CD4 complex as antigens. Approximately 8-12 weeks post infection, spleens were harvested and splenocytes fused with human fusion partner HMMA 2.5 to isolate antibody-expressing hybridomas. Lead clones were scaled and purified for testing in functional assays such as TZM-bl neutralization assays as well as ADCVI to determine neutralizing and cytotoxic ability of the antibodies. Antibody sequences were also determined for analysis. Results: A robust, specific antibody response, of both IgG and IgA isotypes, was generated in response to HIV infection. Over 60 hybridomas were created that were not only immunoreactive with env antigens, but also had neutralization activity. Moreover, variable family usage was not limited and somatic mutation was clearly evident. Conclusions: These findings suggest that humanized BLT mice are a novel source for well-characterized, stable human monoclonal antibodies to HIV

Discovery and Development of Human Monoclonal Antibodies to Block RhD Alloimmunization During Pregnancy

Exposure of an Rh negative mother to red blood cells (RBCs) of an Rh positive fetus results in alloimmunization and development of anti-RhD antibodies. The anti-RhD antibodies cause hemolytic disease of the new born babies during subsequent pregnancies. Current prophylactic treatment involves polyclonal anti-RhD IgG purified from plasma of humans and is administered in approximately 20% of pregnancies. While the current prophylaxis is effective, it involves the use of human plasma and non-RhD specific antibodies, thus posing a risk of transmitting infections and undesired antibody reactions. Moreover, there is a serious scarcity of plasma donors to meet the requirement of anti-RhD antibodies. In this study we propose to discover and develop anti-RhD monoclonal human antibodies to replace the current polyclonal prophylaxis. We are using humanized BLT mice (fetal CD34+ stem cells, liver and thymus) reconstituted with RhD negative donor material and were immunized by using adenovirus containing RhD transgene. Serum samples were collected after 4-6 weeks of immunization. Our results show that the RhD immunized mice had considerably higher titer of IgG and IgA antibodies in the serum compared to the control, suggesting an immune response developed upon immunization. Splenocytes from antibody producing mice will be fused with a human fusion partner for the isolation of hybridomas producing human monoclonal antibodies. The immunoreactivity and functional activity of these antibodies will be discussed

Overcoming the Constraints of Anti-HIV/CD89 Bispecific Antibodies That Limit Viral Inhibition

Innovative strategies are necessary to maximize the clinical application of HIV neutralizing antibodies. To this end, bispecific constructs of human antibody F240, reactive with well-conserved gp41 epitope and antibody 14A8, reactive with the IgA receptor (CD89) on effector cells, were constructed. A F240 × 14A8 bispecific single chain variable region (scFv) molecule was constructed by linking two scFvs using a conventional GGGGS linker. Despite immunoreactivity with HIV gp41 and neutrophils, this bispecific scFv failed to inhibit HIV infection. This is in sharp contrast to viral inhibition using a chemical conjugate of the Fab of these two antibodies. Therefore, we constructed two novel Fab-like bispecific antibody molecules centered on fusion of the IgG1 CH1 domain or CH1-hinge domain to the C-terminus of F240scFv and fusion of the kappa chain CL domain to the C-terminus of 14A8scFv. Both Bi-Fab antibodies showed significant ADCVI activity for multiple clade B and clade C isolates by arming the neutrophils to inhibit HIV infection. The approach presented in this study is unique for HIV immunotherapy in that the impetus of neutralization is to arm and mobilize PMN to destroy HIV and HIV infected cells

Emotional experience in parents of children with Zellweger spectrum disorders: A qualitative study

Zellweger spectrum disorders (ZSDs) are rare, debilitating genetic diseases of peroxisome biogenesis that require constant management and lifelong care. Nevertheless, the experience of family caregivers for children diagnosed with ZSD is not well understood. In this study, we sought to characterize the emotional experience of ZSD family caregivers. Three 90-min focus groups were conducted with thirty-seven parents (25 mothers and 12 fathers) of children with ZSD during a family advocacy conference. Focus groups were arranged by age of proband (Group 1: 0–4 years, Group 2: 5–10 years, Group 3: >11 years). Audio recordings of focus groups were transcribed and analyzed using software for coding purposes. Analyzed content was validated using peer debriefing, member checking, and method triangulation. Focus group results showed that nearly a third of ZSD caregivers described their overall emotional experience as a “rollercoaster.” Additionally, three interconnected themes were identified: 1) range of emotions, 2) stressors, and 3) coping. Feeling overwhelmed and devastated were the most frequently described emotional responses. Corresponding stressors to these emotions included the burden of caregiver tasks associated with ZSD, and negative interactions with healthcare professionals. The most common coping strategies were acceptance of limitations of the diseases, redefining “normal” in the parenting experience, and advocating on behalf of the child and the patient community. This study underscores the profound emotional impact on parents who are caregivers for children with ZSDs, highlighting the utility of patient community feedback and qualitative approaches to fully characterize the overall family experience. Simple, targeted approaches focusing on improved communication between healthcare professionals and families, as well as offering resources for emotional support may greatly improve the lives of families living with ZSD and other rare pediatric diseases. Keywords: Peroxisome biogenesis disorder, Rare disease, Caregiver experience, Emotions, Coping, Qualitative researc

Emotional Experience in Parents of Children With Zellweger Spectrum Disorders: A Qualitative Study

Zellweger spectrum disorders (ZSDs) are rare, debilitating genetic diseases of peroxisome biogenesis that require constant management and lifelong care. Nevertheless, the experience of family caregivers for children diagnosed with ZSD is not well understood. In this study, we sought to characterize the emotional experience of ZSD family caregivers. Three 90-min focus groups were conducted with thirty-seven parents (25 mothers and 12 fathers) of children with ZSD during a family advocacy conference. Focus groups were arranged by age of proband (Group 1: 0–4 years, Group 2: 5–10 years, Group 3: \u3e11 years). Audio recordings of focus groups were transcribed and analyzed using software for coding purposes. Analyzed content was validated using peer debriefing, member checking, and method triangulation. Focus group results showed that nearly a third of ZSD caregivers described their overall emotional experience as a “rollercoaster.” Additionally, three interconnected themes were identified: 1) range of emotions, 2) stressors, and 3) coping. Feeling overwhelmed and devastated were the most frequently described emotional responses. Corresponding stressors to these emotions included the burden of caregiver tasks associated with ZSD, and negative interactions with healthcare professionals. The most common coping strategies were acceptance of limitations of the diseases, redefining “normal” in the parenting experience, and advocating on behalf of the child and the patient community. This study underscores the profound emotional impact on parents who are caregivers for children with ZSDs, highlighting the utility of patient community feedback and qualitative approaches to fully characterize the overall family experience. Simple, targeted approaches focusing on improved communication between healthcare professionals and families, as well as offering resources for emotional support may greatly improve the lives of families living with ZSD and other rare pediatric diseases

Human Anti-HIV-1 gp120 Monoclonal Antibodies with Neutralizing Activity Cloned from Humanized Mice Infected with HIV-1.

Broadly neutralizing, anti-HIV-1 gp120 mAbs have been isolated from infected individuals, and there is considerable interest in developing these reagents for Ab-based immunoprophylaxis and treatment. As a means to identify potentially new anti-HIV Abs, we exploited humanized NOD-scid IL2rγnull mice systemically infected with HIV-1 to generate a wide variety of Ag-specific human mAbs. The Abs were encoded by a diverse range of variable gene families and Ig classes, including IgA, and several showed significant levels of somatic mutation. Moreover, the isolated Abs not only bound target Ags with similar affinity as broadly neutralizing Abs, they also demonstrated neutralizing ability against multiple HIV-1 clades. The use of humanized mice will allow us to use our knowledge of HIV-1 gp120 structure and function, and the immune response targeting this protein, to generate native human prophylactic Abs to reduce the infection and spread of HIV-1

Oral administration of an anti-CfaE secretory IgA antibody protects against Enterotoxigenic Escherichia coli diarrheal disease in a non-human primate model [preprint]

Enterotoxigenic Escherichia coli (ETEC) is a leading cause of diarrhea-associated illness in developing countries. There is currently no vaccine licensed to prevent ETEC and the development of an efficacious prophylaxis would provide an intervention with significant impact. Recent studies suggested that effective protection could be achieved by inducing immunity to block colonization of ETEC. Here, we evaluated the efficacy of secretory (s) IgA2 and dimeric (d) IgA2 of an anti-colonization factor antigen antibody, 68-61, in the Aotus nancymaae non-human primate (NHP) ETEC challenge model via oral and parental delivery. Thirty-nine animals were distributed across 3 groups of 13, and challenged with 5.0×1011 cfu of H10407 on Day 0. Group 1 received a dIgA2 68-61 subcutaneously on day 0. Group 2 received a SIgA2 68-61 orally on days −1, 0, and +1, and Group 3 received an irrelevant SIgA2 antibody orally on days −1, 0, and +1. All animals were observed for symptoms of diarrhea, and stools were collected for ETEC colony counts. SIgA2 treatment significantly lowered the attack rate, resulting in a protective efficacy of 71.4% (p=0.025) in Group 2 as compared to Group 3. Anti-CfaE dIgA2 treatment group reduced the diarrheal attack rate, although the reduction did not reach significance (57.1%; P=0.072) as compared to the irrelevant SIgA2 Group 3. Our results demonstrated the feasibility of oral administration of SIgA as a potential immunoprophylaxis against enteric infections. To our knowledge, this is the first study to demonstrate the efficacy of administrated SIgA in a non-human primate model