The effect of HIV-exposure on immune responses to expanded programme on immunization vaccines and antigens

Includes abstract.Includes bibliographical references.Immunization against vaccine-preventable infections is essential to reducing childhood morbidity and mortality. The immaturity and tolerogenicity of the immune system of infants renders them susceptible to infectious diseases and makes induction of protective immunity via vaccines a challenge. HIV-exposed infants are HIV uninfected and born to HIV-infected mothers and have increased morbidity and mortality of unknown aetiology. We hypothesise that T cells of HIV-exposed uninfected (HEU) infants have impaired proliferative ability and cytokine production in response to vaccine antigens than HIV unexposed (HU) infants

The impact of myeloid derived suppressor cells on vaccine immunogenicity in South African HIV-infected and uninfected mothers and their infants

BACKGROUND: Each year over 4 million infants die from infections, of which many are vaccinepreventable. Young infants respond poorly to vaccines, but the basis of reduced immunity is controversial. We hypothesized that myeloid-derived suppressor cells (MDSC) that might be induced during gestation, would persist at birth leading to active suppression of infant-immune responses. OBJECTIVE: We evaluated the ontogeny of MDSC and the effect of MDSC on vaccine immunogenicity during early life in South African infants and mothers, and in HIVexposed uninfected (HEU) infants and HIV+ mothers. METHODS: HIV-infected and uninfected mothers and their infants were recruited from Khayelitsha, Cape Town and followed-up for one year. In whole PBMC and after MDSC (CD15+) depleted, we measured BCG, Hepatitis B, Tetanus toxoid and Bordetella pertussis vaccine-specific CD4+ T cell proliferation by CFSE and IFN-γ responses using ELISpot assay

Myeloid derived suppressor cells are present at high frequency in neonates and suppress in vitro T cell responses

Over 4 million infants die each year from infections, many of which are vaccine-preventable. Young infants respond relatively poorly to many infections and vaccines, but the basis of reduced immunity in infants is ill defined. We sought to investigate whether myeloid-derived suppressor cells (MDSC) represent one potential impediment to protective immunity in early life, which may help inform strategies for effective vaccination prior to pathogen exposure. We enrolled healthy neonates and children in the first 2 years of life along with healthy adult controls to examine the frequency and function of MDSC, a cell population able to potently suppress T cell responses. We found that MDSC, which are rarely seen in healthy adults, are present in high numbers in neonates and their frequency rapidly decreases during the first months of life. We determined that these neonatal MDSC are of granulocytic origin (G-MDSC), and suppress both CD4+ and CD8+ T cell proliferative responses in a contact-dependent manner and gamma interferon production. Understanding the role G-MDSC play in infant immunity could improve vaccine responsiveness in newborns and reduce mortality due to early-life infections

FAM111B dysregulation promotes malignancy in fibrosarcoma and POIKTMP and a low-cost method for its mutation screening

Introduction: Mutations in the uncharacterised human FAM111B gene are associated with POIKTMP, a rare multi-organ fibrosing disease. Recent studies also reported the overexpression of FAM111B in specific cancers. Moreover, FAM111B mutation screening may prove expensive in under-resourced facilities. Therefore, this study investigated its cellular function and dysfunction and described an inexpensive mutation screening method. Materials and Methods: FAM111B expression was assessed in silico and validated in vitro in cell lines and primary skin fibroblasts from a South African POIKTMP-patient with the heterozygous FAM111B gene mutation: NM_198947.4: c.1861T>G (p. Tyr621Asp or Y621D) by qPCR and western blot. The cellular function of FAM111B was studied in HT1080 using various cell-based functional assays, and the Y621D mutation was genotyped by PCR-RFLP. Results: Expression studies showed upregulated FAM111B mRNA and protein in the cancer cells. High FAM111B expression with robust nuclear localization occurred in HT1080. Additionally, expression data and cell-based assays indicated that FAM111B led to the upregulation of cell migration, decreased cell apoptosis, and modulatory effects on cell proliferation. Y621D mutation showed similar effects on cell migration but minimal impact on cell apoptosis. FAM111B mRNA and protein expression were markedly downregulated (p ≤ 0.05) in the POIKTMP-patient's fibroblasts. The PCR-RFLP method successfully genotyped Y621D gene mutation. Discussion: FAM111B is a cancer-associated nuclear protein: Its modulation by mutations or overexpression may contribute to the malignancy of cancers and POIKTMP/fibrosis and poor clinical outcomes and represents a viable prognostic marker or therapeutic target. Furthermore, the PCR-RFLP method could prove a valuable tool for FAM111B mutation validation or screening in resource-constrained laboratories

Influenza Vaccination Uptake and Hesitancy among Healthcare Workers in Early 2021 at the Start of the COVID-19 Vaccine Rollout in Cape Town, South Africa

Vaccination attitudes among healthcare workers (HCWs) predict their level of vaccination uptake and intention to recommend vaccinations to their patients. To our knowledge, no study has been conducted in South Africa to assess hesitancy toward influenza vaccines among HCWs. We adapted a questionnaire developed and validated by Betsch and colleagues and used it to conduct online and face-to-face interviews among HCWs at the start of the COVID-19 vaccine rollout. Multivariate logistic regression was used to assess predictors of influenza vaccine hesitancy. Of 401 participants, 64.5% were women, 49.2% were nurses, and 12.5% were physicians. A total of 54.9% were willing to accept, 20.4% were undecided, and 24.7% intended to refuse influenza vaccination. Participants who were above 25 years of age and physicians were more likely to accept the vaccine. Key predictors of vaccine acceptance were confidence in the effectiveness, consideration of benefits and risks, and willingness to be vaccinated to protect others. Influenza vaccine hesitancy was highest in those who did not trust that influenza vaccines are safe. For future flu seasons, tailored education programs on the safety and effectiveness of flu vaccines targeting younger HCWs, could be vital to improving vaccine uptake

Effect of neonatal G-MDSC on T cell proliferation.

<p>(<b>A</b>) Proliferative responses of purified T cells in the presence or absence of G-MDSC after anti-CD3/CD28 bead stimulation (n = 28 independent experiments performed in duplicate for CD3 plots, n = 6 for CD4 and CD8 plots). Significance determined by the Wilcoxon Matched-Pair Signed Rank test. (<b>B</b>) Proliferative responses of purified adult naïve T cells (n = 9 independent experiments performed in duplicate) compared to cord blood T cells (n = 28 independent experiments performed in duplicate) after anti-CD3/CD28 bead stimulation. Statistical significance determined by the Mann Whitney test. (<b>C</b>) Suppression of T cell proliferation by autologous G-MDSC titration. (n = 4 independent experiments performed in duplicate). (<b>D</b>) Suppression of T cell proliferative responses by G-MDSC is contact dependent. (n = 5 independent experiments performed in duplicate). (<b>E</b>) G-MDSC frequency correlates with suppression of T cell proliferation by G-MDSC. G-MDSC frequencies were correlated to suppression of T cell proliferation by G-MDSC using the Spearman rank correlation test (n = 16 independent experiments).</p

Characterization and longitudinal analysis of MDSC populations in cord blood, infants and adults.

<p>(<b>A</b>) Gating strategy and identification of HLA-DR/CD14^neg, CD33/CD11b/CD15^pos G-MDSC in adult and cord blood. Further characterization of HLA-DR/CD14^neg, CD33/CD11b/CD15^pos cells by intracellular staining of Arginase I. (<b>B</b>) Frequency of HLA-DR/CD14^neg, CD33/CD11b/CD15^pos cells of: (i) CBMC isolated from CB collected from healthy pregnancies in Seattle, WA (n = 25); (ii) PBMC isolated from neonates in Cape Town, South Africa at 6-weeks of age (n = 9); (iii) PBMC isolated from 6–24 month-old infants in Seattle, WA (n = 29); (iv) and PBMC isolated from healthy adults in Seattle, WA (n = 28). Statistical significance determined by the Mann Whitney test. (<b>C</b>) Wright-Giemsa cytospin of CB samples and phenotype determination by clinical pathology of neutrophils and G-MDSC (Average, n = 2 independent experiments). Magnification 600X. (<b>D</b>) Proportions of neutrophils at various stages of development in the neutrophil and the G-MDSC fractions.</p

Delaying BCG vaccination until 8 weeks of age results in robust BCG-specific T-cell responses in HIV-exposed infants

Background: BCG vaccination prevents disseminated tuberculosis in children, but it is contraindicated for persons with human immunodeficiency virus (HIV) infection because it can result in severe disease in this population. In tuberculosis-endemic regions, BCG vaccine is administered soon after birth, before in utero and peripartum HIV infection is excluded. We therefore assessed the immunogenicity of BCG vaccine in HIV-exposed infants who received BCG at birth or at 8 weeks of age. Methods: HIV-exposed, uninfected infants were randomly assigned to receive BCG vaccination at birth (the early vaccination arm) or 8 weeks of age (the delayed vaccination arm). BCG-specific proliferative and intracellular cytokine responses were assessed in 28 infants per arm at 6, 8, and 14 weeks of life. Results: There was no difference in BCG-specific T-cell proliferation between the study arms 6 weeks after vaccination. However, at 14 weeks of age, the frequency of interferon γ-expressing CD4+ T cells and multifunctional BCG-specific responses in the delayed vaccinated arm were significantly higher than those in the early vaccination arm (P =. 021 and P =. 011, respectively). Conclusions.The immunogenicity of BCG vaccination in HIV-exposed, uninfected infants is not compromised when delayed until 8 weeks of age and results in robust BCG-specific T-cell responses at 14 weeks of age. These findings support further evaluation of this modified BCG vaccination strategy for HIV-exposed infants. Clinical Trials Registration.NCT02062580

Effect of G-MDSC on IFN-gamma production.

<p>(<b>A</b>) Cord blood CD3^pos T cells and adult CD3^pos CD45RO^neg T cells were assessed for IFN-gamma production by ELISpot after anti-CD3/CD28 bead stimulation (n = 11 independent experiments performed in triplicate for neonates and 9 independent experiments for adults). Statistical significance determined by the Mann Whitney test. (<b>B</b>) Neonatal G-MDSC decrease IFN-gamma production after anti-CD3/CD28 bead stimulation. (n = 13 independent experiments performed in triplicate). (<b>C</b>) G-MDSC frequency correlation with suppression T cell of IFN-gamma production by G-MDSC. G-MDSC frequencies were correlated to suppression using the Spearman rank correlation test (n = 11 independent experiments).</p