Publications by authors named "John Ngowi"

Background: Kaposi sarcoma (KS) is a neoplastic disease etiologically associated with infection by the Kaposi sarcoma-associated herpesvirus (KSHV). KS manifests primarily as cutaneous lesions in individuals due to either age (classical KS), HIV infection (epidemic KS), or tissue rejection preventatives in transplantation (iatrogenic KS) but can also occur in individuals, predominantly in sub-Saharan Africa (SSA), lacking any obvious immune suppression (endemic KS). The high endemicity of KSHV and human immunodeficiency virus-1 (HIV) co-infection in Africa results in KS being one of the top 5 cancers there.

View Article and Find Full Text PDF

Objectives: To longitudinally compare SARS-CoV-2-specific T cell and humoral immune responses between convalescent individuals who are HIV-positive (HIV+) and HIV-negative (HIV-).

Methods: We conducted enzyme-linked immunospots to determine the SARS-CoV-2-specific T cell responses to spike and nucleocapsid, membrane protein, and other open reading frame proteins (NMO), whereas an immunofluorescence assay was used to determine the humoral responses. Participants were sampled at baseline and after 8 weeks of follow-up.

View Article and Find Full Text PDF

Background: Despite the high COVID-19 morbidity and mortality rates across the world, the reported rates in sub-Saharan Africa (SSA), which has a higher burden of other infectious diseases and overwhelmed healthcare systems, remain relatively low. This study aims to better understand the potential factors that contribute to this phenomenon, especially among cancer patients who are considered as a high-risk group for developing severe COVID-19.

Methods: Plasma samples collected during the COVID-19 pandemic from SARS-CoV-2 unvaccinated cancer and potential blood donor populations were analyzed for SARS-CoV-2 (spike and nucleocapsid proteins) antibodies by an immunofluorescence assay.

View Article and Find Full Text PDF
Article Synopsis
  • * Plasma samples were collected from 20 individuals exposed to or recovering from COVID-19, revealing that all subjects had SARS-CoV-2 specific IgG antibodies, with most showing high levels of nAb and strong ADCC activity.
  • * The results suggest that vaccines should not only assess neutralizing antibodies but also the ability to mediate ADCC, highlighting the need for a broader understanding of immune responses to SARS-CoV-2.
View Article and Find Full Text PDF

Objective: Significant morbidity and mortality have occurred in the USA, Europe, and Asia due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), whereas the numbers of infections and deaths in sub-Saharan Africa (SSA) have remained comparatively low. It has been hypothesized that exposure of the population in SSA to other coronaviruses prior to the COVID-19 pandemic resulted in some degree of cross-protection against SARS-CoV-2 infection and pathogenesis. We evaluated this hypothesis by comparing SARS-CoV-2 cross-reactive antibodies in pre-pandemic plasma samples collected from SSA and the USA.

View Article and Find Full Text PDF

Purpose: Albinism affects some facets of the eye's function and coloration, as well as hair and skin color. The prevalence of albinism is estimated to be one in 2,000-5,000 people in sub-Saharan Africa and one in 270 in Tanzania. People in Tanzania with albinism experience sociocultural and economic disparities.

View Article and Find Full Text PDF

In sub-Saharan Africa, endemic Kaposi's sarcoma (EnKS) is still prevalent despite high incidence of epidemic Kaposi's sarcoma (EpKS) resulting from the on-going HIV-1 epidemic. While KSHV is clearly the etiologic agent of KS, the mechanisms underlying KS development are not fully understood. For example, HIV-1 co-infection and concomitant immune dysfunction have been associated with EpKS development.

View Article and Find Full Text PDF

Kaposi's sarcoma-associated herpes virus (KSHV) is the etiologic agent for Kaposi's sarcoma (KS). The prognostic utility of KSHV and HIV-1 (human immunodeficiency virus) viremia as well as immunological parameters in clinical management of participants with KS is unclear. The objective of this study was to investigate viral and immunological parameters as predictors of KS treatment responses in participants with KS from sub-Saharan Africa (SSA).

View Article and Find Full Text PDF

Despite the close association between Kaposi's sarcoma (KS) and immune dysfunction, it remains unclear whether tumor infiltrating immune cells (TIIC), by their absence, presence, or dysfunction, are mechanistically correlated with KS pathogenesis. Therefore, their potential capacity to serve as prognostic biomarkers of KS disease progression or control is unclear. Because epidemic-KS (EpKS) occurs with HIV-1 co-infection, it is particularly important to compare TIIC between EpKS and HIV-negative African endemic-KS (EnKS) to dissect the roles of HIV-1 and Kaposi Sarcoma-associated herpesvirus (KSHV) in KS pathogenesis.

View Article and Find Full Text PDF

Objective: Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent for Kaposi's sarcoma (KS), one of the most common cancers in Tanzania. We have investigated KSHV prevalence and factors associated with KSHV infection in Tanzania.

Methods: This is a cross-sectional study of voluntary blood-donors from Dar es Salaam, Tanzania.

View Article and Find Full Text PDF

Background: Kaposi sarcoma (KS)-associated herpesvirus (KSHV) is etiologically linked to all KS forms, but mechanisms underlying KS development are unclear. The incidence of KS in human immunodeficiency virus type 1-infected (HIV-1+) individuals implicates immune dysregulation; however, the lack of characterization of KSHV immune responses in endemic KS makes the role of HIV-1 unclear. The study objective was to investigate the HIV-1 and KSHV roles in viral nucleic acid detection, antibody responses, and cytokine responses in polymerase chain reaction-confirmed epidemic KS and endemic KS patients and non-cancer controls from sub-Saharan Africa.

View Article and Find Full Text PDF

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS). It is endemic in a number of sub-Saharan African countries with infection rate of >50%. The high prevalence of HIV-1 coupled with late presentation of advanced cancer staging make KS the leading cancer in the region with poor prognosis and high mortality.

View Article and Find Full Text PDF