Molecular Assessment of Domain I of Apical Membrane Antigen I Gene in Plasmodium falciparum: Implications in Plasmodium Invasion, Taxonomy, Vaccine Development, and Drug Discovery.

Given its global morbidity and mortality rates, malaria continues to be a major public health concern. Despite significant progress in the fight against malaria, efforts to control and eradicate the disease globally are in jeopardy due to lack of a universal vaccine. The conserved short peptide sequences found in Domain I of Plasmodium falciparum apical membrane antigen 1 (PfAMA1), which are exposed on the parasite cell surface and in charge of Plasmodium falciparum invasion of host cells, make PfAMA1 a promising vaccine candidate antigen. The precise amino acids that make up these conserved short peptides are still unknown, and it is still difficult to pinpoint the molecular processes by which PfAMA1 interacts with the human host cell during invasion. The creation of a universal malaria vaccine based on the AMA1 antigen is challenging due to these knowledge limitations. This study used genome mining techniques to look for these particular short peptides in PfAMA1. Thirty individuals with Plasmodium falciparum malaria had blood samples taken using Whatman's filter papers. DNA from the parasite was taken out using the Chelex technique. Domain I of the Plasmodium falciparum AMA1 gene was amplified using nested polymerase chain reactions, and the amplified products were removed, purified, and sequenced. The DNA sequence generated was converted into the matching amino acid sequence using bioinformatic techniques. These amino acid sequences were utilized to search for antigenic epitopes, therapeutic targets, and conserved short peptides in Domain I of PfAMA1. The results of this investigation shed important light on the molecular mechanisms behind Plasmodium invasion of host cells, a potential PfAMA1 vaccine antigen sequence, and prospective malaria treatment options in the future. Our work offers fresh information on malaria medication and vaccine research that has not been previously discussed.

High genetic complexity but low relatedness in Plasmodium falciparum infections from Western Savannah Highlands and coastal equatorial Lowlands of Cameroon.

To determine the diversity and connectivity of infections in Northwestern and Southwestern Cameroon, 232 Plasmodium falciparum infections, collected in 2018 from the Ndop Health District (NHD) in the western savannah highlands in the Northwest and the Limbe Health District (LHD) in the coastal lowland forests in the Southwest of Cameroon were genotyped for nine neutral microsatellite markers. Overall infection complexity and genetic diversity was significantly (p < 0.05) lower in NHD than LHD, (Mean MOI = 2.45 vs. 2.97; Fws = 0.42 vs. 0.47; Mean He = 0.84 vs. 0.89, respectively). Multi-locus linkage disequilibrium was generally low but significantly higher in the NHD than LHD population (mean ISA= 0.376 vs 0.093). Consequently, highly related pairs of isolates were observed in NHD (mean IBS = 0.086) compared to those from the LHD (mean IBS = 0.059). Infections from the two regions were mostly unrelated (mean IBS = 0.059), though the overall genetic differentiation across the geographical range was low. Indices of differentiation between the populations were however significant (overall pairwise Fst = 0.048, Jost's D = 0.133, p < 0.01). Despite the high human migration across the 270km separating the study sites, these results suggest significant restrictions to gene flow against contiguous geospatial transmission of malaria in west Cameroon. Clonal infections in the highland sites could be driven by lower levels of malaria prevalence and seasonal transmission. How these differences in genetic diversity and complexity affect responses to interventions such as drugs will require further investigations from broader community sampling.

Epidemiological factors associated with HBV infection and uptake of testing in south west region of Cameroon: What can be done to scale up HBV testing in our setting?

Hepatitis B infection affects millions of people globally, partly due to its high degree of transmissibility and asymptomatic nature. This study was aimed at identifying prevailing epidemiological factors associated with HBV infection and testing uptake in the South West region of Cameroon. This hospital-based case-control study enrolled HBV infected participants and "healthy" controls ≥18 years old. Venous blood collected from participants was used to conduct HBV panel test (HBsAg, anti-HBs, HBeAg, anti-HBe, anti-HBc). Data on demographic and behavioral risk factors as well as reasons for taking the HBV test for the first time were collected using a questionnaire. A total of 424 participants were enrolled (212 "healthy" controls and 212 HBV infected cases). Male sex (odds ratio [OR] = 2.08, p = 0.010), ≤ secondary education level (OR = 4.83, p<0.001), low-income level (OR = 3.79, p<0.001), rural settlement (OR = 2.17, p = 0.031), history of sexually transmitted infections (STI) (OR = 4.24, p<0.001) and ignorance of sexual partners HBsAg status (OR = 2.70, p = 0.003) all had an independent and significant association with HBV infection. Top 3 reasons for doing HBsAg test were free screening (40.3%), blood donation (15.0%) and administrative requirements (14.9%). HBV testing uptake and early detection can be improved if more sensitization and free/opportunistic screenings are implemented. A significant drop in the cost of HBV test could encourage more people to get tested.

New species of Culex (Culiciomyia) (Diptera: Culicidae) from Talangaye Forest in Cameroon and descriptions and identification keys for males of the Afrotropical species of the subgenus.

Species of Culex (Diptera: Culicidae) belonging to the subgenus Culiciomyia were collected in partially logged areas and in surrounding pristine forest (Talangaye Forest) in the Nguti Subdivision in the South-West Region of Cameroon. Mosquitoes were collected mainly by sweep netting through forest floor vegetation. Morphological species identification of African Culiciomyia relies almost exclusively on the structure of the male genitalia and the shapes of comb scales on the maxillary palpi of males. Other features of males and the habitus of females are largely indistinguishable between the species of this subgenus. In total, seven currently described species and three new species were collected in the forest. The males of the three new species are described and named as Culex apicopilosus Cornel Mayi, sp. n., Culex lanzaroi Cornel Mayi, sp. n. and Culex pseudosubaequalis Cornel Mayi, sp. n. More detailed descriptions of males of the other currently known species that were collected in the Talangaye Forest and pictorial keys to the males of all Afrotropical species of Culiciomyia, including the new species, are provided.

A modified two-color flow cytometry assay to quantify in-vitro reinvasion and determine invasion phenotypes at low Plasmodium falciparum parasitemia.

Invasion of human red blood cells (RBCs) by Plasmodium parasites is a crucial yet poorly characterised phenotype. Two-color flow cytometry (2cFCM) promises to be a very sensitive and high throughput method for phenotyping parasite invasion. However, current protocols require high (~1.0%) parasitemia for assay set-up and need to be adapted for low parasitemia samples, which are becoming increasingly common in low transmission settings. Background fluorescence from nuclei-containing uninfected RBCs and high autologous reinvasion rates (merozoite invasion of donor uninfected RBCs present at 50% assay volume) are some of the limitations to the method's sensitivity to enumerate low parasitemia (<0.5%) with nucleic acid-based stains. Here, we describe modifications for plating unlabeled donor to labeled target RBCs per assay well and for gating parasitemia, that produces accurate quantifications of low reinvasion parasitemia. Plasmodium falciparum 3D7, Dd2 and field isolates at various low and high parasitemia (0.05%-2.0%) were used to set-up SyBr Green 1-based 2cFCM invasion assays. Target RBCs were labeled with CTFR proliferation dye. We show that this dye combination allowed for efficient parasite invasion into target RBCs and that a 1:3 ratio of unlabeled to labeled RBCs per assay greatly skewed autologous reinvasion (p < 0.001). Accuracy of quantifying reinvasion was limited to an assay parasitemia of 0.02% with minimal background interference. Invasion inhibition by enzymatic treatments increased averagely by 10% (p<0.05) across the entire parasitemia range. The effect was greater for samples with <0.5% parasitemia. Overall, a more sensitive method for phenotyping invasion of low P. falciparum parasitemia is described.

Genetic diversity and antiretroviral resistance-associated mutation profile of treated and naive HIV-1 infected patients from the Northwest and Southwest regions of Cameroon.

BACKGROUND: Antiretroviral therapy (ART) has improved the survival of HIV infected persons. However, rapid scale-up of ART and the high HIV-1 genetic variability, has greatly influenced the emergence of drug-resistant strains. This constitutes a potential threat to achieving the UNAIDS' 90-90-90 goals by 2020. We investigated the prevalent HIV-1 genotypes, drug resistance-associated mutations and assessed some predictors of the occurrence of these mutations. METHODS: This was a hospital-based cross-sectional study conducted between October 2010 and June 2012. Participants were consecutively enrolled from selected HIV treatment centers of the Southwest and Northwest regions of Cameroon. Viral load was determined with the automated Abbott Real-time HIV-1 m2000rt System. HIV genotyping and antiretroviral resistance mutations analysis were performed using Bayer's HIV-1 TRUGENE™ Genotyping Kit and OpenGene DNA Sequencing system. The drug resistance mutation was interpreted with the Stanford HIV database. Epidemiological data were obtained using pre-tested semi-structured questionnaires. RESULTS: Of the 387 participants, 239 were successfully genotyped. The median age of these participants was 33 years (interquartile range, IQR: 28-40 years), and a majority (65.7%) were female. A total of 29.3% of the participants were receiving ART. The median duration of ART was 10.5 months (IQR: 4-17.25 months). The median CD4 count and log10 viral load of study participants were 353.5 cells/ml (IQR:145-471) and 4.89 copies/ml (IQR: 3.91-5.55) respectively. CRF02 (A/G) (69%) was the most prevalent subtype followed by G (8.2%) and F (6.7%). Overall, resistance mutations were present in 37.1% of ART-experienced and 10.7% of ART-naive patients. Nucleoside reverse transcriptase inhibitors (NRTI) mutations occurred in 30% of ART-experienced and 2.4% of ART-naïve patients, while non-nucleoside reverse transcriptase inhibitors (NNRTI) mutations occurred in 34.2% of ART-experienced and 10.1% of -naïve patients. M184V (8.4%, 20/239) and K103N (5.4%, 13/239) were the most prevalent mutations. Major protease inhibitor mutations occurred in 3 (1.3%) out of the 239 sequences. The duration of ART independently predicted the occurrence of resistance mutation among ART-experienced patients. CONCLUSION: The high resistance to NNRTIs, which are the main support to the backbone (NRTIs) first-line antiretroviral regimen in Cameroon, has prompted the need to rollout an integrase strand transfer inhibitor regimen (containing Dolutegravir) with a higher genetic barrier to resistance as the preferred first line regimen.

Impact of deforestation on the abundance, diversity, and richness of Culex mosquitoes in a southwest Cameroon tropical rainforest.

Deforestation is a major threat to biodiversity but little data exist on how deforestation in real-time affects the overall mosquito species community despite its known role in the transmission of diseases. We compared the abundance and diversity of Culex mosquitoes before and after deforestation along a gradient of three different anthropogenic disturbance levels in a tropical rainforest in southwestern Cameroon. The collections were conducted in unlogged forest (January, 2016), selectively logged forest (January, 2017), and within a young palm plantation (October, 2017) using net traps, sweep nets, resting traps, and dipping for immature stages in water bodies. Mosquitoes were morphologically identified to subspecies, groups, and species. A total of 2,556 mosquitoes was collected of which 1,663 (65.06%) belong to the genus Culex, (n=427 (25.68%) in the unlogged forest; n=900 (54.12%) in the selectively logged forest; and n=336 (20.2%) in the young palm plantation) with a significant difference among the habitats. Diversity and richness of mosquitoes varied significantly among habitats with the highest values found in the selectively logged forest (H=2.4; DS=0.87; S=33) and the lowest value in the unlogged forest (H=1.37; DS=0.68; S=13). The results of this study showed that deforestation affects the abundance and diversity of Culex mosquitoes and favors the invasion of anthropophilic mosquitoes. Higher mosquito abundance and diversity in the selectively logged forest than in the pristine forest is notable and some explanations for these differences are discussed.

HBV Transmission Risk Assessment in Healthcare Workers, Household and Sexual Contacts of HBV Infected Patients in the Southwest Region of Cameroon.

OBJECTIVES: Hepatitis B virus (HBV) is known to be highly transmissible via the body fluids of an infected person. We investigated the transmission risks, awareness, and prevalence among healthcare workers (HCWs), household contacts (HHCs), and sexual partners (SPs) of HBV infected individuals. METHODS: We conducted a cross-sectional study of HCWs, HBV infected individuals as well as their corresponding HHCs and SPs. Data related to some transmission risks and HBV awareness was obtained from each participant using a questionnaire. Blood samples were collected from each participant and tested for hepatitis B surface antigen (HBsAg), hepatitis B e-antigen, and anti-hepatitis B core (anti-HBc). HBV viral load measurement was done for the HBV infected participants. RESULTS: A total of 596 participants were enrolled (127 HCWs, 128 HHCs, 138 SPs, and 203 HBV infected participants). HHCs (odds ratio (OR): 3.85, confidence interval (CI): 1.89-7.81), and SPs (OR: 3.04, CI: 1.51-6.17) were more associated with HBsAg/anti-HBc positivity compared to HCWs. Age, years spent with HBV infected partner, unprotected sex, and marriage were not identified as risk factors for HBV sexual transmission but cohabiting with an HBV infected SP was significantly (p = 0.005) associated with transmission (OR: 3.56, CI: 1.46-8.72). Female HHCs (OR: 2.48, CI: 1.06-5.80) and SPs (OR: 2.64, CI: 0.95-7.30) were more associated with HBsAg/anti-HBc positivity. The mean viral load (log IU) of HBV infected individuals (3.9±2.0) with HBsAg positive SPs was significantly higher than that of HBV infected individuals (2.8±1.0) with HBsAg negative SPs (p < 0.001). CONCLUSIONS: HHCs and SPs of HBV infected patients are more associated with HBV infection compared to HCWs. Horizontal transmission can as well be implicated among SPs since unprotected sex was not identified as a risk factor for transmission, but cohabitation was. Prompt management and preventive measures could be implemented if HHCs and SPs of HBV infected patients are identified, sensitized, and screened.

Cervical cancer in the Bamenda Regional Hospital, North West Region of Cameroon: a retrospective study.

INTRODUCTION: Cervical cancer is ranked the 7th most common cancer in the world. Cancer of the cervix is the second most commonly diagnosed cancer after breast cancer and the third leading cause of cancer deaths among females in less developed countries. Incidence rates are highest in countries with low income. Nearly 90% of cervical cancer deaths occur in developing parts of the world. The study researchers therefore, carried out a retrospective study to determine the proportion of cervical cancer among other types of cancer in the cancer registry of the Bamenda Regional Hospital. METHODS: The objective of this study was to determine the proportion of cervical cancer among other types of cancers in the cancer registry of the Bamenda Regional Hospital, North West Region of Cameroon from past records. We reviewed all records from the registry of patients who attended the Bamenda Regional Hospital to screen and/or be operated upon for cervical cancer and other types of cancer. Socio-demographic and clinical characteristics of cases were captured using a data collection sheet: age, type of cancer, stage of cancer, type of surgery carried out and date of surgery. Data were entered and analysed in Statistical Package for Social Sciences (SPSS) version 25 software. RESULTS: 59 cancer cases were received in the center between 2012 and 2017. Of these, 31 (52%) had cervical cancer. Most patients who screened positive for cancer of the cervix were of the 50-54 age groups. Most of these patients (47.5%), were received at late stages (stages 3 and 4). CONCLUSION: Over half (52%) of the patients receiving cancer care in this center have cervical cancer and generally turn up late for management.

Molecular characterization of influenza A(H1N1)pdm09 in Cameroon during the 2014-2016 influenza seasons.

In 2009, Influenza A(H1N1)pdm09 caused the first influenza pandemic of the 21st century with high mortality rates of about 284 500 deaths. This virus, however, continues to circulate as a seasonal influenza virus and to cause illness and deaths worldwide. In this study, we describe the genetic diversity of A(H1N1)pdm09 viruses collected between 2014 and 2016 in Cameroon. Three gene segments (HA, NA and M) of Cameroon strains were studied. The phylogenetic tree of the coding nucleotide sequences was generated by MEGA version 6.0 using a Maximum Likelihood method. The NA and M protein coding sequences were analyzed for the reported genetic markers of resistance against neuraminidase inhibitors and adamantanes, while predicted vaccine efficacy was estimated using the Pepitope method. Overall 39 strains were obtained. Phylogenetic analysis of the HA gene of influenza A(H1N1)pdm09 showed that Cameroon strains belonged to two major clades. The 2014 Cameroon sequences belonged to clade 6C while all sequences collected between 2015 and 2016 belonged to clade 6B. Majority of the samples had some mutations in the NA gene notably: I117M, N248D, and N369K while the amantadine-resistant M mutant, S31N, was found to be absent only in the two sequences collected in 2014. Overall, A/California/07/2009 vaccine strain showed a predicted vaccine efficacy of 24.55% to 35.77% against Cameroon A(H1N1)pdm09 strains circulating between 2014 and 2016. Our findings confirms the fast evolution of A(H1N1)pdm09 since its first introduction and highlights on the importance of influenza vaccine in reducing the burden caused by influenza in the community.

Characterization and assessment of HBV chronically infected patients: Identification of those eligible for treatment in the South West region of Cameroon.

BACKGROUND: The management of patients with chronic hepatitis B infection is quite complex because it requires an in-depth knowledge of the natural history of the disease. This study was aimed at characterizing HBV infected patients in order to determine the phase of the infection and identify the proportion eligible for treatment using 3 different guidelines. METHODS: HBV chronically infected patients (negative for HIV and HCV) were enrolled and the following tests were done for them: ALT, AST, HBV viral load, HBV serologic panel and Full blood count. APRI score was calculated for all patients. These patients were classified into immunotolerant, immune clearance, immune control and immune escape phases of the infection. The WHO and the 2018 AASLD criteria was also used to identify those who need treatment. Patients were clinically examined for signs and symptoms. Questionnaire was administered to all participants to ascertain their treatment status. Statistical analysis was done using SPSS version 21. RESULTS: A total of 283 participants (101 females and 182 males) with a mean age of 31.3±8.5 were enrolled. Fifty-two (18.4%) were eligible for treatment (Immune clearance and immune escape phases) and they recorded a significantly higher mean APRI score (0.71±0.51) as compared to those in the immune control and immune tolerant phase (0.43±0.20). Based on WHO and AASLD criteria, 12(4.2%) and 15 (5.3%) were eligible for treatment respectively and these were all subsets of the 52 cases mentioned above. Six (2.1%) and 29 (10.2%) of those identified under the immune control phase were on tenofovir and traditional medication respectively. CONCLUSION: Considering treatment for patients in the immune clearance and immune escape phases of the infection can be a reliable strategy to implement in our setting as this may probably tie with considerations from other treatment guidelines. Fifty-two (18.4%) patients were eligible for treatment and none of them were among the 2.1% of patients put on Tenofovir based treatment. This calls for the need for more trained health experts to periodically assess patients, implement an adequate treatment guideline and place the right patients on treatment in Cameroon.

Genetic characterization of influenza B virus in Cameroon and high frequency of reassortant strains.

Influenza B is broadly divided into B/Victoria and B/Yamagata lineages based on its genetic and antigenic properties. We describe in this study the first report on genome characterization of type B influenza virus in the Cameroon National Influenza Center (NIC) between 2014 and 2017. Respiratory samples were collected as part of the influenza surveillance activity in the NIC. RNA products were tested for the presence of influenza using the CDC Influenza A/B typing panel. Thirty-five samples positive for influenza B were selected for sequencing three gene segments (HA, NA, and M) and phylogenetic trees were generated by MEGA version 6.0. Nucleotide phylogenetic analysis of the HA gene revealed the presence of three major clades among Cameroonian strains. All Victoria lineages grouped into B/Victoria clade 1A, while, Yamagata lineages grouped into Yamagata clade 2 (2014 strains) and Yamagata clade 3 (2015-2017). We observed a high frequency of reassortant viruses with Yamagata-like HA gene and Victoria-like NA gene (27.4%; 23/84). The results from this study confirm variations in the genome composition of type B influenza virus and emphasize on the relevance of molecular surveillance for spotting peculiar genetic variants of public health and clinical significance.

Vaccine uptake and immune responses to HBV infection amongst vaccinated and non-vaccinated healthcare workers, household and sexual contacts to chronically infected HBV individuals in the South West Region of Cameroon.

BACKGROUND: HBV infection affects about 257 million people globally and Sub-Saharan Africa has the highest burden. The disease still constitutes a major public health problem despite the advent of preventive measures like the HBV vaccine. This study was aimed at identifying factors that influence vaccine uptake and the efficacy of administered vaccines among people at high risk of HBV infection. METHODS: This was a cross-sectional study conducted between January 2016 and December 2017. A pretested semi-structured questionnaire was used to capture information on sociodemographic and vaccination status from healthcare workers, household and sexual contacts to HBV infected people. HBV serological panel as well as quantitative anti-HBs ELISA test was done for all participants. Additional information was obtained from the institutions that administered the vaccines. RESULTS: A total of 265 participants with a mean age of 32.1±8.7 were enrolled. Eighty (30.2%) of them had received at least 1 dose of the HBV vaccine while 185 (69.8%) were unvaccinated. Healthcare workers were the most vaccinated (37%). Ignorance, negligence, fear of injection and the cost of the vaccine all contributed to poor vaccine uptake in the study population. Natural immunity was seen in 9 (3.4%) of the participants. Only 64.9% of the vaccinated participants attained the desirable level of anti-HBs (≥10mIU/ml) 1-2 months after ≥ 3 doses of the vaccine. Age, gender, obesity, alcohol and smoking were not significantly associated with poor immune responses. No standardized protocol was followed by the institutions administering the vaccine. CONCLUSION: This study revealed very poor vaccine uptake and poor immune responses to the HBV vaccine in the study population and this should urge the health sector in Cameroon to intensify their sensitization on HBV vaccine, standardize the protocol for storing and administering the vaccine, subsidize the cost of the vaccine especially amongst healthcare workers and encourage anti-HBs post vaccination testing.

Prescribing patterns and associated factors of antibiotic prescription in primary health care facilities of Kumbo East and Kumbo West Health Districts, North West Cameroon.

BACKGROUND: Inappropriate use of antibiotics is a global public health challenge and has been associated with antibiotic resistance. WHO reports show that efforts to promote rational antibiotic use in developing countries are poor. With the growing number of infections with antibiotic resistant bacteria, rational drug use becomes imperative and studies that promote rational drug use are highly necessary. Considering this, we investigated prescribing patterns and predictors of antibiotic prescription in primary health care facilities in Kumbo East (KE) and Kumbo West (KW) health districts in North West Cameroon, to contribute data which could influence policy on antibiotic use. METHODS AND FINDINGS: A cross sectional retrospective study was conducted from April 2014 to April 2015 in 26 randomly selected primary care facilities. Questionnaires were administered to 59 antibiotic prescribers to determine factors that predict antibiotic prescribing. Data on antibiotic prescription were collected by review of consultation registers. Prescription rates and demographics, prescriber and institution factors were analyzed using ANOVA. The best predictor of prescription was determined using multiple linear regression analysis. RESULTS: A total of 30,096 prescriptions were reviewed. Overall antibiotic prescription rate was 36.71%, with a mean of 1.14 antibiotics prescribed per patient. Amoxicillin was the most prescribed (29.9%). The most prevalent indications for prescribing were respiratory tract infections (21.27%). All antibiotics prescribed were broad-spectrum. Antibiotics were prescribed for patients with malaria and also in situations where diagnosis was uncertain. Prescribing by generic name was 98.36% while 99.87% was from Essential Drug List. Use of laboratory results, patient turnout and Performance Based Financing (PBF) were significantly associated with antibiotic prescribing rates (p < 0.05). PBF moderated prescribing. CONCLUSION: There was misuse of antibiotics in primary care facilities in study area. We recommend all primary care health facilities in study area to be included in the PBF scheme and that prescribing should only be done by physicians as the have adequate training.

Genetic diversity, viraemic and aminotransferases levels in chronic infected hepatitis B patients from Cameroon.

BACKGROUND: HBV infection annually accounts for 1 million deaths worldwide as a result of cirrhosis, liver failure, and hepatocellular carcinoma. In addition to varying responses to antiviral therapy, HBV genotypes have also been shown to be associated with different pattern of disease progression. Despite a high HBV prevalence of >8%, very few studies have been carried out in Cameroon to determine the genotype distribution across the country. The aim of this study was to determine the prevalent genotypes, level of viraemia and correlate these parameters with liver enzymes known to be the most affordable and widely used biomarkers for monitoring disease progression in Cameroon. METHODS: This was a hospital-community based study in which 81 participants who had been previously diagnosed of HBV were recruited and screened for HIV, HCV (for exclusion) and HBsAg for confirmation. Fifty known negative cases for HIV, HBV and HCV were tested and recruited to be used as healthy controls. Viral load and genotyping was performed only for HBV-mono infected cases using the Abbott RealTime HBV automated m2000 system and INNO-LiPA HBV Genotyping assay respectively. Liver enzymes were measured by spectrophotometry on both hepatitis B positive and healthy control cases. RESULTS: The mean alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were significantly higher (p < 0.001) in HBV infected patients than "healthy controls". Of the 81 HBV infected cases viral load was detected in 76 (93.8%) with mean viral load of 120,807 IU/ml ± 440,159 SD. Mean viral load was significantly different in patients with abnormal AST and ALT when compared with patients who had normal ALT and AST. The identified genotypes in order of prevalence were A (47.4%), E (39.5%), C/E (3.9%) A/C (2.6%), A/E (2.6%), B (1.3%), A/B (1.3%) and B/C (1.3%). CONCLUSION: Genotype E was significantly associated with higher mean viral load and mean AST levels. However, aminotransferase levels may not be a good marker for HBV disease progression as some patients could have normal levels but still present with very high viral loads and therefore, remain active HBV infection with possible high transmission.

Differential T-cell responses of semi-immune and susceptible malaria subjects to in silico predicted and synthetic peptides of Plasmodium falciparum.

Malaria remains a public health hazard in tropical countries as a consequence of the rise and spread of drug and insecticide resistances; hence the need for a vaccine with widespread application. Protective immunity to malaria is known to be mediated by both antibody and cellular immune responses, though characterization of the latter has been less extensive. The aim of the present investigation was to identify novel T-cell epitopes that may contribute to naturally acquired immune responses against malaria. Using the Microsoft software, Epitome™ T-cell peptide epitopes on 19 Plasmodium falciparum proteins in the Plasmodium Database (www.plasmodb.org.PlasmoDB 9.0) were predicted in-silico. The peptides were synthesized and used to stimulate peripheral blood mononuclear cells (PBMCs) in 14 semi-immune and 21 malaria susceptible subjects for interferon-gamma (IFN-γ) production ex-vivo. The level of IFN-γ production, a marker of T-cell responses, was measured by ELISPOT assay in semi-immune subjects (SIS) and frequently sick subjects (FSS) from an endemic zone with perennial malaria transmission. Of the 19 proteins studied, 17 yielded 27 pools (189 peptides), which were reactive with the subjects' PBMCs when tested for IFN-γ production, taking a stimulation index (SI) of ≥2 as a cutoff point for a positive response. There were 10 reactive peptide pools (constituting eight protein loci) with an SI of 10 or greater. Of the 19 proteins studied, two were known vaccine candidates (MSP-8 and SSP2/TRAP), which reacted both with SIS and FSS. Similarly the hypothetical proteins (PFF1030w, PFE0795c, PFD0880w, PFC0065c and PF10_0052) also reacted strongly with both SIS and FSS making them attractive for further characterization as mediators of protective immunity and/or pathogenesis.

Isolation and expression of UB05, a Plasmodium falciparum antigen recognised by antibodies from semi-immune adults in a high transmission endemic area of the Cameroonian rainforest.

BACKGROUND: Antibodies in adults living in malaria endemic areas that target specific parasite antigens are implicated in protective immunity to infection and disease. This study aimed to identify, isolate and characterise targets of protective immunity in malaria. A Plasmodium falciparum antigen termed UB05 (Genbank Accession Number DQ235690: PlasmoDB PF10_ 0372) that had been isolated by immunoscreening with semi-immune sera was studied. METHODS: Polymerase chain reaction, sequencing and bioinformatics were used to analyse the UB05 gene. A specific mouse anti-UB05 antibody was used in parasite reinvasion growth/inhibition assays and in immunoflourescence to localise the antigen. In a cross-sectional study, enzyme linked immunosorbent assay was used to study immunoglobulin G (IgG) responses to the antigen. RESULTS: The gene revealed significant homologies with gene sequences from Plasmodia and other apicomplexan parasites and had two alleles in the wild P. falciparum isolates. The antigen is expressed by schizonts and segmented merozoites. Mouse antibodies against it marginally inhibit in vitro invasion of erythrocytes by P. falciparum. The IgG responses to UB05 were found to be significantly lower (p<0.05) in the sera of children (2-5 years) compared with adults (>18 years), with or without parasitaemia. However, parasitaemia correlated inversely (r=0.7- 0.75) with serum anti-UB05 IgG concentrations. Furthermore, anti-UB05 IgG concentrations were lower in the sera of febrile patients (body temperature >37.5 degrees C) than their non-febrile counterparts regardless of parasitaemia status. CONCLUSIONS: These results are compatible with a role for UB05 in the development of immunity and as a marker of protective immunity to malaria.