Janet Neequaye

Two approximately 300 kilodalton plasmodium falciparum proteins at the surface membrane of infected erythrocytes.

Two very large Plasmodium falciparum proteins are identified as constituents of the infected erythrocyte membrane. Sera were obtained from Aotus monkeys that had been repeatedly infected with asexual P. falciparum from one of four strains. The capacity of these sera to block in vitro cytoadherence of infected erythrocytes and agglutinate intact infected cells was determined. The sera were also used to immunoprecipitate protein antigens from detergent extracts of 125I-surface labeled or biosynthetically radiolabeled infected erythrocytes. For each serum/antigen combination, precipitation of only one protein correlated with the ability of the serum to interfere with cytoadherence and agglutinate infected cells. This malarial protein, denoted Pf EMP 1 (P. falciparum-erythrocyte-membrane-protein 1) bore strain-specific epitope(s) on the cell surface and displayed size heterogeneity (Mr approximately 220,000-350,000). Pf EMP 1 was strongly labeled by cell-surface radioiodination but was a quantitatively very minor malarial protein. Pf EMP 1 was distinguished by its size, surface accessibility and antigenic properties from a more predominant malarial protein in the same size range (Pf EMP 2) that is under the infected erythrocyte membrane at knobs. Monoclonal antibodies and rabbit antisera raised against Pf EMP 2 were used to show that this size heterogeneous antigen was indistinguishable from the previously described MESA (mature parasite infected erythrocyte surface antigen), identified by precipitation with rabbit antisera raised against the MESA hexapeptide repeats. Antibodies raised against Pf EMP 2/MESA did not precipitate Pf EMP 1. We conclude that Pf EMP 1 is either directly responsible for the cytoadherence phenomenon, or is very closely associated with another as yet unidentified functional molecule. Pf EMP 2/MESA must have a structural property/function that is important under the host cell membrane.

Factors that could influence the spread of AIDS in Ghana, West Africa: Knowledge of AIDS, sexual behavior, prostitution, and traditional medical practices

Summary:Ghana is a West African nation in the early stages of the human immunodeficiency virus (HIV) epidemic. In a series of surveys done between 1987 and 1989, we examined factors related to the spread of HIV infection, including knowledge about the acquired immune deficiency syndrome (AIDS), sexual habits, use of prostitutes, traditional healer practices, and skin-piercing customs. Although a polygamous society, three-fourths of married men had only one wife. The number of sexual partners at any one time was generally low. However, the divorce rate was more than 29% and 55% of married men had current sexual partners in addition to their wives. Knowledge about AIDS was widespread, yet 4% of men interviewed had had a sexual encounter with a prostitute within the last month. Use of condoms was very limited and 66% of customers of high-class prostitutes refused to use a condom even after a request to do so by the prostitute. Skin piercing, including scarification, was done by an unsterile instrument by 39% of 74 rural traditional healers, many of whom had more than one patient per day. To combat the spread of AIDS, Ghanaians will have to apply their knowledge of AIDS risk factors to their actual behavior. Many of the social customs are products of poverty and its ensuing social consequences. Funds are needed for specific AIDS prevention programs as well as improved education and health care throughout the country.

African Burkitt Lymphoma: Age-Specific Risk and Correlations with Malaria Biomarkers

African Burkitt lymphoma is an aggressive B-cell, non-Hodgkin lymphoma linked to Plasmodium falciparum malaria. Malaria biomarkers related to onset of African Burkitt lymphoma are unknown. We correlated age-specific patterns of 2,602 cases of African Burkitt lymphoma (60% male, mean ± SD age = 7.1 ± 2.9 years) from Uganda, Ghana, and Tanzania with malaria biomarkers published from these countries. Age-specific patterns of this disease and mean multiplicity of P. falciparum malaria parasites, defined as the average number of distinct genotypes per positive blood sample based on the merozoite surface protein-2 assessed by polymerase chain reaction, were correlated and both peaked between 5 and 9 years. This pattern, which was strong and consistent across regions, contrasted parasite prevalence, which peaked at 2 years and decreased slightly, and geometric mean parasite density, which peaked between 2 and 3 years and decreased sharply. Our findings suggest that concurrent infection with multiple malaria genotypes may be related to onset of African Burkitt lymphoma.

Endemic Burkitt lymphoma is associated with strength and diversity of Plasmodium falciparum malaria stage-specific antigen antibody response

Endemic Burkitt lymphoma (eBL) is linked to Plasmodium falciparum (Pf) infection geographically, but evidence from individual-level studies is limited. We investigated this issue among 354 childhood eBL cases and 384 age-, sex-, and location-matched controls enrolled in Ghana from 1965 to 1994. Immunoglobulin G1 (IgG1) and immunoglobulin G3 (IgG3) antibodies to antigens diagnostic of recent infection Pf histidine-rich protein-II (HRP-II) and 6NANP, Pf-vaccine candidates SE36 and 42-kDa region of the 3D7 Pf merozoite surface protein-1 (MSP-1), and tetanus toxoid were measured by indirect enzyme-linked immunoassay. Odds ratios (ORs) and 95% confidence intervals (CIs) for association with eBL were estimated using unconditional logistic regression. After adjustments, eBL was positively associated with HRP-IIIgG3 seropositivity (adjusted OR: 1.60; 95% CI 1.08-2.36) and inversely associated with SE36IgG1 seropositivity (adjusted OR: 0.37; 95% CI 0.21-0.64) and with tetanus toxoidIgG3 levels equal or higher than the mean (adjusted OR: 0.46; 95% CI 0.32-0.66). Anti-MSP-1IgG3 and anti-6NANPIgG3 were indeterminate. eBL risk was potentially 21 times higher (95% CI 5.8-74) in HRP-IIIgG3-seropositive and SE36IgG1-seronegative responders compared with HRP-IIIgG3-seronegative and SE36IgG1-seropositive responders. Our results suggest that recent malaria may be associated with risk of eBL but long-term infection may be protective.

Comparative trial of oral versus intramuscular chloroquine in children with cerebral malaria

One hundred and thirteen children aged 12 years or less with cerebral malaria in Accra, Ghana were treated with chloroquine either with a low dose regime of 3.5 mg/kg 8-hourly intramuscularly, or orally by nasogastric tube, in a standard regime, both to a total of 25 mg/kg body weight. There was no obvious difference in outcome in the 2 treatment groups. The overall mortality of 5.3% (5.9% and 4.4% in the oral and intramuscular treatment groups respectively) was similar to that seen 10 years ago in this hospital. The average parasite clearance time had increased to 61 h, compared to 41 h noted 10 years ago. The incidence of hypoglycaemia (3%) was very low compared to studies in other malaria endemic areas. The reason for this is not clear but it could have contributed to the low mortality. Neurological deficits were seen on day 14 in 7.8% of patients. Parasitaemia recurred within 14 d in 22% of surviving patients, confirming the presence of RI/RII chloroquine resistance in Accra.

Intrathecal chemoprophylaxis in the prevention of central nervous system relapse in Burkitt's lymphoma

A retrospective review of patients treated for endemic Burkitts lymphoma in Ghana was undertaken to evaluate the efficacy of intrathecal (IT) chemoprophylaxis in preventing central nervous system (CNS) relapse. Patients treated before 1974 received no IT chemoprophylaxis and those treated between 1974 and 1979 received IT methotrexate in addition to systemic chemotherapy. In patients presenting with facial disease only (Stages I–II), there was no significant difference in the frequency of CNS relapse between those receiving IT chemoprophylaxis and those not receiving any. CNS relapse was, however, significantly reduced in patients presenting with abdominal disease (Stage III) who received IT chemoprophylaxis in addition to systemic combination therapy. This was associated with an improved survival.

Changes in presenting tumour site of Burkitt's lymphoma in Ghana, West Africa, 1965-1978.

Between 1965 and 1978, 430 cases of Burkitts lymphoma were evaluated at the Burkitt Tumour Project, Accra, Ghana. During this period a change in the presenting features occurred, in which abdominal disease increased and facial disease decreased. This change was especially apparent in males, in whom the proportion of cases with abdominal disease more than doubled (chi 2 time trend = 25.99, P = 0.00000017) We speculate that the change may be related to possible changes in BL incidence.

Geographic/Ethnic Differences in Human Herpesvirus-6 Antibody Patterns

Serum samples from healthy adults in four geographic/ethnic groups (Ghanaian Blacks, Malaysian Chinese, Malaysian Indians and United States Caucasians) were tested under code for antibodies to human herpesvirus‐6 (HHV‐6). The prevalence and titer of HHV‐6 antibody in the healthy Ghanaians were significantly higher than in the Malaysian Chinese; United States Caucasians and Malaysian Indians had intermediate prevalence and titer of antibodies. Thus far, no specific differences in HHV‐6‐associated diseases have been noted between geographic/ethnic groups with these marked variations in antibody patterns.

Epstein-Barr virus from Burkitt Lymphoma biopsies from Africa and South America share novel LMP-1 promoter and gene variations

Epstein Barr virus (EBV) sequence variation is thought to contribute to Burkitt lymphoma (BL), but lack of data from primary BL tumors hampers efforts to test this hypothesis. We directly sequenced EBV from 12 BL biopsies from Ghana, Brazil, and Argentina, aligned the obtained reads to the wild-type (WT) EBV reference sequence, and compared them with 100 published EBV genomes from normal and diseased people from around the world. The 12 BL EBVs were Type 1. Eleven clustered close to each other and to EBV from Raji BL cell line, but away from 12 EBVs reported from other BL-derived cell lines and away from EBV from NPC and healthy people from Asia. We discovered 23 shared novel nucleotide-base changes in the latent membrane protein (LMP)-1 promoter and gene (associated with 9 novel amino acid changes in the LMP-1 protein) of the 11 BL EBVs. Alignment of this region for the 112 EBV genomes revealed four distinct patterns, tentatively termed patterns A to D. The distribution of BL EBVs was 48%, 8%, 24% and 20% for patterns A to D, respectively; the NPC EBV’s were Pattern B, and EBV-WT was pattern D. Further work is needed to investigate the association between EBV LMP-1 patterns with BL.

Antibodies reactive to Plasmodium falciparum serine repeat antigen in children with Burkitt lymphoma from Ghana

The role of protective immunity to Plasmodium falciparum (Pf) malaria in Burkitt lymphoma (BL) is unknown. We investigated the association between BL and antibodies reactive to SE36 antigen, a recombinant protein based on P. falciparum serine repeat antigen 5 gene, targeted by protective malaria immune responses. Cases were children (0–14 years) enrolled at the Korle‐Bu Teaching Hospital, Accra, Ghana, during 1965–1994 with BL confirmed by histology or cytology (92% of cases). Controls were apparently healthy children enrolled contemporaneous to the cases from the nearest neighbor house to the case house and were age,‐ sex‐frequency‐matched to the cases. Anti‐SE36 IgG antibodies were measured using enzyme‐linked absorbent immunoassays (ELISAs). SE36 titers were estimated by extrapolating ELISA optical density readings to a standard fitting curve. Anti‐SE36 titers were log‐transformed for analysis. Odds ratios (ORs) and two‐sided 95% confidence intervals (95% CIs) were estimated using unconditional logistic regression. The mean log endpoint dilution titers were 0.63 logs lower in cases than in controls (8.26 [SD 1.68] vs. 8.89 [SD 1.75], Students t‐test, p = 0.019). Lower titers were observed in cases than controls aged 0–4 years (p = 0.05) and in those aged 5–14 years (p = 0.06). Low and medium tertiles of anti‐SE36 IgG antibodies were associated with increased OR for BL ([OR 1.67, 95% CI 1.21–2.31] and [OR 1.33, 95% CI 0.96–1.86], respectively, ptrend = 0.002) in analyses adjusting for age, sex, calendar period and test plate. Our findings suggest that compared to similarly aged children enrolled from the same community, children with BL in Ghana have lower antibodies to SE36 antigen.