39 research outputs found
South African buffalo-derived Theileria parva is distinct from other buffalo and cattle-derived T. parva
Theileria parva is a protozoan parasite transmitted by the brown-eared ticks,
Rhipicephalus appendiculatus and Rhipicephalus zambeziensis. Buffaloes are the
parasiteâs ancestral host, with cattle being the most recent host. The parasite has two
transmission modes namely, cattleâcattle and buffaloâcattle transmission. Cattleâcattle
T. parva transmission causes East Coast fever (ECF) and January disease syndromes.
Buffalo to cattle transmission causes Corridor disease. Knowledge on the genetic
diversity of South African T. parva populations will assist in determining its origin,
evolution and identify any cattleâcattle transmitted strains. To achieve this, genomic
DNA of blood and in vitro culture material infected with South African isolates (8160,
8301, 8200, 9620, 9656, 9679, Johnston, KNP2, HL3, KNP102, 9574, and 9581) were
extracted and paired-end whole genome sequencing using Illumina HiSeq 2500 was
performed. East and southern African sample data (Chitongo Z2, Katete B2, Kiambu
Z464/C12, Mandali Z22H10, Entebbe, Nyakizu, Katumba, Buffalo LAWR, and Buffalo
Z5E5) was also added for comparative purposes. Data was analyzed using BWA
and SAMtools variant calling with the T. parva Muguga genome sequence used as a
reference. Buffalo-derived strains had higher genetic diversity, with twice the number
of variants compared to cattle-derived strains, confirming that buffaloes are ancestral
reservoir hosts of T. parva. Host specific SNPs, however, could not be identified among
the selected 74 gene sequences. Phylogenetically, strains tended to cluster by host
with South African buffalo-derived strains clustering with buffalo-derived strains. Among
the buffalo-derived strains, South African strains were genetically divergent from other buffalo-derived strains indicating possible geographic sub-structuring. Geographic substructuring
was also observed within South Africa strains. The knowledge generated
from this study indicates that to date, ECF is not circulating in buffalo from South Africa. It
also shows that T. parva has historically been present in buffalo from South Africa before
the introduction of ECF and was not introduced into buffalo during the ECF epidemic.The Department of Agriculture, Land Reform and Rural Developmenthttp://www.frontiersin.org/Geneticsam2022Veterinary Tropical Disease
Pregnancy Incidence and Correlates during the HVTN 503 Phambili HIV Vaccine Trial Conducted among South African Women
HIV prevention trials are increasingly being conducted in sub-Saharan Africa. Women at risk for HIV are also at risk of pregnancy. To maximize safety, women agree to avoid pregnancy during trials, yet pregnancies occur. Using data from the HVTN 503/"Phambili" vaccine trial, we report pregnancy incidence during and after the vaccination period and identify factors, measured at screening, associated with incident pregnancy.To enrol in the trial, women agreed and were supported to avoid pregnancy until 1 month after their third and final vaccination ("vaccination period"), corresponding to the first 7 months of follow-up. Unsterilized women, pooled across study arms, were analyzed. Poisson regression compared pregnancy rates during and after the vaccination period. Cox proportional hazards regression identified associations with first pregnancy.Among 352 women (median age 23 yrs; median follow-up 1.5 yrs), pregnancy incidence was 9.6/100 women-years overall and 6.8/100 w-yrs and 11.3/100 w-yrs during and after the vaccination period, respectively [Rate Ratio = 0.60 (0.32-1.14), p = 0.10]. In multivariable analysis, pregnancy was reduced among women who: enrolled at sites providing contraception on-site [HR = 0.43, 95% CI (0.22-0.86)]; entered the trial as injectable contraceptive users [HR = 0.37 (0.21-0.67)] or as consistent condom users (trend) [HR = 0.54 (0.28-1.04)]. Compared with women with a single partner of HIV-unknown status, pregnancy rates were increased among women with: a single partner whose status was HIV-negative [HR = 2.34(1.16-4.73)] and; 2 partners both of HIV-unknown status [HR = 4.42(1.59-12.29)]. Women with 2 more of these risk factors: marijuana use, heavy drinking, or use of either during sex, had increased pregnancy incidence [HR = 2.66 (1.24-5.72)].It is possible to screen South African women for pregnancy risk at trial entry. Providing injectable contraception for free on-site and supporting consistent condom use may reduce incident pregnancy. Screening should determine the substance use, partnering, and HIV status of both members of the couple for both pregnancy and HIV prevention.SA National Health Research Database DOH-27-0207-1539; Clinicaltrials.gov NCT00413725
Neuropsychiatric Genetics of African Populations-Psychosis (NeuroGAPPsychosis): a case-control study protocol and GWAS in Ethiopia, Kenya, South Africa and Uganda
Neuropsychiatric Genetics of African Populations-Psychosis (NeuroGAPPsychosis): a case-control study protocol and GWAS in Ethiopia, Kenya, South Africa and Uganda
Genetic and antigenic variation of the bovine tick-borne pathogen Theileria parva in the Great Lakes region of Central Africa
BACKGROUND : Theileria parva causes East Coast fever (ECF), one of the most economically important tick-borne diseases
of cattle in sub-Saharan Africa. A live immunisation approach using the infection and treatment method (ITM)
provides a strong long-term strain-restricted immunity. However, it typically induces a tick-transmissible carrier state
in cattle and may lead to spread of antigenically distinct parasites. Thus, understanding the genetic composition of T.
parva is needed prior to the use of the ITM vaccine in new areas. This study examined the sequence diversity and the
evolutionary and biogeographical dynamics of T. parva within the African Great Lakes region to better understand the
epidemiology of ECF and to assure vaccine safety. Genetic analyses were performed using sequences of two antigencoding
genes, Tp1 and Tp2, generated among 119 T. parva samples collected from cattle in four agro-ecological zones
of DRC and Burundi.
RESULTS : The results provided evidence of nucleotide and amino acid polymorphisms in both antigens, resulting
in 11 and 10 distinct nucleotide alleles, that predicted 6 and 9 protein variants in Tp1 and Tp2, respectively. Theileria
parva samples showed high variation within populations and a moderate biogeographical sub-structuring due to the
widespread major genotypes. The diversity was greater in samples from lowlands and midlands areas compared to
those from highlands and other African countries. The evolutionary dynamics modelling revealed a signal of selective
evolution which was not preferentially detected within the epitope-coding regions, suggesting that the observed
polymorphism could be more related to gene flow rather than recent host immune-based selection. Most alleles
isolated in the Great Lakes region were closely related to the components of the trivalent Muguga vaccine.
CONCLUSIONS : Our findings suggest that the extensive sequence diversity of T. parva and its biogeographical distribution
mainly depend on host migration and agro-ecological conditions driving tick population dynamics. Such
patterns are likely to contribute to the epidemic and unstable endemic situations of ECF in the region. However, the fact that ubiquitous alleles are genetically similar to the components of the Muguga vaccine together with the limited
geographical clustering may justify testing the existing trivalent vaccine for cross-immunity in the region.Additional file 1: Table S1. Cattle blood sample distribution across agroecological
zones.Additional file 2: Table S2. Nucleotide and amino acid sequences of Tp1
and Tp2 antigen epitopes from T. parva Muguga reference sequence.Additional file 3: Table S3. Characteristics of 119 T. parva samples
obtained from cattle in different agro-ecological zones (AEZs) of The
Democratic Republic of Congo and Burundi.Additional file 4: Figure S1. Multiple sequence alignment of the 11 Tp1
gene alleles obtained in this study.Additional file 5: Table S4. Estimates of evolutionary divergence
between gene alleles for Tp1 and Tp2, using proportion nucleotide
distance.Additional file 6: Table S5. Tp1 and Tp2 genes alleles with their corresponding
antigen variants.Additional file 7: Table S6. Amino acid variants of Tp1 and Tp2 CD8+
T
cell target epitopes of T. parva from DRC and Burundi.Additional file 8: Figure S2. Multiple sequence alignment of the 10 Tp2
gene alleles obtained in this study.Additional file 9: Table S7. Distribution of Tp1 gene alleles of T. parva
from cattle and buffalo in the sub-Saharan region of Africa.Additional file 10: Table S8. Distribution of Tp2 gene alleles of T. parva
from cattle and buffalo in the sub-Saharan region of Africa.Additional file 11: Figure S3. Neighbor-joining tree showing phylogenetic
relationships among 48 Tp1 gene alleles described in Africa.Additional file 12: Figure S4. Phylogenetic tree showing the relationships
among concatenated Tp1 and Tp2 nucleotide sequences of 93 T.
parva samples from cattle in DRC and Burundi.This study is part of the PhD work supported by the University of Namur (UNamur,
Belgium) through the UNamur-CERUNA institutional PhD grant awarded
to GSA for bioinformatic analyses, interpretation of data and manuscript write
up in Belgium. The laboratory aspects (molecular biology analysis) of the
project were supported by the BecA-ILRI Hub through the Africa Biosciences
Challenge Fund (ABCF) programme. The ABCF Programme is funded by
the Australian Department for Foreign Affairs and Trade (DFAT) through the
BecA-CSIRO partnership; the Syngenta Foundation for Sustainable Agriculture
(SFSA); the Bill & Melinda Gates Foundation (BMGF); the UK Department for International Development (DFID); and the Swedish International Development
Cooperation Agency (Sida). The ABCF Fellowship awarded to GAS was
funded by BMGF grant (OPP1075938). Sample collection, field equipment and
preliminary sample processing were supported through the âTheileriaâ project
co-funded to the Université Evangélique en Afrique (UEA) by the Agence
Universitaire de la Francophonie (AUF) and the Communauté Economique
des Pays des Grands Lacs (CEPGL). The International Foundation for Science
(IFS, Stockholm, Sweden) supported the individual scholarship awarded to
GSA (grant no. IFS-92890CA3) for field work and part of field equipment to the
âTheileriaâ project.http://www.parasitesandvectors.comam2020Veterinary Tropical Disease
Women with pregnancies had lower adherence to 1% Tenofovir vaginal gel as HIV preexposure prophylaxis in CAPRISA 004, a phase IIB randomized-controlled trial.
Background: Antiretroviral prophylaxis may be a critical strategy to reduce periconception HIV transmission. Maximizing the benefit of periconception pharmacologic HIV risk-reduction requires an understanding of the links between pregnancy and adherence to this prevention strategy. Methods: We assessed study gel adherence among women with pregnancies compared to women without pregnancies enrolled in the CAPRISA 004 phase IIB trial of 1% vaginal tenofovir gel. Pregnancy was assessed with monthly urine tests. Adherence was measured monthly and defined as proportion of sex acts covered by two returned, used applicators based
on pre- and post-coital dosing. High adherence was defined as a median adherence score of >80%, that is, more than 80% of sex acts were covered by two applications of study gel. A multivariate generalized estimating equations (GEE) model with a binomial distribution was used to assess covariates associated with high adherence (>80%) over time. Median adherence before and after pregnancy was compared using Wilcoxon signed rank test. Results: Among 868 women, 53 had at least 1 pregnancy (4.06 per 100 woman years, 95% CI: 3.04, 5.31). Women with
pregnancies had lower median adherence compared to women without pregnancies (50% [IQR: 45â83] vs. 60% [IQR: 50â100], p = 0.02). Women with pregnancies also had a 48% lower odds of high adherence compared to women without pregnancies when adjusting for confounders (aOR 0.52, 95%CI: 0.41â0.66, p<0.0001). Among women with pregnancies,
adherence before and after pregnancy was not different (50% [IQR: 46â83] vs. 55% [IQR: 20â100], p = 0.68).
Conclusions: Women with pregnancies were less likely to have high adherence to study gel compared to women without pregnancies. Understanding these differences may inform findings from HIV prevention trials and future implementation of antiretroviral prophylaxis for at-risk women who choose to conceive. The protocol for the parent trial is registered on ClinicalTrials.gov, NCT00441298, http://www.clinicaltrials.gov/ct2/show/NCT00441298
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Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd
The epidemiology of tick-borne haemoparasites as determined by the reverse line blot hybridization assay in an intensively studied cohort of calves in western Kenya
AbstractThe development of sensitive surveillance technologies using PCR-based detection of microbial DNA, such as the reverse line blot assay, can facilitate the gathering of epidemiological information on tick-borne diseases, which continue to hamper the productivity of livestock in many parts of Africa and elsewhere. We have employed a reverse line blot assay to detect the prevalence of tick-borne parasites in an intensively studied cohort of indigenous calves in western Kenya. The calves were recruited close to birth and monitored for the presence of infectious disease for up to 51 weeks. The final visit samples from 453 calves which survived for the study period were analyzed by RLB. The results indicated high prevalences of Theileria mutans (71.6%), T. velifera (62.8%), Anaplasma sp. Omatjenne (42.7%), A. bovis (39.9%), Theileria sp. (sable) (32.7%), T. parva (12.9%) and T. taurotragi (8.5%), with minor occurrences of eight other haemoparasites. The unexpectedly low prevalence of the pathogenic species Ehrlichia ruminantium was confirmed by a species-specific PCR targeting the pCS20 gene region. Coinfection analyses of the seven most prevalent haemoparasites indicated that they were present as coinfections in over 90% of the cases. The analyses revealed significant associations between several of the Theileria parasites, in particular T. velifera with Theileria sp. sable and T. mutans, and T. parva with T. taurotragi. There was very little coinfection of the two most common Anaplasma species, although they were commonly detected as coinfections with the Theileria parasites. The comparison of reverse line blot and serological results for four haemoparasites (T. parva, T. mutans, A. marginale and B. bigemina) indicated that, except for the mostly benign T. mutans, indigenous cattle seem capable of clearing infections of the three other, pathogenic parasites to below detectable levels. Although the study site was located across four agroecological zones, there was little restriction of the parasites to particular zones