Contributions of biotechnology to the control and prevention of brucellosis in Africa

Zoonotic diseases such as brucellosis have a major impact on the health and economic prosperity of the developing world. Recent advances in our understanding of brucellosis and new developments in diagnostics and vaccine technology provide unique opportunities for biotechnology companies in developing countries to make an essential contribution to the control of this disease. Key Words: Brucellosis, biotechnology, zoonosis, livestock, public health, diagnostics, vaccine. African Journal of Biotechnology Vol.3(12) 2004: 631-63

Typing African Relapsing Fever Spirochetes

Sequencing distinguished relapsing fever from other borrelial species but not B. duttonii from B. recurrentis

Population Structure of East African Relapsing Fever Borrelia spp.

B. recurrentis may have evolved directly from B. duttonii

Portuguese hosts for Ornithodoros erraticus ticks

The hematophagous soft tick Ornithodoros erraticus feeds nocturnally on multiple warm-blooded vertebrate hosts. This tick is often found living buried in the soil of traditional pigpens. O. erraticus is an important infectious disease vector both for humans and animals. In the Iberian Peninsula, this tick serves as the vector of human tick-borne relapsing fever caused by the spirochete Borrelia hispanica. The natural ecosystems maintaining this spirochete are not well understood, with details of competent vertebrate reservoirs and tick–host interactions poorly understood. Investigation of arthropod blood meal composition provides evidence linking the vector to specific hosts, providing insights into possible disease reservoirs. Ticks collected from two pigpens located in southern Portugal were subjected to blood meal analysis. PCR amplification of vertebrate cytochrome b was used to disclose the original host from which 349 ticks had derived their previous blood meal. Host origins for blood meal analysis from 79 of 349 ticks revealed that 46.8% had previously fed from pigs, 35.4% human, 13.9% bovine, 5.1% sheep, 1.3% rodent, and 1.3% from birds. Three samples revealed mixed blood meals, namely, human–pig (1.3%), sheep–pig (1.3%), and bovine–pig (1.3%). The major role of pigs as hosts is consistent with fieldwork observations and underlines the importance of pigs for maintaining O. erraticus tick populations. Humans serve as accidental hosts, frequently confirmed by reports from both producers and veterinarians. Other livestock species and wildlife prevalent in the region appear only to have a minor role in maintaining this tick. The results demonstrate the importance of blood meal analysis to determine tick hosts providing a tool for investigation of sylvatic cycle for Borrelia hispanica

Shotgun genome sequence and population diversity of Mannheimia haemolytica isolates from sheep in South Africa

Respiratory disease caused by Mannheimia haemolytica is a major economic and welfare concern in the cattle and small stock industry worldwide. Disease occurs due to the interaction of numerous factors, including weaning stress, shipment, inclement weather, and overcrowding coupled with viral and bacterial infections. The whole genome of M. haemolytica strain Mh10517 was analyzed using an Illumina MiSeq high throughput sequencing platform. The genome size is 2.67 Mb with 2,879 predicted gene sequences. The molecular evolution and relatedness of M. haemolytica was investigated using nucleotide sequence data of seven housekeeping gene fragments from 21 ovine isolates. MEGA version 7.0 genomic workbench was used for alignment and analysis of the nucleotide data sets. For each gene fragment, the sequences were compared and isolates with identical sequences were assigned the same allele number. Results suggested that the 21 isolates belonged to six sequence types (ST) and ST 28 accounted for 33% of the isolates. Neighbour joining method was used to produce dendograms based on the concatenated sequences of the seven loci in multilocus allelic profile. There was significant variation between the number of synonymous and non-synonymous substitutions between each sequence pairs (p=0.018) based on results from the Fisher’s exact test of neutrality of sequence pairs. These preliminary data show substantial sequence variations and this supports the hypothesis that ovine isolates of M. haemolytica are more diverse that what has been reported for isolates from other species. These results will advance studies on various aspects of the biology of M. haemolytica in Africa, and the world at large.Poster presented at the University of Pretoria, Faculty of Veterinary Science Faculty Day, September 07, 2017, Pretoria, South Africa.Includes bibliographical referencesab201

High prevalence of <i>Rickettsia africae</i> variants in <i>Amblyomma variegatum</i> ticks from domestic mammals in rural western Kenya: implications for human health

Tick-borne spotted fever group (SFG) rickettsioses are emerging human diseases caused by obligate intracellular Gram-negative bacteria of the genus Rickettsia. Despite being important causes of systemic febrile illnesses in travelers returning from sub-Saharan Africa, little is known about the reservoir hosts of these pathogens. We conducted surveys for rickettsiae in domestic animals and ticks in a rural setting in western Kenya. Of the 100 serum specimens tested from each species of domestic ruminant 43% of goats, 23% of sheep, and 1% of cattle had immunoglobulin G (IgG) antibodies to the SFG rickettsiae. None of these sera were positive for IgG against typhus group rickettsiae. We detected Rickettsia africae–genotype DNA in 92.6% of adult Amblyomma variegatum ticks collected from domestic ruminants, but found no evidence of the pathogen in blood specimens from cattle, goats, or sheep. Sequencing of a subset of 21 rickettsia-positive ticks revealed R. africae variants in 95.2% (20/21) of ticks tested. Our findings show a high prevalence of R. africae variants in A. variegatum ticks in western Kenya, which may represent a low disease risk for humans. This may provide a possible explanation for the lack of African tick-bite fever cases among febrile patients in Kenya

Overlap subtype of chronic graft-versus-host disease is associated with an adverse prognosis, functional impairment, and inferior patient-reported outcomes: A Chronic Graft-versus-Host Disease Consortium study

Background The National Institutes of Health Consensus Conference proposed the term “overlap” graft-versus-host disease to describe the situation when both acute and chronic graft-versus-host disease are present. Design and Methods We examined whether the overlap subtype of graft-versus-host disease was associated with a different prognosis, functional limitations, or patient-reported outcomes compared to “classic” chronic graft-versus-host disease without any acute features. Results Prospective data were collected from 427 patients from nine centers. Patients were classified as having overlap (n=352) or classic chronic (n=75) graft-versus-host disease based on reported organ involvement. Overlap cases had a significantly shorter median time from transplantation to cohort enrollment (P=0.01), were more likely to be incident cases (P\u3c0.001), and had a lower platelet count at onset of the graft-versus-host disease (P\u3c0.001). Patients with overlap graft-versus-host disease had significantly greater functional impairment measured by a 2-minute walk test, higher symptom burden and lower Human Activity Profile scores. Quality of life was similar, except patients with overlap graft-versus-host disease had worse social functioning, assessed by the Short Form-36. Multivariable analysis utilizing time-varying covariates demonstrated that the overlap subtype of graft-versus-host disease was associated with worse overall survival (HR 2.1, 95% CI 1.1–4.7; P=0.03) and higher non-relapse mortality (HR 2.8, 95% CI 1.2–8.3; P=0.02) than classic chronic graft-versus-host disease. Conclusions These findings suggest that the presence of acute features in patients with chronic graft-versus-host disease is a marker of adverse prognosis, greater functional impairment, and higher symptom burden

Borrelia recurrentis employs a novel multifunctional surface protein with anti-complement, anti-opsonic and invasive potential to escape innate immunity

Borrelia recurrentis, the etiologic agent of louse-borne relapsing fever in humans, has evolved strategies, including antigenic variation, to evade immune defence, thereby causing severe diseases with high mortality rates. Here we identify for the first time a multifunctional surface lipoprotein of B. recurrentis, termed HcpA, and demonstrate that it binds human complement regulators, Factor H, CFHR-1, and simultaneously, the host protease plasminogen. Cell surface bound factor H was found to retain its activity and to confer resistance to complement attack. Moreover, ectopic expression of HcpA in a B. burgdorferi B313 strain, deficient in Factor H binding proteins, protected the transformed spirochetes from complement-mediated killing. Furthermore, HcpA-bound plasminogen/plasmin endows B. recurrentis with the potential to resist opsonization and to degrade extracellular matrix components. Together, the present study underscores the high virulence potential of B. recurrentis. The elucidation of the molecular basis underlying the versatile strategies of B. recurrentis to escape innate immunity and to persist in human tissues, including the brain, may help to understand the pathological processes underlying louse-borne relapsing fever

Characterisation of silent and active genes for a variable large protein of Borrelia recurrentis

BACKGROUND: We report the characterisation of the variable large protein (vlp) gene expressed by clinical isolate A1 of Borrelia recurrentis; the agent of the life-threatening disease louse-borne relapsing fever. METHODS: The major vlp protein of this isolate was characterised and a DNA probe created. Use of this together with standard molecular methods was used to determine the location of the vlp1(B. recurrentis A1) gene in both this and other isolates. RESULTS: This isolate was found to carry silent and expressed copies of the vlp1(B. recurrentis A1) gene on plasmids of 54 kbp and 24 kbp respectively, whereas a different isolate, A17, had only the silent vlp1(B. recurrentis A17) on a 54 kbp plasmid. Silent and expressed vlp1 have identical mature protein coding regions but have different 5' regions, both containing different potential lipoprotein leader sequences. Only one form of vlp1 is transcribed in the A1 isolate of B. recurrentis, yet both 5' upstream sequences of this vlp1 gene possess features of bacterial promoters. CONCLUSION: Taken together these results suggest that antigenic variation in B. recurrentis may result from recombination of variable large and small protein genes at the junction between lipoprotein leader sequence and mature protein coding region. However, this hypothetical model needs to be validated by further identification of expressed and silent variant protein genes in other B. recurrentis isolates

Possibilities for Relapsing Fever Reemergence

Increasing globalization may pave the way for reemergence of relapsing fever