Cooperativity of catalytic and lectin-like domain of T. congolense trans-sialidase modulates its catalytic activity

Trans-sialidases (TS) represent a multi-gene family of unusual enzymes, which catalyse the transfer of terminal sialic acids from sialoglycoconjugates to terminal galactose or N-acetylgalactosamine residues of oligosaccharides without the requirement of CMP-Neu5Ac, the activated Sia used by typical sialyltransferases. Most work on trypanosomal TS has been done on enzymatic activities of TS from T. cruzi (causing Chagas disease in Latin America), subspecies of T. brucei, (causing human sleeping sickness in Africa) and T. congolense (causing African Animal Trypanosomosis in livestock). Previously, we demonstrated that T. congolense TS (TconTS) lectin domain (LD) binds to several carbohydrates, such as 1,4-β-mannotriose. To investigate the influence of TconTS-LD on enzyme activities, we firstly performed in silico analysis on structure models of TconTS enzymes. Findings strongly supports the potential of domain swaps between TconTS without structural disruptions of the enzymes overall topologies. Recombinant domain swapped TconTS1a/TS3 showed clear sialidase and sialic acid (Sia) transfer activities, when using fetuin and lactose as Sia donor and acceptor substrates, respectively. While Sia transfer activity remained unchanged from the level of TconTS1a, hydrolysis was drastically reduced. Presence of 1,4-β-mannotriose during TS reactions modulates enzyme activities favouring trans-sialylation over hydrolysis. In summary, this study provides strong evidence that TconTS-LDs play pivotal roles in modulating enzyme activity and biological functions of these and possibly other TS, revising our fundamental understanding of TS modulation and diversity.

Molecular Prevalence of Trypanosome Infections in Kachia Grazing Reserve of Kaduna State Nigeria

African Animal Trypanosomosis (AAT) is a major factor limiting livestock productivity in large areas of humid and subhumid Africa. Astudy was conducted to estimate the prevalence of Trypanosomiasisin sheep and goats from Laduga, Kachia grazing reserve area of Kaduna State. Blood samples (5 ml) were randomly collected by venepuncture of the jugular vein, from 21 goats and 21 sheep of both sexes. The 42 blood samples were first screened by wet mount and samples were later analyzed by nested polymerase chain reaction (PCR) using generic primers that amplified the internal transcribed spacer-1 (ITS-1) gene region of the 16S rRNAgene. Microscopic examination revealed only 2.4% prevalence for T. vivax and 0% for T. brucei, whereas the DNA-based technique revealed 19.0% and 2.4% prevalence for T. vivax and T. brucei infections respectively, with the overall prevalence being 21.4%. Samples from goats revealed 13.6% and 5.0% prevalence of T. vivax in male and female respectively, while 4.5% and 0% prevalence of T. brucei was observed in male and female respectively. Similarly, samples from sheep revealed 9.1% and 10.0% prevalence of T. vivax in males and females respectively. Generally, the findings showed that tryponosomosis is more associated with males than females, there was however no significant different (P > 0.05). Furthermore, 23.8% and 19.0% prevalence was revealed by PCR in goats and sheep respectively. This shows that trypanosomiasis still exist and may worsen if not addressed properly in Kachia grazing reserve area of Kaduna State, and the use of microscopic evaluation alone might greatly underscore the prevalence rate. Keywords: Trypanosomosis, molecular diagnosis, prevalence, sheep and goats, Nigeria

Prevalence of trypanosomosis and associated haematological changes among hunting dogs in Abeokuta, Nigeria

African animal trypanosomosis (AAT) is one of the major constraints to the development of effective livestock production systems. Dogs are human companion and are believed to be sentinels for infection with the human species. This study was to detect subclinical and clinical infection of trypanosomes among hunting dogs in Abeokuta and its environs using molecular technique. A total of 87 dogs comprising of 49 males and 38 females were ramdomly screened for trypanosomes by polymerase chain reaction technique. Among 87 dogs screened, 17.2% were positive for Trypanosoma congolense and Trypanosoma brucei. Prevalence of trypanosomosis in males was 14.3% while the females accounted for 21.1%.Hematological examination revealed a significant increase (p < 0.05) in mean white blood cells (20.9 ± 2.11) and monocyte counts (5.9 ± 0.62) of the infected dogs compared to uninfected dogs. Packed Cell Volume (36.0 ± 3.73) and haemoglobin concentration (13.9 ± 2.10) decreased insignificantly, while, red blood cells (7.1 ± 0.87), lymphocyte (60.9 ± 9.63), neutrophil (33.3 ± 9.16) and eosinophil (1.4 ± 0.42) counts increased insignificantly (p > 0.05) in infected dogs compared to uninfected dogs. In conclusion, trypanosomosis is prevalent in hunting dogs, in Abeokuta.

Introduction of African Animal Trypanosomosis (AAT)/Nagana

African animal trypanosomosis (AAT), a livestock disease, also known as Nagana, tsetse fly disease, or tsetse disease, is a widespread tsetse-borne disease complex caused by unicellular protozoan parasites belonging to the genus Trypanosoma. It is one of the major constraints to the expansion of livestock rearing and livestock-based industries in Africa. It also constrains mixed farming, human health, and livelihood in tropical Africa. The tsetse fly is the major vector of the disease. Acute disease is characterized by marked depression, intermittent fever, anorexia, anemia, blood-tinged diarrhea, and adenopathy, sometimes petechiae on mucosa, abortion, and death if not treated. Diagnosis is made by observing trypanosome parasites by direct microscopic examination of blood, lymph nodes, edema fluid, or tissues. Treatment is by chemotherapy and chemoprophylaxis. Control is achieved through vector control treatment using available molecules and use of a few available trypanotolerant breeds of animals.

Mathematical modelling and control of African animal trypanosomosis with interacting populations in West Africa—Could biting flies be important in main taining the disease endemicity?

African animal trypanosomosis (AAT) is transmitted cyclically by tsetse flies and mechanically by biting flies (tabanids and stomoxyines) in West Africa. AAT caused by Trypanosoma congolense, T. vivax and T. brucei brucei is a major threat to the cattle industry. A mathematical model involving three vertebrate hosts (cattle, small ruminants and wildlife) and three vector flies (Tsetse flies, tabanids and stomoxyines) was described to identify elimination strategies. The basic reproduction number (R0) was obtained with respect to the growth rate of infected wildlife (reservoir hosts) present around the susceptible population using a next generation matrix technique. With the aid of suitable Lyapunov functions, stability analyses of disease-free and endemic equilibria were established. Simulation of the predictive model was presented by solving the system of ordinary differential equations to explore the behaviour of the model. An operational area in southwest Nigeria was simulated using generated pertinent data. The R0 < 1 in the formulated model indicates the elimination of AAT. The comprehensive use of insecticide treated targets and insecticide treated cattle (ITT/ITC) affected the feeding tsetse and other biting flies resulting in R0 < 1. The insecticide type, application timing and method, expertise and environmental conditions could affect the model stability. In areas with abundant biting flies and no tsetse flies, T. vivax showed R0 > 1 when infected wildlife hosts were present. High tsetse populations revealed R0 <1 for T. vivax when ITT and ITC were administered, either individually or together. Elimination of the transmitting vectors of AAT could cost a total of US$ 1,056,990 in southwest Nigeria. Hence, AAT in West Africa can only be controlled by strategically applying insecticides targeting all transmitting vectors, appropriate use of trypanocides, and institutionalising an appropriate barrier between the domestic and sylvatic areas.

An African Canine Trypanosomosis Case Import: Is There a Possibility of Creating a Secondary Focus of Trypanosoma congolense Infection in France?

African animal trypanosomosis are parasitic diseases caused by several protozoa of the genus Trypanosoma, transmitted by hematophagous insects, essentially tsetse flies, but also, less frequently by Tabanidae and Stomoxidae. They are geolocated in a part of the continent and affect livestock animals and carnivores; dogs are especially sensitive to them. They do not seem to present a zoonotic risk. Despite the chemical prevention with trypanocides for French military working dogs on mission in Côte d’Ivoire, a fatal case induced by Trypanosoma congolense in France after returning from Abidjan raises the question of an imported secondary focus. The clinical case was developed and the causative agent was confirmed by microscopy and PCR methods. The three necessary pillars to create a secondary potential focus are present: the parasite introduction in a new territory, the presence and the propagation vectors, and their proximity with sensitive species.

Gamma Irradiation and Male Glossina austeni Mating Performance

An area-wide integrated pest management (AW-IPM) strategy with a sterile insect technique (SIT) component has been proposed for the management of African animal trypanosomosis (AAT) in South Africa. In preparation for the SIT, the mating performance of colony reared Glossina austeni males under influencing factors such as radiation dose and the development stage that is exposed to radiation, was assessed under laboratory and semi-field conditions. The radiation sensitivity of G. austeni colonized 37 years ago when treated as adults and late-stage pupae was determined. Radiation doses of 80 Gy and 100 Gy induced 97–99% sterility in colony females that mated with colony males treated as adults or pupae. Males irradiated either as adults or pupae with a radiation dose of 100 Gy showed similar insemination ability and survival as untreated males. Walk-in field cage assessments indicated that a dose of up to 100 Gy did not adversely affect the mating performance of males irradiated as adults or late stage pupae. Males irradiated as adults formed mating pairs faster than fertile males and males irradiated as pupae. The mating performance studies indicated that the colonized G. austeni males irradiated as adults or late stage pupae will still be suited for SIT.