Direct detection and characterization of foot-and-mouth disease virus in East Africa using a field-ready real-time PCR platform

Effective control and monitoring of foot-and-mouth disease (FMD) relies upon rapid and accurate disease confirmation. Currently, clinical samples are usually tested in reference laboratories using standardized assays recommended by The World Organisation for Animal Health (OIE). However, the requirements for prompt and serotype-specific diagnosis during FMD outbreaks, and the need to establish robust laboratory testing capacity in FMD-endemic countries have motivated the development of simple diagnostic platforms to support local decision-making. Using a portable thermocycler, the T-COR™ 8, this study describes the laboratory and field evaluation of a commercially available, lyophilized pan-serotype-specific real-time RT-PCR (rRT-PCR) assay and a newly available FMD virus (FMDV) typing assay (East Africa-specific for serotypes: O, A, Southern African Territories [SAT] 1 and 2). Analytical sensitivity, diagnostic sensitivity and specificity of the pan-serotype-specific lyophilized assay were comparable to that of an OIE-recommended laboratory-based rRT-PCR (determined using a panel of 57 FMDV-positive samples and six non-FMDV vesicular disease samples for differential diagnosis). The FMDV-typing assay was able to correctly identify the serotype of 33/36 FMDV-positive samples (no cross-reactivity between serotypes was evident). Furthermore, the assays were able to accurately detect and type FMDV RNA in multiple sample types, including epithelial tissue suspensions, serum, oesophageal–pharyngeal (OP) fluid and oral swabs, both with and without the use of nucleic acid extraction. When deployed in laboratory and field settings in Tanzania, Kenya and Ethiopia, both assays reliably detected and serotyped FMDV RNA in samples (n = 144) collected from pre-clinical, clinical and clinically recovered cattle. These data support the use of field-ready rRT-PCR platforms in endemic settings for simple, highly sensitive and rapid detection and/or characterization of FMDV

Molecular characterization of infectious bursal disease virus detected in Morogoro, Tanzania

Proceeding of the scientific conference of theTanzania veterinary Association, Volume 35: 30-36Infectious bursal disease (IBD) virus (IBDV) is a double-stranded RNA virus that belongs to the genus Avibirnavirus of the family Birnaviridae. IBDV is a causative agent of IBD, the highly contagious viral infection of young chickens aged 3 to 6 weeks. IBD outbreaks occur frequently in both vaccinated and non-vaccinated chickens in Tanzania causing significant economic loss among poultry keepers. The control of IBD is mainly done through vaccination, which requires the understanding of molecular and biological characteristics of circulating virus strains in particular geographic location. This study was conducted to determine the genotype of IBDV recovered from confirmed IBD outbreak(s) in 2014 in Morogoro, Tanzania. The investigation was performed by reverse-transcription polymerase chain reaction (RT-PCR), sequencing and phylogeny analysis of nucleotide sequences corresponding to the VP2 hypervariable (VP2-HVR) domain of IBDV. The findings indicated 100% detection rate (n = 10) of IBDV genome from infected bursa of Fabricius samples. Phylogenetic analysis revealed that the sequenced virus belonged to the African very virulent IBDV (VV- IBDV) genotype and was genetically closely related to KZC-109 strain detected in Zambia in 2004. Taken together, our findings suggest that the African VV-IBDV detected in this study was responsible for the IBD outbreak(s) in Morogoro. Further studies are required to examine the transmission dynamics, evolutionary characteristics and antigenicity of field IBDV strains order to design the appropriate control method(s) of IBD in Tanzania and neighboring countries

Molecular characterization of infectious bursal disease virus detected in Morogoro, Tanzania

Proceeding of the scientific conference of theTanzania veterinary Association, Volume 35: 30-36Infectious bursal disease (IBD) virus (IBDV) is a double-stranded RNA virus that belongs to the genus Avibirnavirus of the family Birnaviridae. IBDV is a causative agent of IBD, the highly contagious viral infection of young chickens aged 3 to 6 weeks. IBD outbreaks occur frequently in both vaccinated and non-vaccinated chickens in Tanzania causing significant economic loss among poultry keepers. The control of IBD is mainly done through vaccination, which requires the understanding of molecular and biological characteristics of circulating virus strains in particular geographic location. This study was conducted to determine the genotype of IBDV recovered from confirmed IBD outbreak(s) in 2014 in Morogoro, Tanzania. The investigation was performed by reverse-transcription polymerase chain reaction (RT-PCR), sequencing and phylogeny analysis of nucleotide sequences corresponding to the VP2 hypervariable (VP2-HVR) domain of IBDV. The findings indicated 100% detection rate (n = 10) of IBDV genome from infected bursa of Fabricius samples. Phylogenetic analysis revealed that the sequenced virus belonged to the African very virulent IBDV (VV- IBDV) genotype and was genetically closely related to KZC-109 strain detected in Zambia in 2004. Taken together, our findings suggest that the African VV-IBDV detected in this study was responsible for the IBD outbreak(s) in Morogoro. Further studies are required to examine the transmission dynamics, evolutionary characteristics and antigenicity of field IBDV strains order to design the appropriate control method(s) of IBD in Tanzania and neighboring countries

Plasma drug activity assay for treatment optimization in tuberculosis patients

Item does not contain fulltextLow antituberculosis (TB) drug levels are common, but their clinical significance remains unclear, and methods of measurement are resource intensive. Subjects initiating treatment for sputum smear-positive pulmonary TB were enrolled from Kibong'oto National TB Hospital, Tanzania, and levels of isoniazid, rifampin, ethambutol, and pyrazinamide were measured at the time of typical peak plasma concentration (C(2 h)). To evaluate the significance of the effect of observed drug levels on Mycobacterium tuberculosis growth, a plasma TB drug activity (TDA) assay was developed using the Bactec MGIT system. Time to detection of plasma-cocultured M. tuberculosis versus time to detection of control growth was defined as a TDA ratio. TDA assays were later performed using the subject's own M. tuberculosis isolate and C(2 h) plasma from the Tanzanian cohort and compared to drug levels and clinical outcomes. Sixteen subjects with a mean age of 37.8 years +/- 10.7 were enrolled. Fourteen (88%) had C(2 h) rifampin levels and 11 (69%) had isoniazid levels below 90% of the lower limit of the expected range. Plasma spiked with various concentrations of antituberculosis medications found TDA assay results to be unaffected by ethambutol or pyrazinamide. Yet with a range of isoniazid and rifampin concentrations, TDA exhibited a statistically significant correlation with drug level and drug MIC, and a TDA of approximately 1.0 indicated the presence of multidrug-resistant TB. In Tanzania, low (</=2.0) TDA was significantly associated with both lower isoniazid and rifampin C(2 h) levels, and very low (</=1.5) TDA corresponded to a trend toward lack of cure. Study of TDA compared to additional clinical outcomes and as a therapeutic management tool is warranted