Shiferaw Jenberie

Capripox disease in Ethiopia: Genetic differences between field isolates and vaccine strain, and implications for vaccination failure

Sheeppox virus (SPPV), goatpox virus (GTPV) and lumpy skin disease virus (LSDV) of the genus Capripoxvirus (CaPV) cause capripox disease in sheep, goats and cattle, respectively. These viruses are not strictly host-specific and their geographical distribution is complex. In Ethiopia, where sheep, goats and cattle are all affected, a live attenuated vaccine strain (KS1-O180) is used for immunization of both small ruminants and cattle. Although occurrences of the disease in vaccinated cattle are frequently reported, information on the circulating isolates and their relation to the vaccine strain in use are still missing. The present study addressed the parameters associated with vaccination failure in Ethiopia. Retrospective outbreak data were compiled and isolates collected from thirteen outbreaks in small ruminants and cattle at various geographical locations and years were analyzed and compared to the vaccine strain. Isolates of GTPV and LSDV genotypes were responsible for the capripox outbreaks in small ruminants and cattle, respectively, while SPPV was absent. Pathogenic isolates collected from vaccinated cattle were identical to those from the non-vaccinated ones. The vaccine strain, genetically distinct from the outbreak isolates, was not responsible for these outbreaks. This study shows capripox to be highly significant in Ethiopia due to low performance of the local vaccine and insufficient vaccination coverage. The development of new, more efficient vaccine strains, a GTPV strain for small ruminants and a LSDV for cattle, is needed to promote the acceptance by farmers, thus contribute to better control of CaPVs in Ethiopia.

An international collaborative study to determine the prevalence of contagious caprine pleuropneumonia by monoclonal antibody-based cELISA

BackgroundFew serological tests are available for detecting antibodies against Mycoplasma capricolum subsp. capripneumoniae, the causal agent of contagious caprine pleuropneumonia (CCPP). The complement fixation test, the test prescribed for international trade purposes, uses a crude antigen that cross-reacts with all the other mycoplasma species of the “mycoides cluster” frequently infecting goat herds. The lack of a more specific test has been a real obstacle to the evaluation of the prevalence and economic impact of CCPP worldwide. A new competitive ELISA kit for CCPP, based on a previous blocking ELISA, was formatted at CIRAD and used to evaluate the prevalence of CCPP in some regions of Kenya, Ethiopia, Mauritius, Tajikistan and Pakistan in an international collaborative study.ResultsThe strict specificity of the test was confirmed in CCPP-free goat herds exposed to other mycoplasma species of the “mycoides cluster”. Prevalence studies were performed across the enzootic range of the disease in Africa and Asia. Seroprevalence was estimated at 14.6% in the Afar region of Ethiopia, whereas all the herds presented for CCPP vaccination in Kenya tested positive (individual seroprevalence varied from 6 to 90% within each herd). In Mauritius, where CCPP emerged in 2009, nine of 62 herds tested positive. In Central Asia, where the disease was confirmed only recently, no positive animals were detected in the Wakhan District of Afghanistan or across the border in neighboring areas of Tajikistan, whereas seroprevalence varied between 2.7% and 44.2% in the other districts investigated and in northern Pakistan. The test was also used to monitor seroconversion in vaccinated animals.ConclusionsThis newly formatted CCPP cELISA kit has retained the high specificity of the original kit. It can therefore be used to evaluate the prevalence of CCPP in countries or regions without vaccination programs. It could also be used to monitor the efficacy of vaccination campaigns as high-quality vaccines induce high rates of seroconversion.

Molecular characterization of orf virus from sheep and goats in Ethiopia, 2008–2013

BackgroundOrf is a contagious disease of sheep, goats and wild ungulates caused by orf virus (ORFV) a member of the genus Parapoxvirus, Poxviridae family. Although orf is endemic in Ethiopia, little attention has been given so far as it is not a notifiable disease by the World Organization for Animal Health. In this work, we have investigated orf outbreaks representing five different geographical locations of Ethiopia, in Amba Giorgis, Gondar zuria, Adet, Debre zeit and Adami Tulu, between 2008 and 2013.ResultsThe viral isolation and the sequence analysis of the A32L and the B2L genes of eighteen representative isolates confirmed that sampled animals were infected by ORFVs.The phylogenetic study and the comparative analysis of the deduced amino acid profile suggests that there were two main clusters of ORFV isolates which were responsible for the investigated outbreaks. Additionally the analysis of these two genes showed limited variability to ORFVs encountered elsewhere. This is the first report on the genetic characterization of the ORFV isolates from sheep and goats in Ethiopia.ConclusionThe molecular characterization of Ethiopian ORFV isolates highlighted the circulation of two main clusters causing orf disease in sheep and goats. The use of laboratory based methods and a constant monitoring of Ethiopian ORFV isolates is needed to better understand the dynamic of ORFV circulating in the country and facilitate the implementation of control measures.

Genetic characterisation of infectious bursal disease virus isolates in Ethiopia

Graphical abstract This paper describes a molecular characterisation of IBD circulating in commercial and breeding poultry farms in Ethiopia. Ethiopian vvIBDVs are clustered phylogenetically with the African IBDV genetic lineage, independent of the Asian/European genetic.

Outbreak investigation and molecular characterization of African horse sickness virus circulating in selected areas of Ethiopia.

The study was conducted from June 2011 to May 2012 in central, northern and western parts of Ethiopia to investigate and identify circulating serotypes of African horse sickness virus (AHSV). The indigenous knowledge of equine owners about AHS in the study areas was assessed and also the retrospective data of AHS outbreaks for 2011 were analyzed. Whole blood samples were collected for virus isolation and serotyping from diseased horses and mules showing typical signs of the AHS. Virus isolation on Vero cell and detection of AHSV genomes using conventional RT-PCR were conducted. Further molecular characterization and serotyping were done on positive isolates. The questionnaire survey revealed that equine owners do recognize AHS clinically and have a local name that varies in different regions. From the 72 equine owners interviewed about their knowhow of AHS, 48 (66.7%) of respondents were not aware of AHS disease mode of transmission. The retrospective disease report data showed that a total of 208 outbreaks were reported and 3036 cases and 1167 deaths were recorded in 2011. AHS outbreaks were more frequently observed from September to December and the highest number of outbreaks was recorded in October. During the study period totally six outbreaks were investigated and a total of 62 horses and 10 mules were found sick and all the four forms of AHS were observed. Cardiac form accounted for 52.8%, followed by African horse sickness fever form 31.9%, pulmonary form 8.4% and mixed form 6.9%. AHSV-9 was the only serotype circulating in the outbreak areas.

The first isolation and molecular characterization of camelpox virus in Ethiopia.

A cross-sectional study was conducted from November 2011 to April 2012 in Chifra district of Afar and in Jigjiga Zone of Somali Regional States of Ethiopia with the aims of assessing the epidemiology of camelpox and isolate and molecularly characterize the virus. The study included a questionnaire, active disease search and virus isolation and sequencing. A total of 24 (4.50%) and 12 (3.0%) camels in Afar and Jigjiga respectively were found clinically sick of camelpox during the study period. The questionnaire survey indicated that camelpox is the most common disease in the areas in which 125 (96%) of the respondents reported the frequent occurrence of camelpox in their herds especially during rainy season. The PCR result revealed 12 out of 17 tested samples were positive, of which seven of them collected from Jigjiga zone showed the characteristic PCR positive bands of 881 bp size fragments while five of the Afar samples gave two faint bands. Ethiopian isolates, specially isolated from Somali have very high identity with comparable sequences of CMLV M-96 from Kazakhstan and CMLV CMS from Iran. Out of the total of 780 bp analogous sequences, Ethiopian isolates differ only in two positions, while CMLV-Teheran differed at four nucleotide positions. The successfull isolation and molecular characterization of camelpox virus in Ethiopia, which could help for early diagnosis and control of the disease in the country.

Genetic characterization of poxviruses in Camelus dromedarius in Ethiopia, 2011-2014.

Camelpox and camel contagious ecthyma are infectious viral diseases of camelids caused by camelpox virus (CMLV) and camel contagious ecthyma virus (CCEV), respectively. Even though, in Ethiopia, pox disease has been creating significant economic losses in camel production, little is known on the responsible pathogens and their genetic diversity. Thus, the present study aimed at isolation, identification and genetic characterization of the causative viruses. Accordingly, clinical case observations, infectious virus isolation, and molecular and phylogenetic analysis of poxviruses infecting camels in three regions and six districts in the country, Afar (Chifra), Oromia (Arero, Miyu and Yabello) and Somali (Gursum and Jijiga) between 2011 and 2014 were undertaken. The full hemagglutinin (HA) and partial A-type inclusion protein (ATIP) genes of CMLV and full major envelope protein (B2L) gene of CCEV of Ethiopian isolates were sequenced, analyzed and compared among each other and to foreign isolates. The viral isolation confirmed the presence of infectious poxviruses. The preliminary screening by PCR showed 27 CMLVs and 20 CCEVs. The sequence analyses showed that the HA and ATIP gene sequences are highly conserved within the local isolates of CMLVs, and formed a single cluster together with isolates from Somalia and Syria. Unlike CMLVs, the B2L gene analysis of Ethiopian CCEV showed few genetic variations. The phylogenetic analysis revealed three clusters of CCEV in Ethiopia with the isolates clustering according to their geographical origins. To our knowledge, this is the first report indicating the existence of CCEV in Ethiopia where camel contagious ecthyma was misdiagnosed as camelpox. Additionally, this study has also disclosed the existence of co-infections with CMLV and CCEV. A comprehensive characterization of poxviruses affecting camels in Ethiopia and the full genome sequencing of representative isolates are recommended to better understand the dynamics of pox diseases of camels and to assist in the implementation of more efficient control measures.

First confirmation of foot and mouth disease virus serotype SAT-1 in cattle and small ruminants in Ethiopia in 2007/08.

The study was conducted in three regional states of Ethiopia: Amhara, Oromia, and the Southern Nations Nationalities and people regional state from August 2007 to April 2008 with the objective of identifying the foot and mouth disease virus (FMDV) serotypes circulating in the region. Two serotypes were recorded from epithelial tissue and oesophageal–pharyngeal (OP) fluid that were taken from outbreaks in study regions of Ethiopia. Serotype O FMDV was identified in Girar Jarso, Yabello, and Ankesha Guagusa districts while SAT-1 was isolated in Surma and Maji districts from tissue samples and this was the first report of the FMDV serotype in Ethiopia. Similarly, the OP fluid samples were found positive for SAT-1 FMDV in Maji and Surma districts.

Investigation of respiratory viruses in camel slaughtered at Addis Ababa Akaki Abattoir, Ethiopia

Camel is an important domestic animal uniquely adapted to the hot and arid environment, but its contribution to Ethiopian pastoralists is disproportionate to its resource potential due to the presence of various infectious and parasitic diseases in the area. Therefore this study was conducted with an attempt to isolate and characterize respiratory viruses from infected lungs. Accordingly, camel lung tissues were collected from Akaki abattoir and transported to National Veterinary Institute virology laboratory and stored temporarily at -85°C. The samples were processed and inoculated on confluent VERO cells, incubated at 37°C and examined for the development of cytopathogenic effect (CPE) for 4 to 15 days. From thirty five examined samples twenty seven were CPE positive. Ten supernatant samples exhibiting CPE were taken and tested for presence of both DNA and RNA viruses, using universal degenerate oligonucleotide primed– polymerase chain reaction (DOP-PCR) and conventional polymerase chain reaction (PCR) techniques. Five out of six samples tested by DOP-PCR were positive for presence of RNA virus, while only one sample was positive for DNA virus. Nine of ten samples were positive for, Respiratory syncytial virus (RSV) and two of six were positive for Adenovirus , but all tested samples were negative for Peste Des Petits Ruminants Virus (PPRV) and Parainfluenza viruses 1-3.

RETRACTED: Sequence variability in the structural protein-encoding region of foot-and-mouth disease virus serotype A and O of Ethiopian isolates

A total of 13 serotype O and 5 serotype A FMD Ethiopian isolates and some isolates from other countries (six for serotype A and four for serotype O) were sequenced on the structural protein (P1) coding region. The deduced amino acid sequences were aligned and investigated in an attempt to determine the amino acid variation. Differences were observed at 115 (15.6%) and 119 (16.1%) amino acid positions for serotype O and serotype A, respectively. The variation in the derived amino acid sequences is the highest in VP1, while VP4 was highly conserved in both serotypes A and O. In all isolates, hypervariable regions were located at regions corresponding to the highly immunogenic sites, the G-H loop (133-158) and the C-terminus (194-213) of the VP1 gene. The RGD cell attachment site within the G-H loop of the gene was conserved in all isolates. The study revealed the presence of significant amino acid variation at VP2 and VP3 in addition to known VP1 coding region. Hence, determination of amino acid sequence of the whole P1 region provides more information on antigenic variability of FMD virus and could be used in vaccine strain selection in parallel with serological vaccine matching assays.