Molecular detection and phylogenetic analysis of lumpy skin disease virus from outbreaks in Uganda 2017-2018.

BACKGROUND: Lumpy skin disease (LSD) is an infectious viral disease of cattle caused by a Capripoxvirus. LSD has substantial economic implications, with infection resulting in permanent damage to the skin of affected animals which lowers their commercial value. In Uganda, LSD is endemic and cases of the disease are frequently reported to government authorities. This study was undertaken to molecularly characterize lumpy skin disease virus (LSDV) strains that have been circulating in Uganda between 2017 and 2018. Secondly, the study aimed to determine the phylogenetic relatedness of Ugandan LSDV sequences with published sequences, available in GenBank. RESULTS: A total of 7 blood samples and 16 skin nodule biopsies were screened for LSDV using PCR to confirm presence of LSDV nucleic acids. PCR positive samples were then characterised by amplifying the GPCR gene. These amplified genes were sequenced and phylogenetic trees were constructed. Out of the 23 samples analysed, 15 were positive for LSDV by PCR (65.2%). The LSDV GPCR sequences analysed contained the unique signatures of LSDV (A11, T12, T34, S99, and P199) which further confirmed their identity. Sequence comparison with vaccine strains revealed a 12 bp deletion unique to Ugandan outbreak strains. Phylogenetic analysis indicated that the LSDV sequences from this study clustered closely with sequences from neighboring East African countries and with LSDV strains from recent outbreaks in Europe. It was noted that the sequence diversity amongst LSDV strains from Africa was higher than diversity from Eurasia. CONCLUSION: The LSDV strains circulating in Uganda were closely related with sequences from neighboring African countries and from Eurasia. Comparison of the GPCR gene showed that outbreak strains differed from vaccine strains. This information is necessary to understand LSDV molecular epidemiology and to contribute knowledge towards the development of control strategies by the Government of Uganda.

Serological and clinical evaluation of the Yugoslavian RM65 sheep pox strain vaccine use in cattle against lumpy skin disease.

Lumpy skin disease (LSD) is an emerging infectious disease of cattle. Since 2012, it has been seen throughout the Middle East region. The aim of this study was to compare the humoral response of three different dosages of the RM65 sheep pox (SPP) vaccine to assess the use of ten times sheep dose of the RM65 vaccine against lumpy skin disease, and to explore the possible causes of, and characterize the side effects caused by the RM65 vaccine. A blinded randomized collected study comprised 57 clinically normal, Holstein Friesian cattle which were randomly assigned into three experimental groups of 17 cattle according to the vaccine dose used (one, five and ten times the dose used for sheep in the field, and a control group of six cattle that did not receive the vaccine. Experimental animals were monitored closely for the development of any abnormality or side effects. Serum samples were collected for 6 weeks and were tested using serum neutralization assay. Decrease in total milk production was observed a week after vaccination and by the fifth week of the experiment, it had returned to prevaccination levels. Clinical side effects were seen in five animals that belong only to the group that received ten times of the SPP vaccine dose. Observed side effects included fever, decreased feed intake and milk production, as well as skin lesions. Skin nodules appeared between 7 and 17 days postvaccination, and remained for 11-17 days. Systemic reactions were likely to be associated with higher dosage and all affected cattle recovered uneventfully. Animals that received the highest dose (ten times the sheep dose) showed the best humoral response. The actual efficacy of the different concentration of the SPP RM65 should be evaluated based on a challenge experiment in a controlled environment.

Clinical, hematologic, and biochemical findings in cattle infected with lumpy skin disease during an outbreak in southwest Iran.

This study was performed to determine the clinical, hematologic, and biochemical findings in animals affected with lumpy skin disease (LSD) in southwest Iran. Sixty cattle with LSD were included in this study and compared with 20 healthy ones as the control group. The disease was diagnosed based on clinical examination and confirmed by polymerase chain reaction analysis of the blood samples. The major observed clinical signs included skin nodules, fever, enlarged lymph nodes, and edema. In hematologic assessment, the average numbers of leukocytes, lymphocytes, eosinophils, erythrocytes, and platelets, as well as the average level of hemoglobin in the infected animals were significantly lower than in the control group. Biochemical experiments showed that the serum glucose, total and direct bilirubin, aspartate aminotransferase, and creatine phosphokinase activities in the infected group were significantly elevated. LSD also caused a significant reduction in the levels of serum creatinine, albumin, and iron. In total, LSD was associated with an overall decline in different blood cell types and significant changes in serum biochemical profile. These alterations could be related to the inflammatory disease processes and injuries in various organs, especially the liver. Hematologic and biochemical profiles can be utilized to better understand different aspects of LSD pathogenesis and ultimately improve its prognostic, management, and treatment methods.

Serum Biochemistry of Lumpy Skin Disease Virus-Infected Cattle.

Lumpy skin disease is an economically important poxvirus disease of cattle. Vaccination is the main method of control but sporadic outbreaks have been reported in Turkey. This study was carried out to determine the changes in serum biochemical values of cattle naturally infected with lumpy skin disease virus (LSDV). For this study, blood samples in EDTA, serum samples, and nodular skin lesions were obtained from clinically infected animals (n = 15) whereas blood samples in EDTA and serum samples were collected from healthy animals (n = 15). A quantitative real-time PCR method was used to detect Capripoxvirus (CaPV) DNA in clinical samples. A real-time PCR high-resolution melt assay was performed to genotype CaPVs. Serum cardiac, hepatic, and renal damage markers and lipid metabolism products were measured by autoanalyzer. LSDV nucleic acid was detected in all samples which were obtained from clinically infected cattle. The results of serum biochemical analysis showed that aspartate aminotransferase, alkaline phosphatase, total protein, and creatinine concentrations were markedly increased in serum from infected animals. However, there were no significant differences in the other biochemical parameters evaluated. The results of the current study suggest that liver and kidney failures occur during LSDV infection. These findings may help in developing effective treatment strategies in LSDV infection.

Mechanical transmission of lumpy skin disease virus by Rhipicephalus appendiculatus male ticks.

Lumpy skin disease (LSD) is an economically important, acute or sub-acute, viral disease of cattle that occurs across Africa and in the Middle East. The aim of this study was to investigate if lumpy skin disease virus (LSDV) can be transmitted mechanically by African brown ear ticks (Rhipicephalus appendiculatus Neum.). Laboratory-bred R. appendiculatus males were fed on experimentally infected viraemic 'donor' cattle. Partially fed male ticks were then transferred to feed on an uninfected 'recipient' cow. The recipient animal became viraemic, showed mild clinical signs of LSD and seroconverted. Additionally, R. appendiculatus males were found to transmit LSDV through feeding on skin lacking visible lesions, demonstrating that viraemic animals without lesions at the feeding site of ticks may be a source of infection. This is the first time that transmission of poxviruses by a tick species has been demonstrated and the importance of this mode of transmission in the spread of LSDV in endemic settings is discussed.

The detection of lumpy skin disease virus in samples of experimentally infected cattle using different diagnostic techniques.

Lumpy skin disease (LSD) is a disease of cattle, primarily in Africa and Madagascar and rarely in the Middle East. It is caused by a capripoxvirus that belongs to the family Poxviridae. The disease is of economic importance in endemic areas. Effective control of LSD requires accurate and rapid laboratory techniques to confirm a tentative clinical diagnosis. Comparative studies on different diagnostic tests used at different stages of the disease have not been done. The aim of this study was to compare several of these tests. Six seronegative bulls, between 11 and 20 months of age, were infected intravenously and kept in an insect-free facility. The course of the infection was monitored. During a 3-month period blood samples and skin biopsies were collected for virus isolation and polymerase chain reaction (PCR). Skin biopsies were also examined using transmission electron microscopy (TEM). The incubation period in infected animals varied from 4-5 days. The length of the viraemic period did not correlate with the severity of clinical disease. Viraemia was detected from 1-12 days using virus isolation and from 4-11 days using the PCR, which is longer than has previously been reported. Virus was isolated from skin biopsies until Day 39 post infection (p.i.) and PCR could demonstrate viral DNA until Day 92 p.i. Transmission electron microscopy of negatively stained skin biopsies detected LSD virus only in one of the four bulls that developed skin lesions until Day 33 p.i. The PCR was a fast and sensitive method to demonstrate viral DNA in blood and skin samples. It could detect viral nucleic acid in skin lesions 53 days longer than virus isolation. Virus isolation from blood and skin samples was sensitive and reliable, but as a single test it may be too time-consuming to use although this depends on how rapidly the diagnosis must be confirmed. In conclusion, this study showed the PCR to be superior in detecting LSD virus from blood and skin samples. However, virus isolation is still required when the infectivity of the LSD virus is to be determined.