Phylogenetic analysis of the lumpy skin disease viruses in northwest of Iran

Lumpy skin disease (LSD) is a devastating viral disease of cattle which has recently spread from Africa into the countries of the Middle East. The aim of the present study was to investigate the relationships among lumpy skin disease viruses (LSDV) isolated from different regions of Iran and the origin and spread of these viruses. In this study, a total of 234 blood samples from clinically affected animals from four provinces in the northwest of Iran were screened for LSDV using polymerase chain reaction (PCR). From 80 positive samples for LSDV detected by PCR, the partial P32 gene (759 bp) of 12 isolates were sequenced and phylogenetically analyzed. LSD viruses were grouped in three subclusters with an overall 97.1–100% nucleotide identity. LSDVs isolated from Gilan showed lowest nucleotide identity with the other LSDVs. Four isolates of LSDV including KO-1, EA-1, EA-3, and WA-3 showed 100% similarity with each other and also with the Neethling strain. Phylogenetic analysis indicated that the identified LSDVs were closely related to each other and had high-sequence homology with other LSDV isolates from Africa. It was concluded that LSD outbreak probably occurred in the northwest of Iran by LSDVs entering the country from Iraq and P32 nucleotide sequence information obtained in the present study is a valuable resource in understanding the genetic nature and molecular epidemiology of local LSDV isolates which can be used for future vaccine development based on the circulating strains in the region.     

疙瘩皮肤病概述

疙瘩皮肤病(LSD)又称结节性皮炎或块状皮肤病,是世界动物卫生组织(OIE)规定的A类疫病之一。LSD是由LSDV引起的,以发热,皮肤、粘膜、器官表面广泛性结节,消瘦,淋巴结肿大,皮肤水肿为特征,严重时会引起死亡。此病能大幅度降低产乳量,损坏皮张,常带来较大的经济损失。目前,此病在非洲、以色列等国家和地区发生流行,我国尚无此类疫病的发生。本文仅就疙瘩皮肤病的病原、流行病学、临床与病理、诊断、预防及控制等方面作一概述。     

The isolation of lumpy skin disease virus and bovine herpesvirus-4 from cattle in Egypt

Lumpy skin disease (LSD) virus (LSDV) was isolated for the first time from cattle in Egypt in 2 disease outbreaks. Bovine herpesvirus-4 (BHV-4) and LSDV were detected in a pooled sample from the first outbreak (Suez). Only LSDV was isolated from the second outbreak (Ismalia). The capripoxviruses were identified as LSDV by neutralization with specific antiserum and by their ability to produce generalized LSD in experimentally inoculated cattle.     

Molecular characterization and phylogenetic analysis of lumpy skin disease in Egypt

Lumpy skin disease (LSD) is an infectious viral disease affecting cattle, cause severe economic losses. In the last few years, the disease is widely distributed in many countries in the Middle East, including Egypt. This study aimed to determine the genetic character of LSDV circulating in some governorates in Egypt and its relation with other LSDVs and vaccine strains in GenBank. A total of 50 skin nodules and 50 blood samples were collected from clinically affected cattle to detect LSDV using PCR targeting the P32 gene. The positive samples were characterized using PCR targeting the GPCR gene. The amplified products of four samples detected in the skin nodule of cattle from Alexandria and Kafr ElSheikh governorates were sequenced, and the phylogenetic tree was constructed. Out of 100 analyzed samples, 70 samples were positive for LSDV by PCR assay. In addition, the sequence alignment of the obtained LSDV strains detected in the Alexandria governorate showed high similarity to the LSDV genome (MN995838). In contrast, LSDV strains from Kafr ElSheikh governorate revealed high similarity and the previous Egyptian strain (MG970343), which was isolated from cattle in Sharkia governorate in 2016. Also, the phylogenetic analysis confirmed that one of the LSDV strain (LC601598) from Alexandria is closely related to the LSDV of Menofia/Egypt/2019 (MN271722), while another one (LC601597) is closely related to vaccine strains of LSDV. Moreover, the LSDV strains from Kafr Elsheikh showed closely related to previous LSDV strains isolated from Menofia (MG970343) and Dakahlia (KP071936) governorates and clustered with other LSDV strains in a distinct cluster. This information is for understanding the epidemiology of LSDV and supporting the establishment of an efficient control program for the disease.     

Epidemiological aspects and financial impact of lumpy skin disease in Ethiopia

The financial cost of clinical Lumpy Skin Disease (LSD) and the financial benefit of its control through vaccination were studied based on questionnaire survey in Oromia region of Ethiopia from the perspective of livestock farmers. Production loss impacts for local zebu cattle were compared with those of Holstein Friesian (HF)/crossbred cattle in the study area. Annual cumulative incidence of LSD infection in HF/crossbred and local zebu cattle were 33.93% (95% CI: 30.92-36.94) and 13.41% (95% CI: 12.6-14.25) respectively and significantly different (p<0.05). Annual mortality was also significantly higher in HF/crossbred 7.43% (95% CI: 5.76-9.10) than in local zebu cattle 1.25% (95% CI: 0.98-1.52). The annual financial cost was calculated as the sum of the average production losses due to morbidity and mortality arising from milk loss, beef loss, traction power loss, and treatment and vaccination costs at the herd level. The financial cost in infected herds was estimated to be USD 6.43 (5.12-8) per head for local zebu and USD 58 (42-73) per head for HF/crossbred cattle. A partial budget analysis was used to estimate the financial benefit of an annual vaccination program in both the local zebu and HF/crossbred cattle farming systems. The marginal rate of return (MRR) gained from this control intervention was estimated to be 34 (3400%) and the net benefit per head was USD 1 for local zebu and USD 19 for HF/crossbred cattle. Vaccination thus enabled financial costs due to LSD to be reduced by 17% per head in local zebu herds and 31% per head in HF/crossbred herds. These results could provide guidance to producers and the government in their endeavors to control the disease.     

Alternative cell lines for the propagation of lumpy skin disease virus

In our Institute lumpy skin disease virus is grown on primary lamb testis cells for isolation, identification and vaccine production. However, the availability of lambs in Kenya has been seriously reduced over the past few years. This has led to an increase in the cost of using primary lamb testis cells. This study was undertaken to investigate other primary cell lines, which are easily available and provide an equivalent or better yield of lumpy skin disease virus. Foetal bovine muscle (FBM) cells were found to be an adequate alternative for lamb testis cells.     

Elimination of toxicity and enhanced detection of lumpy skin disease virus on cell culture from experimentally infected bovine semen samples

Lumpy skin disease virus (LSDV), a poxvirus of the genus Capripoxvirus, is shed in the semen of infected bulls. The screening of semen for infectious virus requires a sensitive diagnostic method. The isolation of the virus on cell cultures and/or the polymerase chain reaction (PCR) are sensitive diagnostic tests which may be used to screen semen for LSD viral DNA prior to artificial insemination. Although cell culture detects infectious virus and is a sensitive method, there are major difficulties in using this method due to the toxic effect of semen on the cells. The aim of this study was to find a method that decreases the toxic effect of semen and enhances the isolation of LSDV on cell culture. Semen samples from LSDV sero-negative bulls were collected and infected with a field isolate of LSDV, strain V248/93, with a titre of 6.5 log TCID50. The semen samples were treated with one of four different methods: centrifugation, serial dilution, filtration and chemical treatment with kaolin. The samples subjected to centrifugation, serial dilution and filtration were supplemented with gentamycin. Semen toxicity on cell cultures was eliminated when supernatants of semen samples centrifuged at 2000 rpm for 1, 3 and 5 min and serially diluted were used to inoculate confluent monolayer bovine dermis cells. The toxicity recorded when the pellet fractions of semen samples centrifuged for 5 min at 2000 rpm was comparable to results obtained from serially diluted samples supplemented with gentamycin. Filtration and kaolin treatment of semen samples did not remove the toxic effect.     

Long-term changes in the spatial distribution of lumpy skin disease hotspots in Zimbabwe

Tropical Animal Health and Production - Outbreaks of lumpy skin disease (LSD) are reported almost every year in Zimbabwe but not much is known regarding whether the pattern of the disease is...     

Mathematical modelling and evaluation of the different routes of transmission of lumpy skin disease virus

ABSTRACT: Lumpy skin disease (LSD) is a severe viral disease of cattle. Circumstantial evidence suggests that the virus is transmitted mechanically by blood-feeding arthropods. We compared the importance of transmission via direct and indirect contact in field conditions by using mathematical tools. We analyzed a dataset collected during the LSD outbreak in 2006 in a large dairy herd, which included ten separated cattle groups. Outbreak dynamics and risk factors for LSD were assessed by a transmission model. Transmission by three contact modes was modelled; indirect contact between the groups within a herd, direct contact or contact via common drinking water within the groups and transmission by contact during milking procedure. Indirect transmission was the only parameter that could solely explain the entire outbreak dynamics and was estimated to have an overall effect that was over 5 times larger than all other possible routes of transmission, combined. The R0 value induced by indirect transmission per the presence of an infectious cow for 1 day in the herd was 15.7, while the R0 induced by direct transmission was 0.36. Sensitivity analysis showed that this result is robust to a wide range of assumptions regarding mean and standard deviation of incubation period and regarding the existence of sub-clinically infected cattle. These results indicate that LSD virus spread within the affected herd could hardly be attributed to direct contact between cattle or contact through the milking procedure. It is therefore concluded that transmission mostly occurs by indirect contact, probably by flying, blood-sucking insects. This has important implications for control of LSD.