lumpy skin disease virus

Preferred Scientific Name

• lumpy skin disease virus

International Common Names

• English: Neethling virus

English acronym

• LSDV

• Domain: Virus
•     Group: "ssDNA viruses"
•         Group: "DNA viruses"
•             Family: Poxviridae
•                 Subfamily: Chordopoxvirinae
•                     Genus: Capripoxvirus
•                         Species: lumpy skin disease virus

Lumpy skin disease virus (LSDV) is a member of the genus Capripoxvirus in the family Poxviridae. It is closely related to the other two capripoxviruses Sheeppox virus and Goatpox virus. The three viruses can be distinguished by genome analysis, but cannot be differentiated serologically (OIE, 2017). The 151-kbp LSDV genome consists of a central coding region bounded by identical 2.4 kbp-inverted terminal repeats and contains 156 putative genes (Tulman et al., 2001).

The early studies in South Africa showed that a transmissible agent was involved in the aetiology of lumpy skin disease (LSD), and that it was not due to an allergic response to insect bites. However, early attempts to isolate the virus in tissue cultures were complicated by the isolation of three different virus groups from tissues that were taken from lesion samples. Firstly researchers isolated a herpes virus, which was subsequently shown to be bovine herpes virus group 2, subsequently known to cause Allerton or pseudo lumpy skin disease. On sub-inoculation into cattle, it produces an initial reaction, which for 1-2 days resembles that produced by LSD. This is a focal inflammation of the skin, which after 3-4 days rapidly becomes necrotic only in the very superficial epidermal and dermal layers (Alexander et al.,1957); the same virus causes bovine herpes mammilitis, which is a similar superficial necrotic disease affecting mainly the udder (Gibbs and Rweyemamu, 1977). A second herpes virus was isolated which belonged to the orphan herpes virus group 3. These are regularly isolated from the skin and other tissues of cattle and are not known to be associated with any disease problem. They do mislead diagnosticians however, who find herpes virus particles in LSD skin lesions (House et al., 1990).

A third virus isolate from the LSD lesions proved to be the one that reproduced the disease upon sub-inoculation into cattle. This was a poxvirus whose morphology and other characteristics suggested that it might be an orthopox virus. Further tests showed that the LSD virus was serologically and immunologically virtually identical with sheep and goat poxviruses of the Capripox genus (Alexander et al., 1957; Haig, 1957; Davies et al., 1971: Davies and Atema, 1981).

Capripox virus particles are ovoid in shape and both LSD and the sheep and goat isolates appear to be of similar size; 294 nm long and 262 nm wide with standard deviations of approximately +/- 20 nm. They have double stranded DNA and appear in forms covered by a membrane or mulberry-like components, similar to those described for members of the Orthopox viruses, which they closely resemble (Munz and Owen, 1966). The core has a characteristic dumbbell shape. The virus is ether- and chloroform-sensitive, it loses infectivity after 1 h at 60°C, is sensitive to sodium desoxycholate, losing infectivity after 1 h and is acid sensitive (Weiss, 1968). The virus, like most poxviruses, is stable over a wide range of temperatures and is highly resistant to desiccation in the presence of proteinaceous material. LSDV can survive for long periods at ambient temperature, especially in dried scabs. LSDV is very resistant to inactivation, surviving in necrotic skin nodules for up to 33 days or longer, desiccated crusts for up to 35 days, and at least 18 days in air-dried hides. It can remain viable for long periods in the environment. The virus is susceptible to sunlight and detergents containing lipid solvents, but in dark environmental conditions, such as contaminated animal sheds, it can persist for many months (OIE, 2017).

Strain variation

All strains that have been isolated are serologically and immunologically identical. All Capripox viruses are very closely related with 95.8% homology of the nucleotide sequences, but LSD is most closely allied to the African group of Capripox viruses, which include the sheep and goat poxviruses found in Africa. Other groups are from sheep or goats in other parts of the world and from either sheep or goats in Africa and the Middle East (Kitching et al., 1989). LSD virus is virtually indistinguishable from the African sheeppox and goatpox strains other than by its level of host adaptation in producing clinical LSD in cattle (Davies and Atema, 1981).

All the natural strains of LSDV that have been isolated have been pathogenic, and no naturally occurring strains with modified virulence have been found. A strain from South Africa has been found to have greatly reduced virulence after 60 passages in tissue cultures and then 20 times in embryonated eggs. It is immunogenic and is extensively used as a vaccine despite the fact that it produces a granulomatous reaction at the site of inoculation (Weiss, 1968). A Kenyan LSDV strain showed no modification of virulence after 70 passages in a foetal muscle cell line. 

Lumpy skin disease is on the list of diseases notifiable to the World Organisation for Animal Health (OIE). The distribution section contains data from OIE's Handistatus database on disease occurrence. For recent, detailed information on the occurrence of this disease worldwide, see the OIE World Animal Health Information Database (WAHIS) Interface.