Lumpy Skin Disease Classification

The virus that causes lumpy skin disease (LSDV) has double-stranded DNA. It belongs to the family Poxviridae and the genus Capripoxvirus. Within the subfamily of Chordopoxviruses (ChPVs), Capripoxviruses (CaPVs) are one of eight genera. Along with LSDV, sheeppox and goatpox viruses make up the capripoxvirus genus. Even while CaPV infections are serologically identical, they typically have host specificity within particular geographic distributions.

Structure

Capripoxviruses have a brick-like form like other members of the Poxviridae family. In addition to having a more oval profile and larger lateral bodies, capripoxvirus virions differ from orthopoxvirus virions in this regard. Capripoxvirions typically measure 320 by 260 nanometers.

Genome

The virus has a 151-kbp genome that is made up of 156 genes and a core coding region that is surrounded by identical 2.4 kbp-inverted terminal repeats. When LSDV is compared to chordopoxviruses from other genera, 146 genes are conserved. These genes produce proteins that are essential for virion structure and assembly, transcription and mRNA biogenesis, nucleotide metabolism, DNA replication, protein processing, viral pathogenicity, and host range. The genes of other mammalian poxviruses and the genes of LSDV exhibit significant collinearity and amino acid identity within the central genomic region. Suipoxvirus, Yatapoxvirus, and Leporipoxvirus are a few examples of viruses with a similar amino acid identity. However, collinearity is broken at terminal regions.

Poxvirus homologues are either absent or share a lower level of amino acid identity in these areas. The majority of these genetic variations are probably linked to genes that affect viral virulence and host range. Interleukin-10 (IL-10) homologues, IL-1 binding proteins, G protein-coupled CC chemokine receptors, and epidermal growth factor-like protein are all identified in LSDV, which is specific to the Chordopoxviridae family of poxviruses.

Epidemiology

Giraffes, water buffalo, and impalas have all been reported to have LSDV, which primarily affects cattle and zebu animals. The disease is especially contagious in fine-skinned Bos taurus cow breeds like Holstein-Friesian and Jersey. Breeds of the Bos indicus with thick skin, such as the Afrikaner and Afrikaner crossbreeds, exhibit less severe illness symptoms.

This is possibly because Bos indicus breeds are less susceptible to ectoparasites than Bos taurus breeds are. Although all age groups are susceptible to the disease, young calves and cows in their prime lactation have more severe clinical signs.

 

Transmission

Excessive temperatures and high humidity are linked to LSDV outbreaks. However, outbreaks can also happen in the dry season. It is typically more common in low-lying places or close to water during the wet summer and fall months. Insects that feed on blood, including flies and mosquitoes, serve as mechanical carriers for the disease. There isn’t a single species of vector known. Instead, the virus has been isolated from the species of Culicoides, Tabanidae, Glossina, Biomyia fasciata, and Stomoxys.

It is still being determined how each of these insects specifically contributes to LSDV transmission. Lumpy skin disease outbreaks are typically sporadic because the vector populations are influenced by animal movements, immunological condition, and wind and rainfall patterns.

The virus can spread through saliva, semen, nasal discharge, lacrimal secretions, and blood. Suckling calves can also contract the illness from milk that has been contaminated. LSDV was discovered in saliva 11 days after the onset of fever in experimentally infected calves, in semen 22 days later, and in skin nodules 33 days later. Urine or faeces do not contain the virus.

The LSDV can persist infected tissue for more than 120 days, just like other pox viruses, which are well known for being very resistant.

 

Immunity

Artificial defences

There have been two alternative methods for LSDV vaccination. The Neethling strain of the virus was initially weakened by 20 passes on the chorio-allantoic membranes of hen eggs in South Africa. The vaccine virus is now being grown in cell culture. It has been demonstrated that the vaccine made from sheep- or goatpox viruses gives cow immunity in Kenya. But for cattle, the amount of attenuation needed for safe usage in sheep and goats is insufficient.

Since live vaccinations could serve as a source of infection for susceptible sheep and goat populations, sheeppox and goatpox vaccines are only permitted in nations where the diseases are already widespread.

 

Adult vulnerable cattle should receive an annual LSDV vaccination to ensure optimal protection. At the site of the inoculation, about 50% of cattle have swelling (10-20 millimetres (12-34 mm) in diameter). Within a couple of weeks, this swelling goes down. Dairy cows that have been immunised could also experience a brief drop in milk production.