Canine distemper infects brain tissues of the dogs

Monika Raman, PSG College of Technology, Coimbatore

Canine distemper (CD) is by the Morbillivirus genus of the Paramyxoviridae family’s canine distemper virus (CDV). It is still a global epidemic of infectious diseases, particularly in domestic dogs in China, causing substantial harm to the growth of the dog industry. 

According to recent studies, the possibility of canine distemper re-emergence exists, and some new strains of CDV are detected in Asia. It appears to indicate that we must prioritize CD prevention and control at this time. 

Demyelinating pathogenesis – Characteristic of CDV-infected dogs 

CD is due to immunosuppression and impacts the central nervous system (CNS). The CNS damage seen in CDV-infected dogs is a prominent feature. In the acute stages of CD – demyelinating encephalopathy is the most frequent histological pathology.

Pathologically, CNS changes involve demyelination in the nerve fibre bundle and heterogeneous neuron degeneration. It occurs in both white matter and grey matter. Demyelination and increased viral replication in white matter-glial cells occur before glial cell infection. 

Apathy, stupor, behaviour problem, seizures, ataxia, tetraplegia, incontinence – are the most prevalent clinical symptoms in dogs with CD. Although dogs with CD typically exhibit several neurological symptoms, it is difficult to diagnose them in clinics based on neurological indications. 

According to prior research, CDV causes apoptosis in vivo (cerebellum and lymphoid tissue) of CD-infected dogs. CDV also induces apoptosis in Vero and HeLa cells in vitro. Its presence in brain tissue cells, however, is unknown. 

So, a team of researchers from Xinxiang, China – aimed to see if CDV caused apoptosis in the brains of naturally infected dogs. They also discovered a link between CDV infection and demyelinating pathology in the brain via apoptosis.

Do CDV induce apoptosis in brain tissue?

Apoptosis in brain tissues was studied – to determine the link between canine distemper infecting brain tissues.

They discovered that CDV could infect the endothelium of the brain vessel and the astrocytic feeding process that surrounds the blood arteries as a result of their investigation. A severe infection leads to apoptosis – which can break the blood-brain barrier and allow viruses to enter the grey and white matter. 

CDV invades ependymal cells, causes apoptosis, disrupts the cerebroventricular barrier, and infiltrates the white matter. CDV that has infected brain tissues infects glial cells, a neuron in the nerve nucleus, pyramidal cells, and Purkinje cells and triggers apoptosis in some infecting cells.

As a result, they established that apoptosis in brain cells was primarily linked to CDV transmission and cytotropism. They also claimed that several neurological symptoms seen in the clinic might be linked to distinct types of neuron death.

Relationship between demyelinating pathogenesis and apoptosis in brain tissues

Some studies have looked into the underlying mechanism of demyelination in CD dogs. They discovered that astrocytes and oligodendrocytes play a role in nerve fibre demyelination.

Apoptosis of neurons and glial cells is linked to demyelination in brain tissues, according to this study. This study proves that apoptosis of astrocytes, oligodendrocytes – plays a major role in demyelinating pathogenesis.

To prevent CD

“To our knowledge, this is the first study to demonstrate that spontaneous CDV infection causes apoptosis in all types of brain tissue cells,” says Yaoqian Pan, the primary author of the study.

Unfortunately, there is no easy or accurate way to diagnose distemper in all affected dogs. Effective vaccination, quarantine, isolation, illness recognition/diagnostic testing, and environmental cleanup are required to control distemper. As a result, gaining a better knowledge of the disease’s natural history, as done in this study, may aid in the development of an effective prevention strategy. 

Also read: Chagas disease spread by kissing bugs: Rise of cardiac issues

Reference: Pan, Y., Wang, S., Li, P., Yue, F., Zhang, Y., Pan, B., & Liu, X. (2021). Apoptotic investigation of brain tissue cells in dogs naturally infected by canine distemper virus. Virology Journal, 18(1), 165. https://doi.org/10.1186/s12985-021-01635-8

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About the author: Monika Raman is an undergraduate student pursuing her final year B. Tech in Biotechnology. She is an enthusiastic Biotech student aspiring for an opportunity to develop skills and grow professionally in the research field. Extremely motivated and possess strong interpersonal skills.