# TUBA KARA : Rhabdoviruses at “Virology by P. Saravanan (2017).” ::: info Rhabdoviruses are a (-) RNA virus family member and there are two different species that infect animals (Lysavirus and vesiculovirus). The type strain of Lyssa virus is Rabies and Vesiculovirus is VSV (vesicular stomatitis virus). ::: --- ![](https://i.imgur.com/sl9noJK.jpg) *SOURCE: WIKIPEDIA* Rhabdoviridae - Wikipedia. (2012). Retrieved 2 June 2021, from https://en.wikipedia.org/wiki/Rhabdoviridae --- **RABIES** --- ![](https://i.imgur.com/VP8esIz.jpg) SOURCE : How Dangerous Is Rabies Today?. (2021). Retrieved 3 June 2021, from https://www.verywellhealth.com/rabies-overview-4156466 --- Characteristics The rabies virus is an RNA virus member of the Rhabdoviridae (Greek, rhabdos = a stick), characteristically showing a bullet figure. Rabies and other viruses of the genus Lyssavirus (Greek, lyssa = madness) can infect vertebrates. Rabies is enzootic and sometimes epizootic in various mammalian species, including wild and domestic canids (e.g. dogs, foxes and coyotes), mustelids (skunks, badgers), creatures (mongoose, civets), procyonids (raccoons), and insectivorous and bloodsucking bats. ![](https://i.imgur.com/B6PXiYX.png) --- The Capsid Bullet-shaped lipoprotein envelope, with an average length of 180 nm and a diameter of 75 nm, consists of a helical nucleocapsid with virion 30-35 helixes. The ~200 glycoprotein (G) spikes of the virus, protruding from the lipid envelope surface, form another 10 nm from the envelope, covering the entire coating except for the blunt end of the envelope responsible for viral binding to cellular receptors. The M or Matrix protein is the main structural protein of the virus, located internally under the lipid membrane that surrounds the genome (figure 4.32). The genome consists of 11,932 nt RNA segments, 4.6 MDa (-). The 3' or RNA has 5 genes as M N, NS (or M1), M (2), G and L (Table 4.22) ![](https://i.imgur.com/Xk0h5al.png) --- **Replication strategy** The nicotine acetylcholine receptor is one of the junction sites for the virus, where the virus is internalized through receptor-mediated endocytosis. After fusion with the lysosome, nucleocapsid release occurs in the cytosol. The genome is transcribed into 5´ mRNA to produce viral protein. It then creates a full-length (+) strand as the template for the progeny viral genome. The viral envelope form is given from the host cistern membrane where the G and M proteins are placed (Figure 4.33). ![](https://i.imgur.com/SSLvQdR.png) **FIGURE 4.33** Steps in rhabdovirus infection: (1) virus attachment to phosphatidyl serine receptor (2) virus penetrates the cell in an endosome (3) virus fuses with endosomal membrane and core enters the cytoplasm (4) uncoating of nucleocapsid occurs (5) viral negative-sense RNA is transcribed into positive-sense RNA (6) positive-sense RNA serves as a template for synthesis of the viral genome as well as the mRNA that gives rise to viral proteins. This type of replicative process occurs with many viruses that form positive-sense RNA molecules (7) the negative-sense RNA becomes incorporated into nucleocapsids (N) (8) these NC subsequently join the matrix protein (M) at the basal surface of the cell (9) budding of virus from the cell surface takes place. --- **PATHOGENESIS** * Centripetal spread of the virus through peripheral nerves (retrograde axoplasmic flow). * It reaches the central nervous system. * Centrifugal propagation to many different tissues through peripheral nerves. Novation Novation after a break in the skin, replication occurs in the muscle cells, penetrating the muscle spindle, infecting the nerves innervating the spindle, moving centrally along the axons of these nerves, and increasing in the peripheral nerves. They occur in the dorsal ganglion at 60-72 hours and are carried through the sensory nerves. A natural rabies infection requires a period of local viral replication before the CNS infection occurs. Anti-rabies IgG administration and active immunization during this period can stop the spread of the virus to CNS. Adelchi Negri first identified cytoplasmic inclusions of rabies infection, which bore the name' Negri Bodies'. Human rabies the viral inoculum that accumulates during a bite and the location of the bite have a significant effect on the likelihood of developing rabies (table 4.23). --- ![](https://i.imgur.com/JSP1hFZ.jpg) SOURCE : Basicmedical Key 17 Rabies. (2017). Retrieved 3 June 2021, from https://basicmedicalkey.com/17-rabies/ --- ![](https://i.imgur.com/yPIgwbM.png) --- ![](https://i.imgur.com/PFvMcwz.png) * Duration of different stages of rabies * the first 90 days are very important for the incubation period of rabies (>75% cases). * Prodrome and carly symptoms: these symptoms cause fever, headache, weakness, nausea, vomiting, paresthesia, or pain in the wound area during the first 2-10 days of the disease. Acute neurological disease: human rabies infections are typically divided into two forms: angry and paralyzed (or mute). Furious rabies (80% cases) is manifested by hydrophobia, delirium and agitation within 2-7 days, others include hallucination, bizarre behavior, agitation, anxiety, biting, seizures, acrophobia, autonomic dysfunction and antidiuretic hormone syndrome (SIADH). * Paralyzed" stupid " rabies patients lack hydrophobia, acrophobia and seizures. Their initial findings may suggest an elevated paralysis or symmetrical quadriparesis, similar to acute inflammatory polyneuropathy (Guillain-Barre syndrome). Meningeal symptoms (headache, neck retention) may be pronounced. The disease progresses to a coma. --- **Growth characteristics** A newly isolated virus from natural human or animal infection is called Street virus. After a long and differing incubation period of 1-12 weeks, lethal encephalitis occurs in laboratory animals vaccinated by any method. Negri bodies can be exemplified in the brains of animals that have lost their lives due to street virus infection. ![](https://i.imgur.com/tDV2beJ.png) --- :::info Diagnosis In Animals A diagnosis can be made after determining the rabies virus from any part of the brain affected by the rabies virus, but in order to ignore rabies, the test must include tissue from at least two regions of the brain, preferably in two different regions, such as the brainstem and cerebellum. Before these tests can be performed, the animal needs to be euthanized.The Test takes about 2 hours, but it takes time to take brain samples from an animal suspected of having rabies and send these samples to a state public health or Veterinary Diagnostic Laboratory for diagnosis. ::: :::info Diagnosis in humans A variety of different tests are needed to diagnose rabies ante-mortem (before death) in humans ; a single test will not be sufficient for accurate analysis. Tests are performed along with saliva, serum, spinal fluid and skin biopsy samples of hair follicles taken from the nape region . After saliva, virus isolation or reverse transcription application processes are performed, then the test can be performed with polymerase chain reaction (RT-PCR). Serum and spinal fluid are checked to see if they have the necessary antibodies to the rabies virus. Skin biopsy samples are investigated for rabies antigen in the cutaneous nerves at the base of the hair follicles. ::: SOURCE: CDC - Diagnosis: In Animals and Humans - Rabies. (2021). Retrieved 3 June 2021, from https://www.cdc.gov/rabies/diagnosis/animals-humans.html#:~:text=Tests%20are%20performed%20on%20samples,for%20antibodies%20to%20rabies%20virus. --- Treatment and Prevention after exposure to rabies virus :::warning If an animal with rabies is exposed to a bite, it should be sterilized with plenty of water to minimize the excess virus in that area. ::: :::warning Human rabies immunoglobulin 20 Iu kg body weight to be administered intramuscularly in the gluteal region and second part to be infiltrated around bite. This is required in case of bite near head region. ::: :::warning Adequate tetanus prophylaxis is provided in the deltoid region 0,3,7,14,30 and 90. rabies vaccination should be applied on days. ::: --- ![](https://i.imgur.com/noEiXEQ.png) SOURCE : Can rabies be eliminated?. (2021). Retrieved 3 June 2021, from https://rabiesalliance.org/about/about-rabies/can-rabies-be-eliminated --- --- **Rabies vaccines** The rabies vaccine discovered by Pasteur contains the grounded spinal cord of a rabies-infected rabbit. Drying was performed among many methods to neutralize viursu. This virus is then designed with inactivation procedures such as rabies infected rabbit, sheep or goat brain which is subjected to virus inactivation with phenol (Fermi vaccine) at 22°C and 37°C (sample vaccine) or beta-propiolactone (BPL vaccines). --- **Non-neural vaccines** The duck egg vaccine was used for treatment for many years, which was discovered from virus growth in duck embryos and inactivated with BPL. Five to six doses of this vaccine are 0, 3, 7, 14, 30 and 90 after exposure in the deltoid region. it is considered appropriate to be shot on days. In order to reduce its commercial price, chick embryo cell vaccine and Vero cell rabies vaccine were developed in purified form.