SURVEY OF RNA AND DNA CONTAINING VIRUSES.pptx

DNA AND RNA VIRUSES

1. TOPIC: i. Survey Of RNA-containing Viruses ; Picornavirus Astrovirus i i. Survey Of DNA-containing Viruses; Circovirus

2. RNA-CONTAINING VIRUSES I.PICONAVIRUS They are small single stranded icosahedral non-enveloped RNA viruses measuring 28-30 nm. Their capsid encases a positive sense RNA strand consisting of approximately 7500 nucleotides. The RNA carries a covalently bound non capsid viral protein (VPg) containing 60 protein subunits each consisting of four polypeptides: VP1, VP2, VP3, and VP4. They replicate in the cytoplasm. Because they contain no essential lipids, they are ether resistant.

3. Picornaviruses affecting human are: a. Enteroviruses (gut infections) comprises of four viruses: ● Poliovirus, 1, 2, 3 which causes Poliomyelitis encephalitis. Transmission route is through Faecal - oral ● Coxsackie A ( 1–24) and Coxsackie B ( 1–6) viruses which causes respiratory infection rash , meningo-encephalitis and myocarditis. T ransmission is f aecal-oral and respiratory droplets ● Echoviruses 1–34 , has same infections and transmission as Coxsackie. ● Enteroviruses 68–71 causes respiratory disease and haemorrhagic conjunctivitis. Transmission is through r espiratory droplets. b. Rhinoviruses (upper respiratory infections). It is the major cause of colds. Transmission is by respiratory droplets. c. Hepatoviruses (Hepatitis A) affect the intestines and liver causing gastroenteritis and Hepatitis A. Their mode of transmission is fecal oral route. Picornaviruses infecting animals include foot-and-mouth disease of cattle and encephalomyocarditis of rodents.

4. Lab Diagnosis Specimen used include: throat swab, nasopharygeal swab, blood, stool and CSF. Methods used include: Molecular testing fluid e.g RT-PCR, Serological tests e.g ELISA, neutralization assays Culture in cell lines e.g rabdomyosarcoma (RD) Next-generation sequencing. Electron microscopy

5. Treatment I. Symptomatic treatment. Involves medications to relief fever, pain etc. Fluid intake to prevent dehydration and loosen respiratory secretions. II. Respiratory support nasal. To relief nasal congestion and sinus pressure Cough supplements to reduce cough frequency. Inhalation therapy eg steam inhalation to humidify or soothe irritated airways. Nasal cannula Non re-breather mask Face-mask

6. Prevention Practicing good personal hygiene and covering the mouth when sneezing or coughing, avoid sharing personal items. vaccination; Poliomyelitis can be prevented by Salk-type (inactivated) via injection and Sabin-type (live-attenuated) vaccination orally. Hepatitis A virus vaccine (killed/inactivated) during infancy or for travelers travelling to endemic areas.

7. II.ASTROVIRUS These viruses belong to family Astriviridae. T hey consists of two genera; Mamastrovirus which affects mammals and Avastrovirus affecting birds. They are non-enveloped with single-stranded, positive-sense RNA genomes measuring 28-35 nm icosahedral virus with 5-6 pointed star-like structure. Astrovirus is the common cause of gastroenteritis . Commonly referred as stomach bug or stomach flu. Mostly affect children, adults above 65 years and immunocompromised individuals.

8. Astrovirus infection can be asymptomatic. Common clinical symptoms include: Mild waterly diarrhea Nausea Vomitting Abdominal pain Fever Complicated cases can cause encephalitis and meningitis. Transmission is through fecal- oral route by contaminated water, food and items or surfaces. Astrovirus is contagious.

9. Laboratory diagnosis is done from stool specimen using: PCR to detect genetic material of the virus. EIA to detect the presence of antigen in stool . Electron microscopy Cell culture immunoassays

10. Control and prevention is through: Frequent hand-washing. Washing vegetables and fruits with clean water. Avoid swallowing water when swimming in public pools. Proper human waste disposal Drinking clean or treated water . No vaccine for Astrovirus.

11. D NA CONTAINING VIRUS CIRCOVIRUS Circoviridae family comprises of two genera: circovirus ( birds/pigs ) with 39 species and cyclovirus ( birds ) with 48 species . Circoviruses are icosahedral, non-enveloped viruses with circular, single-stranded DNA genomes. The capsid is composed of a single viral protein which encloses a genome typically ranging from 1.7-2.2 kb in length. This genome harbors two major open reading frames (ORFs) coding for the viral replication-associated protein (Rep) and the capsid protein. Due to this limited genome coding, they rely highly on the host. Circovirus is transmitted through fecal-oral and parenteral routes.

12. Diseases associated include: Post-weaning multisystem wasting syndrome (PCV-2 ). Porcine Respiratory Disease Complex (PRDC ). Porcine Dermatitis and Nephropathy Syndrome (PDNS) Avian Circovirus Disease (ACVD ).

13. Additional topic Human circovirus I (HCirV-1) Human Circovirus 1 is a novel virus distant from known animal circoviruses. It was first discovered in a French hepatitis case involving a patient undergoing immunosuppressive treatment. T wo more cases of Chinese drug users were diagonised. (HCirV-1 and HCirV-2). Both cases implicated damage to the liver damage and have been published in the journal  Emerging Infectious Diseases  on January 3, 2023. Mechanisms of replication concerning human circoviruses are still unknown. They are highly resistant DNA viruses which can cause respiratory, renal, dermatological and reproductive problems.

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