Microbiology 3 group 2 Question 4-1-1.pptx

Microbiology presenation on viral infections

1. GROUP 2 SSALI EDWARD VU-BPC-2209-0152-DAY SSEKABIRA AARON AGUSTIN. VU-BPC-2301-0122-DAY SSANYU VIOLET. VU-BPC-2301- 0074-DAY SSEREMBA JOHN. VU-BPC-2301-0066-DAY TAHAKANISIBWA ANANIA. VU-BPC-2209-1471-DAY

2. QN. What are the structural characteristics of molluscum contagiosum virus, and how does it infect skin cells? Classification: MCV is a member of the Poxviridae family, specifically classified under the genus  Molluscipoxvirus . Structural Characteristics Shape and Size : MCV is typically oval-shaped, with dimensions of approximately 320 nm × 250 nm × 200 nm. Virion Structure: Nucleocapsid : The core contains the viral DNA. Core envelope: Surrounds the nucleocapsid . Lateral Bodies: Present between the core envelope and the outer membrane, containing proteins essential for viral replication.

3. Infectious Particles: MCV produces two distinct infectious particles: Mature Virion (MV): Lacks an outer membrane; enters host cells through fusion with the plasma membrane. Extracellular Virion (EV): Contains an additional outer cellular membrane, facilitating transmission.

4. Infection Mechanism : Entry into host c ells: MCV infects skin cells (keratinocytes) primarily through direct contact. The virion binds to glycosaminoglycans on the host cell surface, leading to entry via macropinocytosis . Replication : Once inside, MCV replicates in the cytoplasm, which is a unique feature among DNA viruses, as most replicate in the nucleus. This replication occurs in specialized areas called "viral factories."

5. QN. Explain the routes of transmission for MCV and why it commonly affects children. Molluscum contagiosum virus (MCV) is primarily transmitted through direct skin-to-skin contact, making it particularly common among children. Routes of Transmission. Direct Skin Contact : Touching the molluscum bumps on someone's skin. Engaging in close play, which is common among children. Indirect Transmission : The virus can also be transmitted via contaminated objects, such as: Towels Clothing Toys Shared athletic equipment

6. Environmental f actors: Warm and humid environments, such as swimming pools or communal showers, can facilitate the spread of MCV. Why MCV c ommonly affects c hildren Age g roup : MCV is most prevalent in children aged 1 to 10 years. The incidence peaks in preschool-aged children due to their high levels of skin-to-skin contact during play. Immune system : Young children often have immature immune systems that may not effectively combat the virus, making them more susceptible to infection. Behavioral f actors: Children are more likely to engage in activities that involve close physical contact and sharing personal items, increasing their risk of transmission.

7. QN. Describe the clinical features of molluscum contagiosum and the diagnostic methods used. Molluscum contagiosum is a benign viral infection characterized by distinctive skin lesions. It primarily affects children but can also occur in adults, especially those with weakened immune systems. Clinical Features Lesion Characteristics : Appearance: Small, firm, rounded papules that are typically 2 to 5 mm in diameter. Color : Lesions may be pink, flesh-colored, or white. Surface : Shiny and umbilicated surface. Distribution : Commonly appears on the trunk, extremities, face, and genitals; rarely on palms and soles.

8. Other symptoms : Lesions are usually painless but can become itchy or inflamed. In some cases, erythema and swelling may occur as the immune response begins to clear the infection. Duration: The lesions are self-limiting and typically resolve within 6 to 12 months, but may persist for longer in some individuals. Special c ases: In immunocompromised patients, lesions may be more numerous, larger (giant molluscum ), and located in atypical areas such as the scalp or mucosal surfaces.

9. Diagnostic Methods Clinical diagnosis: Diagnosis is primarily clinical based on the characteristic appearance of lesions. Dermoscopy : D ermatoscopic examination reveals specific features such as white-to-yellow polylobular structures and crown vessels. Histological examination: If the diagnosis is uncertain, a biopsy may be performed to identify large intracytoplasmic eosinophilic inclusion bodies known as Henderson- Petterson bodies. Differential d iagnosis: Important to differentiate from other skin conditions such as warts, folliculitis, or other viral infections.

10. What are the current treatment and prevention strategies for molluscum contagiosum ? 1. Self-limiting n ature :Molluscum contagiosum typically resolves on its own within 6 to 12 months, making treatment often unnecessary for healthy individuals. 2. Topical treatments : VP-102 ( Cantharidin ): A proprietary formulation that has shown promise in clinical trials, resulting in significant clearance of lesions. SB206 ( Berdazimer Sodium): A nitric oxide-releasing gel that has demonstrated effectiveness in reducing lesions. Other t opicals : Podophyllotoxin cream (0.5%) Salicylic acid Tretinoin Iodine preparations

11. 3. Physical Removal Methods: Cryotherapy: Freezing the lesions with liquid nitrogen; effective but can cause discomfort and potential scarring. Curettage: Surgical scraping of lesions; offers high clearance rates but may require local anesthesia and can result in scarring. Laser Therapy: Utilizes focused light to destroy lesions; effective but typically reserved for extensive cases. 4. Immunomodulatory Treatments : Cimetidine, an oral medication, may help stimulate the immune response, particularly in pediatric patients.

12. Prevention Strategies Hygiene Practices: Regular hand washing with soap and water to reduce transmission risk. Avoid sharing personal items like towels, clothing, or sports equipment. Covering lesions: Covering bumps with waterproof bandages during swimming or contact sports to minimize spread. Environmental p recautions: Disinfecting surfaces in communal areas (e.g., gyms, pools) to reduce virus survival and spread. Education and a wareness: Informing caregivers and children about the transmission routes and how to avoid spreading the virus. Avoiding skin-to-skin c ontact: Limiting close contact with infected individuals until lesions have resolved.

13. QUESTION FOUR

14. •What are the structural characteristics of the canarypox virus, and how does it differ from other Poxviridae members? Structural Characteristics of Canarypox Virus Structure: The canarypox virus is an enveloped virus with a linear double-stranded DNA genome, similar to other members of the Poxviridae family, but it is smaller, typically around 200-300 nm in size. Differences: Unlike variola or vaccinia viruses, canarypox does not replicate in mammalian cells and is less pathogenic to humans, making it a safer vaccine vector.

15. • How is the canarypox virus used as a vector in vaccines, and what makes it effective in this role? Use of Canarypox as a Vaccine Vector Vector Role: CNPV is utilized as a vaccine vector due to its ability to express foreign antigens without replicating in human cells, making it a safer option than traditional poxvirus vectors like vaccinia . Canarypox is engineered to carry genes from other pathogens, allowing it to express foreign antigens without causing disease. Effectiveness: Its non-replicative nature minimizes the risk of disease while still inducing a robust immune response, which is advantageous for vaccine development against various pathogens .

16. • Discuss how canarypox -based vaccines stimulate the immune response in humans. Immune Activation: Canarypox -based vaccines stimulate both humoral (antibody-mediated) and cellular (T-cell mediated) immune responses. Mechanism: The expressed antigens are presented via MHC class I and II pathways, activating CD8+ cytotoxic T cells and CD4+ helper T cells, leading to enhanced immune protection. 

17. What are the advantages and limitations of using canarypox as a vaccine vector? Advantages: High safety profile due to non-replicative nature. Induces strong immune responses without the risk of disease. Versatile for use against multiple pathogens . Limitations: Pre-existing immunity in some populations may reduce effectiveness. Limited capacity for large antigen payloads compared to other viral vectors .