Lecture 8: Medical Virology PDF

28 March 2023 LECTURE 8 By ABDULFATAH MOHAMMED AL-BAKKOSH 1 1444 ،‫ رمضان‬08 ADENOVIRUS MORPHOLOGY • Icosahedral, about 80- 110 nm diameter • Genome is dsDNA • Replicates in nucleus PATHOGENESIS • they can cause illness of respiratory system gastroenteritis, conjunctivitis and cystitis . • Aden...

28 March 2023 LECTURE 8 By ABDULFATAH MOHAMMED AL-BAKKOSH 1 1444 ،‫ رمضان‬08 ADENOVIRUS MORPHOLOGY • Icosahedral, about 80- 110 nm diameter • Genome is dsDNA • Replicates in nucleus PATHOGENESIS • they can cause illness of respiratory system gastroenteritis, conjunctivitis and cystitis . • Adenoviruses are transmitted mainly by respiratory or feco-oral contact from humans. 2 1444 ،‫ رمضان‬08 28 March 2023 LECTURE 8 ADENOVIRUS LABORATORY DIAGNOSIS Specimens : from throat, eye, urine, feces; Isolation of virus: – Inoculation into cell cultures; – human embryonic kidney/HeLa Detection of antigen , PCR Control: • vaccine (live). 3 1444 ،‫ رمضان‬08 polymerase chain reaction a technique that amplifies a specific segment of DNA or RNA from a sample. PCR is widely used in molecular biology, biotechnology, medicine and forensics. PCR can detect the presence of pathogens, identify genetic variations, clone DNA fragments 4 1444 ،‫ رمضان‬08 28 March 2023 LECTURE 8 polymerase chain reaction The procedure involves the following steps: - Denaturation: The DNA sample is heated to separate the two strands of the double helix. - Annealing: The temperature is lowered and primers (short sequences of DNA that match the target segment) bind to the complementary regions on the DNA strands. - Extension: The temperature is raised again and a DNA polymerase enzyme adds nucleotides to the primers, extending them and creating new copies of the target segment. These steps are repeated multiple times, doubling the amount of target DNA in each cycle. 5 1444 ،‫ رمضان‬08 6 1444 ،‫ رمضان‬08 28 March 2023 LECTURE 8 7 1444 ،‫ رمضان‬08 Measles virus Rubella virus is a single-stranded, negative-sense, enveloped RNA virus. Measles, or rubella, is a viral infection of the respiratory system. 8 1444 ،‫ رمضان‬08 28 March 2023 LECTURE 8 Measles virus TRANSMISSION • Measles is an airborne disease which spreads easily through the coughs and sneezes of infected people. It may also be spread through direct contact with mouth or nasal secretions. 9 1444 ،‫ رمضان‬08 Measles virus • Measles is a viral infection that causes fever, cough, cold, red eyes, and rashes. • It can also lead to serious complications such as ear infections, bronchitis, miscarriage, low blood platelets, blindness, and severe diarrhea. • The infection can be diagnosed by the presence of white spots inside the mouth called Koplik's spot 10 1444 ،‫ رمضان‬08 28 March 2023 LECTURE 8 Measles virus • LABORATORY DIAGNOSIS Detection of nucleic acid ( PCR ) and detection of antigen . • PREVENTION • Mothers who are immune to measles pass antibodies to their children, which can give newborn infants some immunity. However, these antibodies gradually lose over the first nine months of life, making infants under one year of age susceptible to infection with the measles virus. • Vaccination 11 1444 ،‫ رمضان‬08 MUMPS • The mumps virus is a member of the Paramyxoviridae family of enveloped RNA viruses. • It has a single-stranded, negative-sense RNA genome that encodes nine proteins. • The virus structure consists of a helical nucleocapsid core surrounded by a lipid bilayer membrane. The membrane contains two glycoproteins: hemagglutinin-neuraminidase (HN) and fusion (F) protein. The HN protein binds to sialic acid receptors on host cells and facilitates virus attachment and entry. • The F protein mediates membrane fusion and viral penetration. 12 1444 ،‫ رمضان‬08 28 March 2023 LECTURE 8 MUMPS • Mumps is a viral disease caused by the mumps virus. TRANSMISSION • The virus is transmitted by respiratory droplets or direct contact with an infected person. SYMPTOMS • Initial signs and symptoms often include fever, muscle pain, headache and feeling generally unwell This is then usually followed by painful swelling of one or both parotid salivary glands. 13 1444 ،‫ رمضان‬08 MUMPS • Complications • Painful testicular inflammation, Ovarian inflammation, Acute pancreatic inflammation, Brain inflammation. • DIAGNOSIS • A physical examination confirms the presence of the swollen glands, PCR. • Control • Mumps is preventable by two doses of the mumps vaccine . 14 1444 ،‫ رمضان‬08 28 March 2023 LECTURE 8 Chickenpox • also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV) • Their structure is complex and conforms to neither icosahedral nor helical symmetry, genome is linear doublestranded DNA, enveloped 15 1444 ،‫ رمضان‬08 Chickenpox • Transmission • Chickenpox is an airborne disease which spreads easily through the coughs and sneezes of an infected person. It may be spread from one to two days before the rash appears until all lesions have crusted over. It may also spread through contact with the blisters. • Pathogenesis • The disease causes a skin rash that spreads to the rest of the body, with other symptoms such as fever, fatigue, and headaches. Symptoms begin 10-21 days after exposure. • Diagnosis by (PCR) testing of the blister fluid or scabs and serological tests. 16 1444 ،‫ رمضان‬08 28 March 2023 LECTURE 8 Smallpox • Poxviruses are a group of viruses that have a brickshaped morphology and a linear double-stranded DNA genome. They are enveloped viruses, meaning they have a lipid membrane surrounding their protein core. Poxviruses have a simple life cycle that involves replication in the cytoplasm of the host cell and release by budding or cell lysis. 17 1444 ،‫ رمضان‬08 Smallpox • Transmission Smallpox virus is transmitted via respiratory aerosol or by direct contact with virus either in the skin lesions . • Pathogenicity Smallpox begins when the virus infects the upper respiratory tract and local lymph nodes and then enters the blood (primary viremia). Internal organs are infected; then the virus reenters the blood (secondary viremia) and spreads to the skin. 18 1444 ،‫ رمضان‬08 28 March 2023 LECTURE 8 Smallpox • Symptoms: • Smallpox has an incubation period of 7-17 days and can cause fever, vomiting, sores in the mouth, and a skin rash. Over time, the skin rash turns into fluid filled bumps with a dent in the center, which then scabbed over and fell off leaving scars. It can spread between people or through contaminated objects. • Laboratory Diagnosis PCR and electron microscopy • Control : by vaccination 19 1444 ،‫ رمضان‬08 Smallpox 20 1444 ،‫ رمضان‬08