Геномы мен құрылымы
сфера формалы, диаметрі 25-30 нм бір тізбекті сегменттелмеген +РНК вирус
АГВ
A pregnant woman at 28 weeks presented with fever, runny nose, sore throat, eye redness, and weakness. Later, conjunctivitis and diarrhea developed. Inflammatory changes of the respiratory and intestinal mucosa were detected, and short-term viremia was confirmed. The pathogen affects vascular endothelium, causing exudative inflammation with the formation of fibrinous membranes and necrosis. There is a risk of transplacental infection of the fetus.
What complications may develop in the fetus during transplacental transmission of the infection?
Adenoviruses: Transplacental transmission of the infection can lead to several serious fetal complications:
A 35-year-old woman recovered from influenza A infection two months ago. She now presents with sudden fever, chills, headache, muscle aches, and cough—classic symptoms of the flu. She asks the doctor: “I just had the flu recently—why am I sick again?”
Question:
Why doesn’t the immune system prevent influenza from developing upon reinfection?
The immune system often cannot fully prevent reinfection with influenza due to antigenic variation of the virus:
Which type of virological test is used to detect influenza viruses?
virological methods using embryonated chicken eggs or cell cultures
Why isn’t the immune system fully protective during a second influenza infection?
Because influenza viruses mutate frequently, so previous immunity may not recognize the new strain
Диаметрі 55-65 нм сфера формалы, біртізбекті сегменттелмеген +РНК вирус
СГВ
45-year-old patient was diagnosed with influenza 3 days ago, presenting with fever, chills, headache, and dry cough. Initially, symptoms were typical of influenza, but on the fourth day, the patient developed worsening cough with purulent sputum, chest pain, and shortness of breath.
Examination reveals signs of bacterial pneumonia. Laboratory tests show elevated white blood cells and inflammatory markers.
Question:
How does influenza infection predispose the patient to secondary bacterial infections, and which bacteria are most commonly involved?
Influenza infection damages the respiratory tract by causing cellular destruction and desquamation of the superficial mucosa, which weakens the natural barrier against pathogens. This makes the respiratory tract highly susceptible to secondary bacterial infections:
A 25-year-old man was bitten by a stray dog. He did not seek medical attention immediately. One week later, he develops fever, malaise, and neurological symptoms. His family asks why treatment wasn’t effective when given at this stage.
Question:
Why isn’t the treatment effective one week after a dog bite?
After a dog bite, certain viruses (e.g., rabies virus) initially replicate in the muscle at the bite site and then travel along peripheral nerves toward the central nervous system (CNS).
Why is laboratory testing not usually performed for mumps?
because the clinical presentation of the disease is very characteristic: typical swelling of the parotid glands (on one or both sides), fever, and pain when chewing
How is coronavirus infection controlled given the lack of specific therapy and high mutation rate?
By strict isolation and quarantine
Диаметрі 42-47 нм, суперкапсиді бар, Сақиналы екі жіпшелі, ДНҚлы вирус
ВГВ
A 10-year-old child presents with fever, malaise, and headache for 2 days. The parents notice swelling and tenderness in front of the ears, and the child complains of pain while chewing.
Laboratory tests confirm viral infection. The history reveals recent contact with a classmate who had similar symptoms.
Question:
How does the virus spread in the body to cause parotid gland swelling, and which cells serve as the primary sites of viral replication?
The mumps virus is spread by the viremia throughout the body to the testes, ovary, pancreas, thyroid, and other organs. Primary replication occurs in nasal or upper respiratory tract epithelial cells.
A 4-year-old child presents with fever, runny nose, cough, and red eyes. Two days later, a red, blotchy rash appears on the face and gradually spreads to the trunk and legs. The parents ask why the rash starts on the head and moves downward.
Question:
Why does the measles rash begin on the head and spread down to the feet?
The measles rash is caused by immune-mediated responses to viral infection of endothelial cells in small blood vessels.
What methods are used to detect the measles virus in modern laboratory testing?
ELISA and PCR
Why are measles and mumps most common in children?
Because children have not yet developed immunity from previous infection or vaccination
The virion consists of a helical nucleocapsid contained in a bullet-shaped lipoprotein envelope 180 × 75 nm, the genome is single-stranded RNA, linear, non- segmented, negative-sense.
The rabies virus
A 6-year-old child was exposed to a classmate with measles 10 days ago. The child now presents with fever, runny nose, cough, and red eyes. Two days after the onset of fever, small bluish-white spots appear on the buccal mucosa opposite the molars.
Question:
What is the significance of the buccal mucosa lesions, and how do they help in diagnosing the disease?
The small bluish-white spots on the buccal mucosa, known as Koplik’s spots, are pathognomonic for measles. Their appearance confirms the diagnosis with certainty, even before the characteristic skin rash develops.
A 12-year-old boy presents with fever, malaise, and painful swelling in front of his ears. His parents are concerned and ask why only the parotid glands are affected, while other salivary glands seem normal.
Question:
Why is it that only the parotid gland is typically affected in mumps?
Mumps virus has a tropism for epithelial cells of the parotid gland due to:
What is observed on histological examination of cerebellar cortex cells following Romanovsky–Giemsa staining in cases of rabies?
Negri bodies are observed
What is the specific preventive treatment for measles and mumps?
The MMR (measles, mumps, and rubella) vaccine schedule is:
Virus are 70–90 nm in diameter and display icosahedral symmetry. There is no envelope. The capsid is composed of 252 capsomers, the DNA is linear and double stranded.
Adenoviruses
A 28-year-old man was bitten by a wild animal suspected of carrying a virus. He develops symptoms—fever, malaise, and neurological signs—within 10 days. In contrast, another patient who had a similar exposure several months ago only develops symptoms after 6 months.
Question:
Why do symptoms appear quickly in some people but take months or years in others after exposure to the same virus?
The variation in incubation period depends on several factors:
In a virology lab, a student, Alex, is testing how different viruses survive on surfaces. He puts two samples on a table: influenza virus and adenovirus. After spraying both surfaces with alcohol, he observes that the influenza virus is quickly inactivated, but the adenovirus remains active.
Alex asks his lab partner: "Why does the adenovirus survive while the influenza virus doesn’t?"
The adenovirus is resistant because it has a non-lipid capsid made of proteins instead of a lipid envelope. Lipid envelopes, like those in influenza or HIV, are easily destroyed by alcohol or detergents. Additionally, the capsid proteins (hexon, penton, fiber) of the adenovirus are tightly bound, making it stable against changes in temperature, pH, and ions. This combination allows adenovirus virions to remain active in conditions that inactivate enveloped viruses.
Which biological method is used to culture adenoviruses?
The clinical specimens are inoculated in tissue culture such as HeLa, Hep.
Can a person with clinical rabies symptoms 7 weeks after exposure still be vaccinated?
No. Once clinical symptoms of rabies appear, vaccination is no longer effective. At this stage, rabies is almost always fatal-died.