Lecture 15: Reovirus, (Toga,Flavi), (Bunya, Arena) - Chap 51, 52, 53

Question 1

What is the structure of the Reovirus genome?

Answer 1

Double-stranded RNA with 10-12 segments.

Question 2

Which capsid protein in rotaviruses is a target for neutralizing antibodies?

Answer 2

VP4 and VP7.

Question 3

How does rotavirus enter cells and initiate infection?

Answer 3

Through endocytosis or fusion after acid cleavage activates it in the stomach.

Question 4

What are common symptoms of rotavirus infection in infants?

Answer 4

Watery diarrhea, vomiting, and dehydration.

Question 5

What is the function of the NSP4 protein in rotavirus?

Answer 5

Acts like a toxin, causing electrolyte loss and fluid imbalance.

Question 6

How is Colorado Tick Fever Virus primarily transmitted?

Answer 6

By the wood tick, Dermacentor andersoni.

Question 7

Which diagnostic method can confirm a rotavirus infection?

Answer 7

ELISA on stool samples or RT-PCR.

Question 8

What is the genome structure of togaviruses and flaviviruses?

Answer 8

Single-stranded, positive-sense RNA.

Question 9

Where do togaviruses and flaviviruses replicate in host cells?

Answer 9

Togaviruses at the plasma membrane; flaviviruses at intracellular membranes.

Question 10

Which mosquitoes are main vectors for arboviruses?

Answer 10

Aedes and Culex mosquitoes.

Question 11

What is the role of the polyprotein in flavivirus replication?

Answer 11

It is cleaved into structural and non-structural proteins needed for viral assembly.

Question 12

What are common symptoms of Dengue Fever?

Answer 12

High fever, severe joint pain (‘breakbone fever’), and rash.

Question 13

What complication can arise from a second dengue infection?

Answer 13

Dengue Hemorrhagic Fever or Dengue Shock Syndrome.

Question 14

How is West Nile Virus typically transmitted?

Answer 14

By mosquitoes, primarily Culex species.

Question 15

What are common symptoms of West Nile Virus?

Answer 15

Flulike symptoms, sometimes progressing to encephalitis.

Question 16

How is Yellow Fever controlled in endemic regions?

Answer 16

Vaccination with the live-attenuated yellow fever vaccine.

Question 17

What is a significant birth defect risk associated with Zika virus?

Answer 17

Microcephaly in infants born to infected mothers.

Question 18

How is Zika virus primarily spread?

Answer 18

Aedes mosquito bites and sexual transmission.

Question 19

What unique feature do Bunyaviruses lack in their structure?

Answer 19

Matrix proteins.

Question 20

How is Hantavirus transmitted to humans?

Answer 20

Inhalation of aerosols from rodent urine or feces.

Question 21

What disease does Hantavirus cause in humans?

Answer 21

Hantavirus Cardiopulmonary Syndrome (HCPS).

Question 22

What is the genome structure of arenaviruses?

Answer 22

Ambisense, segmented single-stranded RNA.

Question 23

What is the primary vector for Lassa Fever?

Answer 23

Rodents, particularly Mastomys species.

Question 24

Which arenavirus can cause hemorrhagic fever?

Answer 24

Lassa virus.

Question 25

What are the main symptoms of Lassa Fever?

Answer 25

Fever, coagulopathy, hemorrhage, and shock.

Question 26

What is the primary means of preventing Lassa Fever?

Answer 26

Controlling rodent populations and avoiding exposure to their excretions.

Question 27

What virus is commonly found in blood cells and causes biphasic fever?

Answer 27

Colorado Tick Fever Virus.

Question 28

Which bunyavirus commonly affects people in forested areas?

Answer 28

California Encephalitis Virus.

Question 29

What does 'arbovirus' stand for?

Answer 29

Arthropod-borne virus.

Question 30

How does the immune response contribute to Dengue's severity?

Answer 30

Non-neutralizing antibodies can enhance infection in a second exposure.

Question 31

What type of genome does Reovirus have?

Answer 31

Double-stranded RNA (dsRNA)

Question 32

Describe the capsid structure of Reoviruses.

Answer 32

Double-layered capsid with icosahedral symmetry

Question 33

How are Reoviruses resistant to environmental factors?

Answer 33

Resistant to acidic pH, detergents, and drying

Question 34

Where does Reovirus replication take place in the host cell?

Answer 34

Cytoplasm

Question 35

Outline the major steps in the Rotavirus lifecycle.

Answer 35

1) Activated in stomach, 2) Forms ISVP in acidic environment, 3) Enters small intestine, 4) Replicates in enterocytes, 5) New virions released by cell lysis

Question 36

What protein in Rotavirus acts as a toxin, leading to diarrhea?

Answer 36

NSP4 protein

Question 37

How does Rotavirus infection typically spread?

Answer 37

Fecal-oral route, possible respiratory route

Question 38

What key symptoms characterize Rotavirus infection?

Answer 38

Watery diarrhea, vomiting, dehydration

Question 39

What is the main treatment for severe dehydration caused by Rotavirus?

Answer 39

Oral rehydration therapy

Question 40

Describe the genome of Togaviruses.

Answer 40

Single-stranded, positive-sense RNA

Question 41

What is the replication site for Togaviruses?

Answer 41

Cytoplasm

Question 42

How does Togavirus lifecycle proceed in early and late protein synthesis?

Answer 42

1) Early synthesis of nonstructural proteins, 2) Late synthesis of structural proteins

Question 43

Summarize the steps in Togavirus replication.

Answer 43

1) Entry via receptor-mediated endocytosis, 2) RNA released in cytoplasm, 3) Polyprotein cleaved into functional proteins, 4) Assembly at plasma membrane, 5) Budding and release

Question 44

How is Rubella, a Togavirus, different in transmission from other members?

Answer 44

Transmitted by respiratory route, not an arbovirus

Question 45

What are symptoms of Rubella infection?

Answer 45

Mild rash, fever, arthralgia; teratogenic effects in congenital infection

Question 46

Describe the structure of Flaviviruses.

Answer 46

Enveloped, single-stranded positive-sense RNA

Question 47

Where do Flaviviruses replicate within the host cell?

Answer 47

Cytoplasm

Question 48

Explain the Flavivirus replication cycle.

Answer 48

1) Entry via receptor-mediated endocytosis, 2) Genome translated into polyprotein, 3) Polyprotein cleaved into functional proteins, 4) Assembly in endoplasmic reticulum, 5) Budding at intracellular membranes, 6) Release by exocytosis

Question 49

How do Flaviviruses evade the immune system?

Answer 49

Use Fc receptors on monocytes/macrophages for entry

Question 50

What are the symptoms of Dengue fever?

Answer 50

High fever, retroorbital pain, rash, severe joint pain ('breakbone fever')

Question 51

How is Dengue transmitted?

Answer 51

By Aedes mosquitoes

Question 52

What severe condition can occur with a secondary Dengue infection?

Answer 52

Dengue hemorrhagic fever (DHF) and Dengue Shock Syndrome (DSS)

Question 53

Describe the unique feature of the Bunyavirus genome.

Answer 53

Three segmented RNA strands (L, M, S) with pseudo-circular shape

Question 54

What is the typical site of Bunyavirus replication?

Answer 54

Cytoplasm

Question 55

Outline the Bunyavirus replication cycle.

Answer 55

1) Enters via receptor-mediated endocytosis, 2) Genome segments transcribed in cytoplasm, 3) Transcripts used for protein synthesis, 4) Assembly at Golgi apparatus, 5) Released by budding

Question 56

How are California Encephalitis and La Crosse viruses (Bunyaviruses) transmitted?

Answer 56

By Aedes mosquitoes

Question 57

What are common symptoms of La Crosse encephalitis?

Answer 57

Headache, fever, nausea, stiff neck, encephalitis

Question 58

What is the structure and genome of Arenaviruses?

Answer 58

Enveloped, ambisense single-stranded RNA with two segments

Question 59

Describe Arenavirus ribosomes' unique role.

Answer 59

Host cell ribosomes are incorporated, giving virions a sandy appearance

Question 60

Explain the Arenavirus lifecycle.

Answer 60

1) Entry via endocytosis, 2) Ambisense RNA transcribed in cytoplasm, 3) Translation of proteins, 4) Assembly in cytoplasm, 5) Budding from plasma membrane

Question 61

What severe disease is caused by Lassa virus (Arenavirus)?

Answer 61

Lassa fever, characterized by fever, coagulopathy, visceral hemorrhage

Question 62

How are Lassa fever and other Arenaviruses primarily transmitted?

Answer 62

Via rodent urine/feces and aerosols from infected rodents

Question 63

What diagnostic test is used for Rotavirus detection in stool samples?

Answer 63

ELISA

Question 64

How is Colorado Tick Fever diagnosed?

Answer 64

Detection of virus in red blood cells (RBCs)

Question 65

How is La Crosse virus transmitted to humans?

Answer 65

Through the bite of Culex mosquitoes

Question 66

Describe the main mode of prevention for Dengue virus transmission.

Answer 66

Mosquito control, especially eliminating standing water

Question 67

What is the primary method for diagnosing Flavivirus infections like Dengue?

Answer 67

RT-PCR for viral RNA

Question 68

How can Rubella infection be confirmed, especially in pregnancy?

Answer 68

IgM antibody test

Question 69

What is the effect of congenital Rubella syndrome?

Answer 69

Birth defects, particularly with infection during the first trimester

Question 70

How do Arenaviruses avoid immune detection?

Answer 70

Limited cytolytic activity, persistent infection