Neurological Viruses

Question 1

what types of virus classes are transmitted via arthropod transmission?

Answer 1

selected togaviruses and flaviviruses

Question 2

what are some common arthropod vectors?

Answer 2

• mosquitos: culiseta, aedes, culex

- ticks

Question 3

what are some common arthropod reservoirs?

Answer 3

birds and small mammals

Question 4

T/F: transmission requires replication in the vector

Answer 4

T

Question 5

geographic location determined by ______ and _______ habitat

Answer 5

vector, reservoir

Question 6

describe the eastern equine encephalitis (EEE) and venezuelan equine encephalitis (VEE)

Answer 6

• togaviridae
• genome: (+)ssRNA
• virion: enveloped
• proteins:
  
  • E1&E2: cell attachment & entry
  • capsid protein
  • carious non-structural proteins

** non-structural proteins important at first and structural proteins important later

Question 7

where is replication at for EEE and VEE?

Answer 7

• no nuclear access
• goes thru ER (picks up envelope material)
• RNA packaging scheme then buds off surface

Question 8

how do EEE and VEE enter a cell?

Answer 8

• virus introduced through the bite of an infected arthropod
• infect cells locally and/or carried by Langerhans cells to LN
• replication and release into the blood stream
• infection in other target organs such as the CNS
  
  • method of crossing blood-brain barrier is unknown

Question 9

what is the EEE incubation period?

Answer 9

4-10 days

Question 10

what are the symptoms of the EEE systemic disease?

Answer 10

chills, fever, malaise, arthralgia, myalgia

lasting 1-2 weeks full recovery

Question 11

what are the symptoms for the EEE encephalitis disease?

Answer 11

fever, headache, irritability, restlessness,vomiting, diarrhea, convulsions, and coma

Question 12

do people die from the encephalitis infection of EEE and if so how prevalent is mortality?

Answer 12

1/3 encephalitic cases die from the disease 2-10 days after onset

Question 13

T/F: those who recover from the encephalitis infection of EEE can have long term sequelae

Answer 13

T: seizures, personality disorders, paralysis

Question 14

is there a vaccine for EEE and VEE? describe

Answer 14

• a single vaccine is available (TC-83)
• live attenuated (TC-83)
• inactivated (C-84)
• only provided to at risk military personnel and researchers
• partially effective against inhalation challenge in primates

Question 15

is there any treatment for EEE and VEE?

Answer 15

no treatment just supportive care

Question 16

what types of prevention are there for EEE and VEE?

Answer 16

• mosquito control strategies

- mosquito repellant

Question 17

where in the US is the most prevalence for EEE?

Answer 17

east coast

Question 18

what is the incubation period for the west nile virus?

Answer 18

2-14 days and most persons (80%) have asymptomatic infections

Question 19

illness from west nile virus occurs in ~20% of cases, what are the symptoms?

Answer 19

fever, headache, fatigue for 3-6 days

Question 20

can west nile virus ever become neuroinvasive?

Answer 20

yes, <1%

• aseptic meningitis, encephalitis, flaccid paralysis, altered mental state, tremors
• 50% of survivors have sequelae 12 mos later

Question 21

is there a vaccine for west nile virus?

Answer 21

no

Question 22

is there treatment for west nile virus?

Answer 22

no

Question 23

what can be done to prevent west nile virus?

Answer 23

• mosquito control strategies

- mosquito repellant

Question 24

where is west nile the most prevalent in the US?

Answer 24

across entire US because range for birds (vector) is wider than mosquitos

Question 25

what type of virus is rabies virus?

Answer 25

• rhabdoviridae
• genome: (-)ssRNA
• virion: enveloped
• proteins:
  
  • nucleoprotein
  • phosphoprotein
  • matrix
  • glycoprotein (attachment & entry)
  • polymerase

Question 26

does rabies have broad tropism?

Answer 26

yes, the glycoproteins on surface can bind many cell receptors so can infect many

Question 27

where does rabies replicate inside the cell?

Answer 27

cytoplasm

Question 28

T/F: the order in which the rabies virus genome is composed dictates the abundance of transcripts and proteins

Answer 28

T

Question 29

Binding of ________ to RNA triggers rabies virus genome replication

Answer 29

nucleoprotein: makes (+) strand–>progeny genome production

Question 30

how is rabies virus transmitted?

Answer 30

bite of infected animal

15% of bites cause disease
60% if on face or head

Question 31

what is the reservoir for rabies virus?

Answer 31

bats, skunks, raccoons, dogs in developing countries

Question 32

what is the incubation period for rabies virus?

Answer 32

1-3 mos.
longer is possible, though rare
depends on location of bite

Question 33

how is rabies spread?

Answer 33

• replicates locally until it finds neurons
  
  • at site of bite, moves up neurons to brain and spreads back to peripheral nervous system
  • goes to salivary glands and replicates

Question 34

what are the symptoms of rabies virus?

Answer 34

• prickling or itching where bitten, fever, headache
• hydrophobia: difficulty swallowing, even saliva, leads to “foaming at the mouth”
• cerebral dysfunction, anxiety, confusion, delirium, hallucinations, and insomnia

Question 35

what is the outcome of rabies virus?

Answer 35

• once symptoms appear, disease is nearly always fatal

- only 10 documented survivals, only 2 of those had no history of previous prophylaxis

Question 36

is there a rabies vaccine?

Answer 36

yes

Question 37

is post-exposure prophylaxis possible for rabies?

Answer 37

• should be administered immediately for bites that break skin
• 4 doses: immediate, 3, 7, 14 days
• should also receive immunoglobulins (RIG)

Question 38

does vaccination of dogs and wildlife help spread?

Answer 38

of course