Virology L8 next half Flashcards
RNA viruses
FLAVIVIRIDAE
Characteristics
§ Linear (+) sense ss or ds? RNA or DNA?
§ Enveloped or non-enveloped?
§ Surface proteins organized in shape?-like symmetry
§ Release by ?
§ Hosts: humans, ?
§ ** Transmission via vector (?, ticks) **
§ Flavus means ? -> hint: a color (Latin)
§ Diseases in humans include Japanese ?, Dengue fever, Hepatitis C virus, West Nile fever, ? fever, ? fever
RNA viruses
FLAVIVIRIDAE
Characteristics
§ Linear (+) sense ss RNA
§ Enveloped
§ Surface proteins organized in icosahedral-like symmetry
§ Release by exocytosis
§ Hosts: humans, mammals
§ ** Transmission via vector (mosquitoes, ticks) **
§ Flavus means yellow -> hint: a color (Latin)
§ Diseases in humans include Japanese encephalities, Dengue fever, Hepatitis C virus, West Nile fever, yellow fever, zika fever
West Nile Fever
§ Genus ?, species ? virus
§ Natural host: ?
§ Can cause fatal ? symptoms in humans (encephalitis meningitis, meningoencephalitis,
poliomyelitis, neuroinvasive disease)
§ Can cause severe ? or disease in ?
pic:
- ?% asymptomatic - human infection iceberg
- ? % west nile fever (v crude estimates)
- <1 % CNS disease (<0.1% of total infections)
- ZOONOTIC OR NOT?
- West Nile virus replicates in infected “?” musquitoes
- humans get infected when bitten by a mosquito carrying WNV. but, WNV doesn’t ? and can’t be spread back to biting ?
- ? are the amplifying hosts and can spread WNV across large geographic areas
- like humans, horses can also become with WNV, but they are also ? hosts and can’t spread the virus back to musquitoes.
West Nile Fever
§ Genus flavivirus, species west nile virus
§ Natural host: birds
§ Can cause fatal neurological symptoms in humans (encephalitis meningitis, meningoencephalitis,
poliomyelitis, neuroinvasive disease)
§ Can cause severe death or disease in horses
pic:
- 80% asymptomatic - human infection iceberg
- 20% west nile fever (v crude estimates)
- <1 % CNS disease (<0.1% of total infection)
for every case of illness involving the brain or spinal cord, ~ 150 total infections.
- ZOONOTIC OR NOT? YES
- West Nile virus replicates in infected “Culex” musquitoes
- humans get infected when bitten by a mosquito carrying WNV. but, WNV doesn’t replicate efficiently and can’t be spread back to biting mosquitoes
- birds are the amplifying hosts and can spread WNV across large geographic areas
- like humans, horses can also become with WNV, but they are also dead-end hosts and can’t spread the virus back to musquitoes.
FLAVIVIRIDAE
Bovine viral diarrhea (BVD) - IMP SLIDE!!!
§Genus ?, species Bovine viral ? virus
§ ? effect; direct effect on ? system & ?
§ BVD infection of susceptible dam results in persistent infected fetus -> ** ? ? animals ** recognize intra-cellular BVD virus particles as “?” and shed virus throughout ?
§ Significant economic disease of cattle
§ ** ? and non-? biotypes **
(1st one more viral one - causes embryonic death)
FLAVIVIRIDAE
Bovine viral diarrhea (BVD) - IMP SLIDE!!!
§Genus pestivirus, species Bovine viral diarrhea virus
§ immunosuppressive effect; direct effect on respiratory system & fertility
§ BVD infection of susceptible dam results in persistent infected fetus -> ** persistent infected animals ** recognize intra-cellular BVD virus particles as “self” and shed virus throughout life (via urine, faeces, milk, semen, saliva, mucus, nasal excretions)
§ Significant economic disease of cattle
§ ** cytopathic and non-cytopathic biotypes ** (cytopathic is the more virulent one, and that is the virulent bio type, how the infection follows its course and we will have a vertical transmission here for BVD
- So the infection of, for example, a susceptible mother animal can result in an infection of the fetus.
- And depending on the time of infection during pregnancy, you can also have a persistently infected animal)
top pic:
- So if you have an animal that is not pregnant and gets infected by a noncytopathic or a cytopathic biotype, it may develop diarrhea? may develop respiratory signs.
- if infection during pregnancy then it can impact the fetus.
- in the early stages of pregnancy, if we have a cytopathic biotype meaning a virulent one it will lead to embryonic death
- if we have a cytopathic biotype that infects at later stages of pregnancy then it can also lead to abortion and the fetus usually are malformed so they can be born alive but w malformations
- if we have infections with non-cytopathic one then special case, i.e. if infection occuring between day 30 and 110 of the gestation period in animal,
at this point fetus doesn’t have fully developed immune system So it will not recognize this non cytopathic biotype as something strange and it’s not as virulent as the cytopathic type where you have an immediate impact on the fetus.
thus the calf is born alive but becomes immunotolerant and secretes non-cytopathic virus all the time but u won’t have the immune response from the fetus, considers it “Self”
- another problem is a mutation occuring in the virus from non-cytopathic to the virulent cytopathic biotype which leads to fatal hemorrhagic disease or more specifically, mucosal disease.
- And the mucosal disease is a fatal infection.
So chances of these calves to reach adulthood and entering production cycles are quite low.
pic: if we have a persistently infected calf constantly shedding the virus, it again can lead to an infection of a pregnant female on the cattle herd and it can all start over again.
So if we can have another persistently infected calf being born, especially when that happens at that specific time of gestation.
non-pregnant animals can develop acute infections such as diarrhea, respiratory signs
Calves that are exposed to another persistently infected animal will often also develop a little bit of diarrhea, pneumonia etc. and also herd bull may become acutely infected and then expose cows while breeding (semen -> enter in breeding cycle again)
- THUS to solve the problem have to track down the persistently infected calf and one way to do it is to check gums - bleeding all over mucosa, first seen in oral cavity also seen in the conjunctiva, intestinal layer, lots of ulcerations, the interdigital space, and then gradually all over in the body, but usually internal on the mucosal layer.
bottom image:
- to show you what can happen if there is an infection with cytopathic or noncytopathic.
- recall: cytopathic will lead to fetus death or abortion with malformations, congenital defects, as we call it, the persistently infected calves, or when we have that specific window of infection.
- If the infection happens at the END of the gestation in your mother animal, your calf will have DEVELOPED an IMMUNE response and it will fight of the infection.
- If you’ve done the test serology, it will have antibodies against the noncytoplasmic bio type of bovine viral diarrhea virus.
- So here, right at the end the calf will be born seropositive. So it produces antibodies, but it’s not a persistently infected animal.
Bovine viral diarrhea (BVD)
§Virus is poorly transmitted from ? infected animals but efficiently transmitted from Pi animals
Clinical signs:
§ Infection in non-pregnant cattle (young animals): ? clinical course, fever, ?, ? on lips, muzzle oral cavity
§ Infection in pregnant cattle ~ fetus age
§ Persistent infection in calves: fail to thrive; ? disease when co-infected with cytopathic virus (profuse watery diarrhea, nasal discharge, emaciation, ? stomatitis, death)
§ Diagnosis: Clinical signs, history and laboratory diagnosis (find PI animals!)
§ Detection of viral antigen in ear notch samples
§ Serology–ELISA
Prevention and control:
§ ? to reduce clinical disease; eliminate ? animals
Bovine viral diarrhea (BVD)
§Virus is poorly transmitted from acutely infected animals but efficiently transmitted from Pi animals
Clinical signs:
§ Infection in non-pregnant cattle (young animals): mild clinical course, fever, diarrhea, ulcerations on lips, muzzle oral cavity
§ Infection in pregnant cattle ~ fetus age
§ Persistent infection in calves: fail to thrive; mucosal disease when co-infected with cytopathic virus (profuse watery diarrhea, nasal discharge, emaciation, ulcerative stomatitis, death)
§ Diagnosis: Clinical signs, history and laboratory diagnosis (find PI animals!)
§ Detection of viral antigen in ear notch samples
§ Serology–ELISA
Prevention and control:
§ Immunization to reduce clinical disease; eliminate PI animals
- diagnosis: detection of viral antigen in ear notch samples and serology used in combination.
- especially serology is not to be used as a stand-alone test when we have implemented a vaccination strategy.
- So we have immunization or vaccination strategies to reduce the number of cases of clinical disease to start off with the adult animals.
Zika Fever
§ Genus ?, species ? virus
§ Fever, ? eyes, rash, ? pain, ?
§ Transmission: by day-time active ? (Aedesaegypti), ?
Zika Fever
§ Genus Flavivirus, species zika virus
§ Fever, red eyes, rash, joint pain, headache
§ Transmission: by day-time active moaquito (Aedesaegypti), sexually
Togaviridae
Characteristics
§ Linear (+)sense ss or ds? RNA or DNA?
§ enveloped or non-enveloped?
§ Release by ?
§ Hosts: humans, ?, birds, ?
Epidemiology
§ Genus ?: ? transmission
§ Disease: ? rubella (humans
§ Genus Alphavirus: ? bite
§ Diseases: Eastern equine ?,
?
Togaviridae
Characteristics
§ Linear (+)sense ss RNA
§ enveloped
§ Release by budding
§ Hosts: humans, mammals, birds, mosquitoes (musquitoes carrying virus from reservoirs = rodents, birds and others)
Epidemiology
§ Genus Rubivirus: respiratory transmission
§ Disease: congenital rubella (humans
§ Genus Alphavirus: arthropod bite
§ Diseases: Eastern equine encephalitis,
chikungunya
Togaviridae
§ ** Arbovirus ** = ?-borne virus = virus that replicates in and is transmitted by arthropods
§ These viruses maintain in nature by going through a cycle between a ? and a ?
§ Most arboviruses are ** ? ** and have a maintenance enzootic cycle in birds, ?, non-human ?
- Enzootic = ? in animal population
- epizootic = ? outbreak of a disease in animal population
(recall: mechanical vectors, think about lice in POX, but there the Virus doesn’t replicate inside the lice it’s a mechanical transmission
for Arboviruses through Arboviruses and they go into cells of the mosquito and replicate in there.
So often these viruses are maintained by natural cycles between the host and the vector host species could be birds, reptiles and rodents because of the presence of the mosquito there as a vector, many of these will be ZOONOTIC!
So many arboviruses are zoonotic and can be transmitted to us humans.
epizootic: So the way it fluctuates between different mosquitoes and let’s say two host species, So if we have an epizootics cycle, a higher number of viruses will be circulating in the population here. It will often be continued circulating between birds and it can end up in dead end hosts.
FYI: It’s also here Eastern Equine encephalitis, just like West Nile virus, is infecting horses and humans, but they’re dead end hosts so musquito cannot take virus from us.
Togaviridae
§ ** Arbovirus ** = arthropod-borne virus = virus that replicates in and is transmitted by arthropods
§ These viruses maintain in nature by going through a cycle between a host and a vector
§ Most arboviruses are ** zoonotic ** and have a maintenance enzootic cycle in birds, rodents, non-human primates
- Enzootic = endemic in animal population
- epizootic = epidemic outbreak of a disease in the animal population
Picornaviridae
Characteristics
§ Linear (+)sense ss or ds? RNA or dna?
§ Non-enveloped or enveloped?
§ Release by ?
§ Hosts: ?
Cell tropism - REMEMBER THIS!!
§ ?: gastrointestinal tract
§ Species ?: upper ? tract
(“common cold”)
§ Aphtoviruses: ?
§ Hepatoviruses: ?
§ Cardioviruses: ? tract (respiratory) primary site of infection, then heart and CNS
Picornaviridae
Characteristics
§ Linear (+)sense ss RNA
§ Non-enveloped
§ Release by cell lysis
§ Hosts: vertebrates
Cell tropism - REMEMBER THIS!!
§ Enteroviruses: gastrointestinal tract
§ Species Rhinovirus: upper respiratory tract
(“common cold”)
(entero = intestines)
§ Aphtoviruses: epithelium
§ Hepatoviruses: liver
§ Cardioviruses: GI tract (respiratory) primary site of infection, then heart and CNS
An exception to the rule of tropism is our common cold which is a rhinovirus and it belongs to enteroviruses which affect GI tract but rhinovirus doesn’t infect GI tract rather, the respiratory tract (common cold)
PICORNAVIRIDAE
Foot and Mouth Disease
§ Genus ?, species Foot and ? virus
§ Host: cattle, ?, sheep, ? (all species of deer, antilope, giraffe and elephant also susceptible)
§ Highly infectious via ? and secretions of infected animal
§ High fever, ? in mouth and feet, high ? in young animals
§ Endemic in most of ?, Middle East and parts of ?
PICORNAVIRIDAE
Foot and Mouth Disease
§ Genus aphtovirus, species Foot and mouth virus
§ Host: cattle, pigs, sheep, goat (all species of deer, antilope, giraffe and elephant also susceptible)
§ Highly infectious via excretions and secretions of infected animal
§ High fever, blisters in mouth and feet, high mortality in young animals
§ Endemic in most of africa, Middle East and parts of asia
PICORNAVIRIDAE
Poliomyelitis
§ Genus ?, species ?
§ Host: ? (young children!)
§ Chimpanzees and Old World Monkeys can be infected ?
§ Transmission: ?-oral
§ Multiplies in ? -> viremia -> central nervous system i.e. if its symptomatic CNS: paralytic disease -> ? (<> 95% asymptomatic)
§ Very rapid ? -> overwelming the ? system
Poliomyelitis
§ Genus enterovirus, species poliovirus
§ Host: humans (young children!)
§ Chimpanzees and Old World Monkeys can be infected experimentally
§ Transmission: fecal-oral
§ Multiplies in intestines -> viremia -> central nervous system i.e. if its symptomatic CNS: paralytic disease -> deformations (<> 95% asymptomatic)
§ Very rapid replication -> overwelming the immune system
RNA VIRUS (not a picornaviridae)
Caliciviridae
Characteristics
§ Linear (+)sense ss or ds? RNA
§ Non-enveloped or enveloped?
§ Release by cell lysis
§ Not well studied, difficult to grow in cell cultures and no suitable animal models
§ Epidemiology
§ Genus ?: airborne transmission (cats) -> ? disease
§ Genus ?: direct contact (rabbits) -> hemorrhagic disease
§ Genus ?: ?-oral transmission (humans, mammals) -> acute gastroenteritis
** (very ?) **
Caliciviridae
Feline calicivirus
§ Genus ?, species ? calicivirus
§ Important viral cause of ? infection in cats
§ Cheetahs can be ? infected
§ ? infections possible
§ Symptoms: sneezing, ? discharge, ?, ?
RNA VIRUS (not a picornaviridae)
Caliciviridae
Characteristics
§ Linear (+)sense ss RNA
§ Non-enveloped
§ Release by cell ?
§ Not well studied, difficult to grow in cell cultures and no suitable animal models
§ Epidemiology
§ Genus vesivirus: airborne transmission (cats) -> respiratory disease
§ Genus lagovirus: direct contact (rabbits) -> hemorrhagic disease
§ Genus Norovirus: fecal-oral transmission (humans, mammals) -> acute gastroenteritis
** (very contagious) **
Caliciviridae
Feline calicivirus
§ Genus Vesivirus, species Feline calicivirus
§ Important viral cause of respiratory infection in cats
§ Cheetahs can be naturally infected
§ latent infections possible
§ Symptoms: sneezing, nasal discharge, stomatitis, pneumonia
