Virology

Which of the following are viral non-structural proteins? Choose all correct answers (there may be more than one). a. Integrase. b. Reverse transcriptase. c. Hyaluronidase. d. Hexokinase. e. Peplomerase.

a,b

Which of the following disease manifestations is least typical of herpesvirus infections in mammals? a. Respiratory disease. b. Hepatitis. c. Central nervous system changes. d. Lymphoproliferative disorders. e. Ulcerative skin lesions.

b

A proliferative lesion in the picture below is characteristic of infection with: a. Herpesviruses. b. Adenoviruses. c. Poxviruses. d. Circoviruses. e. Parvoviruses.

c

One of the characteristics common to all herpesviruses is their ability to establish latency in their hosts. Choose the least true statement a.Detection of latently infected animals is difficult, as these animals appear clinically normal and are not shedding the virus. b.Latently infected animals can re-activate the virus when stressed. As such, they can develop herpesvirus-associated disease even if not exposed to a source of an infectious virus (e.g. a clinically sick animal). c.Latently infected animals can be detected by serological testing, as they are always positive for anti-herpesviral antibody, even though they are not shedding the virus. d.Latently infected animals are not infectious. However, they do become infectious when they re-activate the virus. e.Vaccination against herpesviruses is typically ineffective in preventing development of latency. e. establish latency in their hosts. Choose the least true statement describing the effects of latency on diagnosis and control of herpesviral diseases:

c

Viruses posses the following characteristics: a. Viruses contain both DNA and RNA. b. The viral nucleic acids are enclosed within the nucleus inside the viral particle. c. The viral nucleic acids are used to generate viral mRNA within the host cell. Viruses contain ribosomes, which are released into the host cell and used for viral protein synthesis. d. e. All viruses can be cultured in vitro in the appropriate cell culture system.

c

You are presented with a young parrot that has recently lost some of its feathers. The owner also noticed that the bird's beak looks overgrown and shiny. Infection with what virus is most consistent with the above clinical signs? a. Psitaccine parvovirus. b. Avian papillomavirus. c. Psitaccine beak and feather disease virus. d. Avian adenovirus type 1. e. Gallid herpesvirus type 2.

c

Which of the following viruses is least likely to cause neurologic disease in a horse? a. Equid herpesvirus type 1. b. Borna disease virus. c. Western equine encephalitis virus. d. Equine influenza virus. e. West nile virus.

d

Which of the following viruses typically produce only localised infections without systemic spread: a. Feline panleukopenia virus. b. Equid herpesvirus type 1. c. Canine parvovirus. d. Orf virus. e. African swine fever virus.

d

Which of the following viruses typically produce only localised infections without systemic spread: a. Feline panleukopenia virus. b. Equid herpesvirus type 1. c. Canine parvovirus. d. Orf virus. e. African swine fever virus.

d

A cytopathic effect (CPE) is sometimes observed when cultivating viruses in vitro. Which of the following statements about CPE is least correct? a.Some kinds of virus cause a characteristic CPE. For example, herpesviruses tend to cause formation of syncytia. b.Dead cells, killed by the virus, tend to look large, angular, and paler than surrounding healthy, uninfected cells. c.It may take weeks for a CPE to develop. Multiple cell passages may have to be done before CPE can be observed. d. Some kinds of virus grow very well in cell culture but cause no CPE whatsoever. e.If CPE develops very rapidly, it may be difficult to distinguish it from cytotoxicity due to a toxic substance in the clinical specimen (i.e., the inoculum).

e

A serum sample from a mare that aborted due to a suspected Equid herpesvirus 1 infection tested positive for EHV-1 antibodies in a virus neutralisation test. Choose the incorrect interpretation of this result: a. The positive result confirms that the mare aborted due to EHV-1 infection. b.The mare might have aborted due to the EHV-1 infection, but in order to confirm a recent EHV-1 infection a four-fold rise in titre between the acute and convalescent serum samples would have to be demonstrated. c.The positive result indicates that the mare has been likely exposed to EHV-1 at some point in the past, but tells us little about the timing of infection. d.It is possible that the mare has never been infected with EHV-1, as the positive serum titre to EHV-1 may have resulted from either vaccination or infection with an antigenically similar virus EHV-4. e.The mare has been exposed to either EHV-1 or EHV-4 at some point in the past. These two viruses cannot be distinguished serologically in a neutralisation test.

a

Antiviral drugs inhibit specific steps in viral replication. a.true b.false

a

Enveloped viruses are typically fragile and easily killed outside their hosts a.true b.false

a

Myxomatosis causes severe generalised disease in European rabbits, but only localised benign fibromas in American rabbits. a. True b. False

a

Orf virus can be transmitted between susceptible animals via fomites a.true b.false

a

Orf virus can infect humans a. True b. False

a

Poxviruses typically cause localized skin infections a. True b. False

a

Some poxviruses can establish viremia followed by generalized disease a. True b. False

a

Which of the following viruses infect invertebrate hosts? a. African swine fever virus. b. Canine adenovirus type 1. c. Feline herpesvirus type 1. d. Orf virus. e. Porcine circovirus type 2.

a

Which of these stages in the viral replication cycle is least likely to be targeted by antiviral drugs? a. Adsorption. b. Attachment. c. Uncoating. d. Synthesis. e. Release.

a

You are called to investigate an abortion "storm" that is occurring in a mob of heavily-pregnant mares. On close questioning, you learn that a 'new' mare has recently been introduced from another part of the country. Which of the following herpesviral causes should be at or near the top of your differential list? a. Equid herpesvirus type 1. b. Equid herpesvirus type 2. c. Equid herpesvirus type 3. d. Equid herpesvirus type 4. e. Equid herpesvirus type 5.

a

Which of the following statements about viral structure are true? Choose all correct answers (there may be more than one). a. Structural symmetry facilitates virion self-assembly. b. Cubic symmetry is a synonym for icosahedral symmetry. Individual virus families contain viruses of helical or icosahedral symmetry, but not both. c. d. Virions with complex symmetry have both helical and icosahedral symmetry. e. Helical symmetry is a feature of the viral nucleocapsid, not of the envelope.

a,b,c,d

Which of the following statements are true of alphaherpesviral latency? Choose all correct answers (there may be more than one). During latency, virus particles cannot be detected during any routine diagnostic test. a. b. Because of latency, measurement of antiviral antibodies is uninformative. c. There may be no viral protein whatsoever in the host's body during latency. d. During latency, virus can nevertheless be transmitted from host to host. e. Latency is most often achieved in nerve ganglia and lymphocytes.

a,b,c,e

Which of the following are characteristic features of poxviruses? Choose all correct answers (there may be more than one). a. Enveloped DNA viruses. b. Intracytoplasmic replication. c. Long-term carrier state after recovery. d. Evolve more rapidly than most other viruses. e. Complex structural symmetry.

a,b,d

Which of the following poxviral diseases is not known to be zoonotic? Choose all correct answers (there may be more than one). a. Cowpox. b. Pseudocowpox. c. Bovine papular stomatitis. d. Parapoxvirus infection of red deer in New Zealand. e. Monkeypox.

a,b,e

A kitten with upper respiratory disease is most likely to be infected with which of the following viruses: a. Feline immunodeficiency virus. b. Feline herpesvirus. c. Feline coronavirus. d. Feline astrovirus. e. Feline infectious peritonitis virus.

b

A single serum sample positive for antibody to a virus indicates that the animal from which the blood was collected had been recently infected with this virus. a.true b.false

b

Killed vaccines are safer and as such, killed vaccines are more commonly used in veterinary medicine than live vaccines. a.true b.false

b

One of the characteristics common to all herpesviruses is their ability to establish latency in their hosts. Choose the best statement describing the relationship between the host and a herpesvirus in a latent stage: a. During latency there is a very limited production of progeny viruses. b.During latency there is no production of progeny viruses, but limited transcription of the viral genome can occur. c. All herpesviruses establish latency exclusively in neural tissues. d.Once the virus enters a latent stage, it can be reactivated only if the host becomes re-infected with the same herpesvirus. e.Vaccination against herpesviruses is typically effective in preventing development of latency.

b

Poxviruses do not survive well in the environment. a. True b. False

b

Resistance to antiviral drugs is very rare, as viruses cannot change as rapidly as bacteria. a.true b.false

b

Soluble CD4 has been used experimentally as an anti-HIV drug and may yet prove useful in veterinary medicine. Which of the following stages in the virus replication cycle is it thought to target? a. Adsorption. b. Attachment. c. Uncoating. d. Synthesis. e. Release.

b

The samples for virological investigation should be transported to the laboratory: a.As soon as possible, preferably within 24 hours of collection. The samples should be put in a freezer immediately after collection and then thawed when ready for transport. The samples should be transported cold with ice packs. b.As soon as possible, preferably within 24 hours of collection. The samples should be kept cold, but not frozen after collection and during transport. c.Within a week of collection, providing they are kept in a fridge. d.As soon as possible, preferably within 24 hours of collection. If the samples are transported to the laboratory soon after collection there is no need to maintain the cold chain during transport. e.Any time after collection as long as the samples are maintained in the fridge. If the samples were collected using sterile technique all viruses will survive in the fridge for extended periods of time.

b

Which of the following is least true of Malignant catarrhal fever in New Zealand? a. It occurs sporadically. b. It is caused by Alcelaphine herpesvirus type 1. c. It features a characteristic vasculitis. d. It is most important in farmed red deer. e. It is epidemiologically linked to contact with sheep.

b

Which of the following viruses is least resistant to adverse environmental conditions: a. Canine parvovirus. b. Equid herpesvirus type 1. c. Orf virus. d. African swine fever virus. e. Bovine papillomavirus.

b

You are asked to advise on biosecurity measures to control the spread of respiratory viruses in a cattery. Which of the following statements is least correct? a.Feline calicivirus and Feline herpesvirus are the two most common respiratory viruses of cats. b.Both viruses are fragile in the environment and don't survive well outside their hosts. c. Both viruses can be transmitted by aerosol. d. There are vaccines available for both viruses. e. Asymptomatic infections can occur with both viruses.

b

You are called to investigate a drop in production levels at a local poultry farm. When you arrive, you notice a large number of misshapen eggs, as shown in a picture below. Infection with which virus should be on your list of differentials? a. Poxvirus. b. Adenovirus. c. Parvovirus. d. Herpesvirus. e. Circovirus.

b

You are called to investigate an abortion "storm" that is occurring in a mob of pregnant mares. On close questioning, you learn that several horses have also been recently showing signs of respiratory disease. You also learn that the "colds" and abortions seem to have started soon after two of the mares had been inseminated with semen from a Standardbred stallion that had not been used by the owners before. Which of the following causes should be on the top of your differential list? a. Equid herpesvirus type 4. b. Equine arteritis virus. c. Equine adenovirus. d. Equine herpesvirus type 2. e. Equine rhinitis virus.

b

Laboratory results of virus isolation are usually available: a.Within 24-48 hours. This is how long it takes for viral colonies to become visible on agar plates. b.Within 2-3 days for positive samples, but it may take up to 1 week for negative samples, as these are typically passaged in the appropriate cells 2-3 times before being reported as negative. c.Within 1-3 weeks for positive samples, but it may take up to one month or longer for negative samples, as these are typically passaged in the appropriate cells 2-3 times before being reported as negative. d.Within 24-48 hours, as viruses multiply very fast and typically millions of viruses are produced from one infected cell within hours. e.Within 1 week for negative samples, but it may take longer for positive samples, as the viruses cultured would have to be further identified.

c

Which of the following is least useful as a basis for classifying viruses into families? a. DNA or RNA genome. b. Double-stranded or single-stranded genome. c. Intranuclear or intracytoplasmic inclusion bodies. d. Helical, icosahedral, or complex structural symmetry. e. Enveloped or non-enveloped virions.

c

Which of the following is the least important reason why it was possible to eradicate smallpox from the world? a. ONE (1) stable serotype of the virus exists b. Smallpox has a long incubation period. c. Animal reservoir populations are well characterised. d. Smallpox is easily diagnosed. e. The period of infectivity begins after the end of the incubation period.

c

Which of the following statements about viral genomes is least true? a.Most DNA virus families have double-stranded genomes. b.Some RNA viruses have segmented genomes, but there are no DNA viruses with segmented genomes. c. There are no known RNA viruses with circular genomes. d. DNA virus genomes vary in size much more than do RNA virus genomes. e. There are no known RNA viruses with double-stranded genomes.

c

A large sheep farm in central Otago has had problems with scabby mouth in lambs each year for the last 4 years. They do not vaccinate against scabby mouth on this farm. The most likely explanation for the recurrent, relatively severe problems on this farm is: a.Persistently-infected ewes are acting as a source of the virus to new lambs each year. b.The virus is maintained in a rodent population on this farm and is periodically spread to lambs. c.Rams are transmitting the virus venereally to ewes and the ewes are passing the infection on to their lambs. d.The pastures and food troughs are contaminated with the virus, which is surviving outside each winter e.An unusually hardy virus variant has evolved on this farm.

d

Choose the best answer to finish the sentence: Swabs for virological investigation should be collected... a.Into a commercially available aerobic bacteriological swab - the medium provided with these swabs is suitable for both viral and bacteriological samples. b.Into a commercially available anaerobic bacteriological swab - the medium provided with these swabs is suitable for both viral and bacteriological samples. c.Dry into a sterile container (e.g. red top blood tube), so that any viruses present will not be diluted by the medium. d.Into a viral transport medium, which contains proteins to stabilize the virus and antibiotics to prevent bacterial growth. e.Into a sterile EDTA blood tube if the swab contains bloody discharge, so that it won't coagulate during transport to the laboratory.

d

The fish in the picture below is most likely infected with: a. A fish herpesvirus. b. An asfarvirus. c. A circovirus. d. An iridovirus. e. A poxvirus.

d

The main advantage of using virus isolation over the molecular based diagnostic assays such as PCR is that: a. Virus isolation is quicker than PCR. b. Virus isolation is cheaper than PCR. Virus isolation requires less sophisticated equiment and fewer skills than more advanced tests such as PCR. c. d. Unlike PCR, virus isolation demonstrates the presence of live virus in the sample. e.Unlike PCR, virus isolation provides immediate definitive identification of the virus, based upon the type of a cytopathic effect (CPE) produced in cell culture.

d

What kind of vaccine is licensed in New Zealand to prevent Orf? a.Modified live (attenuated) b. Adjuvanted, killed whole virus. c. Adjuvanted, viral subunit. d. Live, fully virulent virus. e. Recombinant avipox virus.

d

Which of the following is not a well recognised consequence of equid herpesvirus 1 infection? a. Abortion. b. Encephalomyelitis. c. Upper respiratory disease. d. Genital mucosal ulcerations. e.perinatal foal mortality

d

Choose the best option from the following. Herpesviruses: a. Typically cause a short illness followed by recovery and elimination of the virus. b.Stimulate solid (possibly life-long) immunity. Recovered animals are refractory to subsequent herpesviral infections. c.Establish a life-long infection in their hosts, with a constant low-level production of infectious virus. d.Are very resistant in the environment and as such, are easily transmitted by fomites over extended areas. e. Typically establish a life-long infection due to their ability to become latent.

e

Choose the least correct statement regarding Pseudorabies a. It is caused by Suid herpesvirus type 1. In dogs, it presents with clinical signs similar to rabies with incoordination, paralysis and convulsions. b. Adult swine infected with the Pseudorabies virus typically do not develop severe disease, but may abort. c. d. Dogs can become infected via ingestion of infected raw pig meat. e. It is a zoonotic disease.

e

Choose the least correct statement regarding the attachment of the virus to the host cell: a. Attachment is necessary for viral entry into the cell. b.Attachment step is one of the important determinants for viral tissue tropism and host range. c. Attachment relies on specific binding between viral and host proteins. d. Attachment is immediately followed by penetration of the virus into the host cell. e.Attachment step cannot be blocked as viruses typically use a wide variety of host receptors for attachment and entry.

e

In general, poxviruses can use the following portals of entry: a. Faecal-oral route. b. Skin with compromised integrity (e.g. skin abrasions). c. Respiratory route (via aerosols). d. Blood via mechanical vectors. e. Portals listed in b, c, or d.

e

The term "viral virulence" relates to: a. The ability of the virus to cause disease in its natural host species. b. The ability of the virus to cause cytopathic effects (CPE) in cell culture. c. The ability of the virus to cause disease in humans. d. The ability of the virus to spread systemically and infect a variety of tissues. e. The ability of the virus of cause disease in a specified host.

e

Which of the following clinical presentations is least typical of herpesviral infection a. Encephalitis. b. Ulcerative skin lesions. c. Abortion. d. Upper respiration disease. e. Pancreatitis.

e

Which of the following is the most commonly and widely used method for the cultivation of mammalian viruses? a. Organ cultures. b. Experimental animals. c. Primary cell cultures. d. Secondary cell cultures. e. Continuous cell lines.

e

Which of the following poxviruses has an unusually broad host range? a. Myxoma virus. b. Lumpy skin disease virus. c. Variola virus. d. Swinepox virus. e. Cowpox virus.

e

Which of the following stages in the virus replication cycle is the drug Tamiflu thought to target? a. Adsorption. b. Attachment. c. Uncoating. d. Synthesis. e. Release.

e

Which of the following statements about virus size and complexity is most true? a. The smallest viruses are smaller than viroids. b. The largest viruses are about as complex as Escherichia coli. c. The largest viruses can replicate independently of living cells. d. The smallest viruses consist only of protein. e. The smallest viruses are larger than prions.

e

You are a veterinarian accompanying a large group of sheep that is being shipped from New Zealand to the Middle East in a vessel that has previously been used for the shipment of sheep in other parts of the world. 28 days into the journey, 20% of these sheep have developed fever, generalised, raised skin lesions, and severe systemic illness. So far, about 25% of affected animals have died or required euthanasia on humane grounds. You suspect a viral infection. The most likely differential diagnosis at this stage is: a. Generalised orf. b. Ectromelia. c. Variola. d. Contagious ecthyma. e. Sheep pox.

e