Herpes virus and equine herpes virus -- L6 & L7 Flashcards
True or False: Many infections with herpesvirus occur asymptomatically
True
List some features of herpesvirus
- many infections with herpesvirus occur asymptomatically or are accompanied by a respiratory disease of varying serverity
- fragile in the environment
Describe the range of clinical presentations that herpes virus can cause:
- respiratory disease
- fetal death/abortion
- ulcerative skin lesions
- nervous system diseases
- lymphoproliferative diseases
How long does EHV-1 survive outside the host?
no longer than 1-2 weeks
TRUE OR FALSE: Is herpesvirus easily killed by disinfectants?
True
How is herpesvirus spread?
spread via mucosal contact or droplet
How does herpesvirus replicate?
replicates in the cell nucleus by inclusion bodies
Herpes virus _____ are easily _____?
virions are easily inactivated
Do herpes virus virions survive well outside the body?
No they do not and they are considered enveloped and fragile outside the body
TRUE OR FALSE: Herpesvirus is found in all mammals and bird species plus reptiles, amphibians, and oysters
TRUE
At least one major disease of each domestic animal species is recognised to be caused by a herpesvirus except for?
sheep
True or false: Many animal species are hosts to more than one herpesvirus
TRUE
A large and diverse family of dsDNA viruses
Herpes virus
List some herpesviral diseases of veterinary importance
- Equine upper respiratory disease / abortion /neurologic disease/veneral disease (equine herpesviruses)
- Cat‘flu’(feline herpes virus)
- Infectious bovine rhinotracheitis (IBR)
- Pseudorabies (Aujeszky’s)
- Malignant catarrhal fever
- Bovine mammilitis virus (BoHV-2)
- Marek’s disease (chickens)
- Infectious laryngotracheitis (chicken)
Viral genome is present, but only few (if any) genes are transcribed and there is NO production of infectious virus
Viral latency
Herpesviruses characteristically establish latency _____ primary infection.
AFTER
Where are the sites of latency?
typically lymphoid or neural tissues
What is it called when a virus is periodically reactivated and shed from latently-infected animals.
recrudescence
occurs even in the presence of circulating antiviral antibodies
recrudescence
recrudescence is generally associated with?
stressors such as crowding, other diseases, exhaustion, transportation, exposure to excessive UV light, exposure to extreme heat or cold
When herpesvirus is reactivated what happens?
Cell lysis with release of millions of progeny viruses
True or false: Viruses “invisible” to the immune system or No production of infectious virus happens when the virus is latent
TRUE
An immune response has ____ effect on latent virus i.e., it does not prevent _____ nor clears the virus from latently infected animals
little effect; recrudescence
5 limitations of the herpesvirus vaccine:
• Doesn’t prevent infection
• Doesn’t prevent establishment of latency
(or prevent recrudescence)
• Doesn’t completely stop shedding of virus
• Doesn’t induce long-lasting immunity
•no claim on prevention of EHM
TRUE OR FALSE: Herpesvirus vaccine isn’t useful to increase overall herd immunity
FALSE! It may be useful to increase overall herd immunity
Clinical signs of bovine herpesvirus 1?
- Fever, depression, inappetence
- Profuse nasal discharge (serous to mucopurulent)
- Hyperaemia and ulcers on nasal mucosa
- Early marked rhinitis and conjunctivitis
- Gastroenteritis (particularly in calves – often fatal)
- Occasional abortion
- Occasional mastitis
▪ Respiratory disease - Infectious bovine rhinotracheitis (IBR)
▪ Genital disease – Infectious pustular vulvovaginitis
▪ Keratoconjunctivitis
▪ Abortion
▪ Gastrointestinal disease in calves
These are all apart of?
Bovine herpesvirus 1
Who is affected by infectious bovine rhinotracheitis (IBR)
young cattle and deer
How is Infectious bovine rhinotracheitis (IBR) transmitted?
droplet transmission (+/- airborne)
How does Infectious bovine rhinotracheitis (IBR) replicate?
In nasal epithelium then lymph nodes and bronchial tree
What does Felid herpesvirus 1 cause?
Feline rhinotracheitis
What does Canid herpesvirus 1 cause?
canine neonatal death
what are the 2 forms of bovine mammillitis: BoHV-2
1) teats and udder only (seen in NZ)
2) generalized skin disease called pseudolumpyskin disease seen in Africa
Primarily a disease of pigs characterised by reproductive, respiratory and CNS signs
Suid herpesvirus 1: Aujeszky’s disease
True or false: Most other mammalian spp. (excluding primates) can become infected by direct or indirect contact with Suid-herpesvirus 1 shedding pigs
TRUE
___ is a dominant feature in secondary hosts (Suid herpesvirus 1)
pruritus
Mad itch and pseudorabies are caused by which herpesvirus
Suid herpesvirus 1
In adult pigs herpesvirus is usually ______ (but they may still shed the virus)
subclinical
T/F Suid herpesvirus 1 is usually fatal in secondary hosts?
True
Secondary hosts in suid herpes virus 1 are usually considered ____ hosts which means what?
Usually dead-end hosts – no further transmission
Infected piglets (< 3 weeks old) born to non-immune dams show ________ signs followed by incoordination, recumbency, convulsions and death (~100%) in suid herpesvirus 1
respiratory
Infection of non-immune pregnant sows can cause what to happen if they are infected by suid herpes virus?
foetal resorption
abortion (50% of sows)
stillbirths
birth of weak piglets
Incubation time of Gallid herpesvirus 1?
2-8 days
Clinical signs of Gallid herpesvirus 1?
Coughing, sneezing, ocular discharge, dyspnea, gasping, +/- bloody mucous, coughing blood
In what herpes virus do you see severe rhinotracheatis with formation of diphtheric membranes at post mortem?
Gallid herpesvirus 1: Infectious laryngotracheitis (ILT)
How is Gallid herpesvirus 1 transmitted?
Transmission via droplets inhalation or ingestion (less common)
Clinical signs of Gallid herpesvirus 2: Marek’s disease
• Enlargement of peripheral nerves • Sciatic:leg paralysis • Brachial:wing paralysis • Vagus: crop dialation and gasping • Enlargement of feather follicles with reddening of skin • Discoloration of the iris and blindness • Visceral tumors (liver, heart, spleen, gonads, kidney, proventriculus...)
How to control Gallid herpesvirus 2: Marek’s disease
Vaccination (1-day old birds) and Breeding resistant birds
Is subclinical infection common in Gallid herpesvirus 2: Marek’s disease
Yes spread by virus shedding
How do birds spread and transmit Gallid herpesvirus 2?
the virus is spread in dander from feather follicles and transmitted by inhalation
Malignant catarrhal fever virus (MCF) clinical signs:
high fever enlargement of peripheral lymph nodes mucopurulent nasal discharge photophobia ulcerated gums inflammation congestion erosion of mucosal surfaces dermatitis corneal opacity
How is Wildebeest-associated MCF (African form) caused?
Caused by alcelaphine herpesvirus type 1 (AHV-1)
Virtually all wildebeest calves are infected with Wildebeest-associated MCF by what age?
by 6 months of age
Sporadic disease of cattle, farmed deer (NZ), and bison
Sheep-associated MCF
are there clinical signs in Ovine herpes virus type 2 (OHV-2)?
not for sheep
Cows- lymphoproliferation of mucosal surfaces. Death in almost 100% of cases
How is MCF infection spread?
infection via oculonasal route
Incubation period of MCF?
variable
MCF death in almost ____% of cases
100%
MCF disease is associated with ______ infection of lymphocytes
LATENT
Two distinguishing characteristics of MCF?
lymphoproliferation and erosions of mucosal surfaces
Is there a vaccine available for MCF?
NO
How to control/prevent MCF?
good infection control practices, minimize contact with carrier animals (wildebeests in Africa, sheep in other parts of the world)
Does Suid herpesvirus 1: Aujeszky’s disease still exist in NZ?
NO eradicated in 1997
TRUE OR FALSE: MCF is present in sheep, cattle, deer
true
TRUE OR FALSE: infectious bovine rhinotracheitis (IBR) exists in NZ?
True but subset found here is the less virulent end of the scale
what belongs to family Alphaherpesviridae and order Herpesvirales
EHV-1 and EHV-4
The level of sequence identity at the amino acid level between EHV-1 and EHV-4 ranges from __% to __%.
55-96% so the two viruses cannot be distinguished antigenically by most of the routine serological tests.
How long is the respiratory incubation period for equine herpesvirus?
1-3 days so very short amount of time
What are the clinical signs of the EHV?
Upper respiratory disease: biphasic fever, depression, anorexia, lymphadenopathy, ocular and nasal discharges
can EHV affect athletic performance in horses?
YES
When do herpesviral abortions usually occur?
last trimester of pregnancy
What are abortion storms?
sporadic abortions
True or false: if the mare is affected by the equine herpesvirus and she aborts there are usually no clinical signs
TRUE
What is EHM?
equine herpesvirus myeloencephalopathy
True or false: EHM can be brought on suddenly or have a rapid progression
TRUE
Clinical signs of EHM:
Ataxia, paresis, urinary incontinence, cystitis, Vasculitis, thrombosis, haemorrhages in CNS
How to detect actively infected EHV-1 horses:
1) detection of virus in nasal secretions
2) detection of rising EHV-1 antibody titres
**if its latent there won’t be any nasal secretions!!!
How to detect latently infected horses:
1) Detection of viral DNA in latently infected cells
2) Detection of EHV-1 antibody in unvaccinated horse
TRUE OR FALSE: EHV-1 is a common infection that only sometimes results in overt clinical disease
TRUE
Foals are likely to acquire EHV-1 infection early in life from their dams, often in the presence of what?
of maternally derived antibody
EHV-1 infections may result in respiratory disease of various severity, but most are _____?
subclinical
Following primary EHV-1 infection, foals and horses become latently infected _____
for life
Latently infected horses can ______ the virus in the respiratory epithelium providing a source of infectious virus to others.
recrudesce
True or false: It’s easy to detect latently infected horses.
FALSE it’s very challenging
Dimorphism in the sequence of DNA polymerase, encoded by ORF30 is associated with increased _______, but other factors also play a role.
neurovirulence
How do you diagnose EHV-1 infection in respiratory diseases?
– Detection of EHV-1 in nasal swabs
– +/- rising antibody titres
How do you diagnose EHV-1 infection in Abortion/neonatal disease?
Detection of EHV-1 in fetal/neonatal tissues and/or placenta
How do you diagnose EHV-1 infection in EHM?
Difficult ante mortem
True or false: A single test can rule EHM in or out.
FALSE – No single test that could rule EHM in or out
is supportive and includes reduction of inflammation and prevention of secondary bacterial infections.
Treatment of EHM
Prognosis for non-recumbent EHM affected horses is?
good with appropriate supportive treatment.
Prognosis for recumbent EHM affected horses is?
poor
EHV-1 can circulate _____ among horses
sub-clinically
What are some positives to the EHV-1 vaccine?
• Reduce shedding of the virus • Reduce duration and severity of respiratory disease • Some help to prevent EHV-1 abortions
When should young horses be vaccinated fro EHV-1/4?
Young horses can be vaccinated following maternal antibody decline (6-9 months of age).
The initial dosing involves 2 doses given 2-4 weeks apart, followed by 6-12 monthly boosters as needed.
When should mares be vaccinated fro EHV-1/4?
typically three doses recommended
- either two 2-4 weeks apart before service followed by a booster in the 4-5th month
- or three doses during pregnancy (e.g. at 5th, 7th, and 9th months of gestation)
How to control EHV-1?
- EHV-1 vaccine
- good management
- sound infection control practices
What are some sources of the infectious virus in EHV-1?
– Aborted foetuses
– Close contact with horses shedding EHV-1 in nasal secretions
– Fomites
EHV-1 shedding in the nasal secretions can be up to ____ weeks and can be _______.
– Up to 3 weeks
– Can be intermittent
Venereal skin disease that affects the penis, prepuce, vulva or vagina
Equid Herpesvirus 3: equine coital exanthema
Is Equid Herpesvirus 3 uncommon in NZ?
YES!
What are the two equine gammaherpesviruses?
EHV-2 AND EHV-5
