SCRAPIEDRH. SRUTI LISTRA ADRENALIN, M.SC.

30 MARET 2020

SCRAPIE

Caused by prion.

The prototypic prion disease, scrapie, was first recognized in England in 1732, and a report from 1750 clearly

describes scrapie as an infectious and consistently fatal disease of sheep.

The name reflects the characteristic scratching observed in diseased animals.

Prions modified host protein molecules, not associated with detectable nucleic acid, that are transmissible and

induce fatal neurologic disease.

PrPsc generated from the normal isoform of the protein PrPc causes neurologic disease by unknown

means.

PRION

PrPsc protein is very resistant to many environmental insults, chemicals, and physical conditions that would

destroy any virus or microorganism.

Strategi virion untuk menghindari pertahanan imunitas host tidak membentuk antibodi (nonimmunogenik agent).

The protein is found predominantly in neurons, particularly at synapses in cholesterol-rich microdomains or

caveolae.

PrP is also expressed widely in cells of the immune system.

Normal cellular function of PrP:

1. Play a central role in neuronal signaling events.

2. Plays a central role in pathogenesis of prion diseases.

Prions have not been classified in the same way as viruses, thus there are no families, genera, or species.

They first are identified by their host species, clinical disease, and their associated lesions and then characterized

further by their molecular and biological properties.

Their primary amino acid sequence mainly reflects the host from which they were isolated, but also registers

mutations that define inherited variants.

Full amino acid sequences of virtually all important prion variants have been determined in different susceptible

species and, as described below, naturally occurring amino acid substitutions are associated with relative

susceptibility and incubation time in sheep and cervids (deer, elk, and moose).

Certain biological properties are used to distinguish strains of prions:

1. Incubation period and mortality pattern.

2. Distribution and extent of spongiform lesions, prion protein (PrP) plaques and astrogliosis in brains.

3. Titer of infectivity in brains

… PRION

… PRION

Characteristics of prions:

1. They can reach very high titers in the brains of their hosts.

2. Size has been noted as small as 30 nm, but can be highly variable depending on the strain.

3. Very resistant to ultraviolet and γ-irradiation, having a very small radiation target size.

4. The polymerize after proteinase-K digestion, forming helically wound amyloid fibrils 410 nm in diameter, which

are visible by electron microscopy.

5. Evoke no detectable acquired immune response in their host.

6. The most infectious prion particles are 14-28 PrP molecules.

PRION (INFECTIOUS PROTEIN)

DISEASES CAUSED BY PRION

Scrapie of sheep and goats.

Bovine spongiform encephalopathy (which has occurred in cats and captive exotic felids and ungulates).

Transmissible mink encephalopathy (scrapie in mink).

Chronic wasting disease of mule deer and elk, kuru (human).

Creutzfeldt-Jakob disease (human), new variant Creutzfeldt-Jakob disease (human).

Gerstmann-Strussler-Scheinker syndrome (human).

Fatal familial insomnia (humans).

PR

ION

DISE

ASE

OF A

NIM

ALS

AN

D H

UM

AN

S

TRANSMISSION

Prions from animals and humans can also be transmitted to various other animals.

Scrapie among sheep and goats (unproved).

BSE consumption of feed supplements contaminated with tissues of infected animals.

Kuru contact with brain tissue of infected people during rites of ritualistic cannibalism.

Although the “species barrier” typically results in prolonged and highly variable incubation periods.

Makanan yang tercemar, plasenta induk, meat and bone meal.

PRION’S REPLICATION

MECHANISMS OF ACCUMULATION

OF PRPSC IN NEURONS

CLINICAL FEATURE

Incubation periode: 2-5 years.

Tremors head and neck (sudden noise/ movement), intense pruritus, wool loss and skin rubbed raw, emaciation,

weakness, weaving gait, staring eyes, ataxia, and hindquarter paralysis, die.

The clinical signs, prion plaque morphology and distribution in the brain, and biochemical properties can change

dramatically in a new species, indicating that a new conformational variant or “strain” has emerged.

Subsequent passage of the new prion within the same host typically leads to a decrease in the incubation period,

as prion conversion within the new host PrPC sequence becomes more efficient.

… CLINICAL FEATURE

PATHOGENESIS AND PATHOLOGY

Sporadic spongiform encephalopathy of older sheep and goats

Oral route or from superficial wounds in pastures contaminated by placental tissue or body fluids.

Transplacental or postpartum infection.

Experimental: peripheral routes of inoculation (intraperitoneal, subcutaneous, or intravenous) after prolonged

incubation periods,

Intracerebral shorter incubation period.

Occurs in the intestines, tonsils, spleen, and lymph nodes.

… PATHOGENESIS AND PATHOLOGY

The prion diseases are characterized by very long incubation periods, measured in

years.

Signs of prion disease include dementia and loss of coordination; the patient gradually

deteriorates, and death is inevitable.

The prion diseases are known as transmissible spongiform encephalopathies (TSEs):

1. encephalopathy means disease of the brain.

2. spongiform refers to the development of holes in the brain, making it appear like a

sponge.

3. transmissible refers to the fact that the causative agent is infectious. It can be

transmitted to members of the same species, and sometimes to other species.

… PATHOGENESIS AND PATHOLOGY

Sequential infectivity titrations of organs have suggested that following the ingestion of prions, infection is initiated

in gut lymphoid tissues and prions produced in these tissues then move to the central nervous system.

Lesions of the brain neuronal vacuolation, degeneration and astrocytic hypertrophy and hyperplasia.

There is no inflammatory reaction or evidence of an immune response.

Lesions and PrPSc accumulation occur in the cerebellum, rather than in the dorsal motor nucleus of the vagus

nerve in the medulla as occurs in classical scrapie.

PrPSc is apparently absent from lymphoid tissues.

MEC

HA

NISM

S IN T

HE PA

TH

OG

EN

ESIS

OF T

RA

NSM

ISSIBLE SP

ON

GIF

OR

M

EN

CEPH

ALO

PAT

HIE

S

NEURONAL CELL DEATH

1. An abnormal isoform of PrP is the infectious agent the most highly enriched preparations contain one

infectious unit per 10^5 PrP monomers.

2. Direct neurotoxic effects from a region of the PrP encompassing residues 106–126 to increased oxidative stress

in neurons as a result of PrPc depletion which has been proposed to function as an antioxidant molecule.

3. PrPc plays a role in regulating apoptosis with disturbance of normal cellular levels of PrP during infection leading

to cell death.

4. Prion neurodegeneration is related, at least in part, to loss of function of PrPc.

HIST

OPA

TH

OLO

GY

Spongiform

HISTOPATHOLOGY

Typical spongiform change in neurons Spongiform change and astrocytic

hypertrophy and hyperplasia

LAB DIAGNOSIS

Clinical signs, flock history, and histopathologic examination of the brain.

Anti-PrP antibodies immunohistochemical (suspect brain specimens)

Western blot assays of solubilized brain extracts and cerebrospinal fluid.

ELISA of solubilized brain extracts treated with proteinase K to digest PrPc.

Antemortem (generally useful only in sheep older than 6 months) biopsy sampling of lymphoid tissue from the

nictitating membrane, palatine tonsil, or rectal mucosa.

PREVENTION, CONTROL, THERAPY

Countries with enzootic scrapie may seek to eradicate the disease.

Larangan import hewan/ bahan pangan dari negara yang terdapat kasus Scrapie/ BSE.

Negara dibagi: negara bebas, zona bebas sementara, negara dengan insiden rendah, dan negara dengan insiden

tinggi.

Belum ada terapi/ vaksin.

ENZOOTIC

BOVINE

LEUKOSIS

drh. Sruti Listra Adrenalin, M.Sc.

30 Maret 2020

Retro

viru

s of

An

imals

Introduction

– First described in 1871, although the causative agent (bovine leukemia virus) was not identified and first characterized until 1969.

– Host: cattle (dairy cattle usually have the highest rates of infection), water buffalo. Experimentally: rabbits, rats, chickens, pigs, goats, and sheep.

– Bovine leukemia virus causes a persistent lifelong infection that can progress to multicentric lymphosarcoma (lymphoma) in a small subset of infected adult cattle.

– Bovine leukemia virus is the sporadic cause of solid lymphoid tumors in cattle and is generally not associated with leukemia.

– Bovine leukemia virus exhibits a distinct tropism for B lymphocytes, as their name implies, the primate viruses infect T lymphocytes.

… Introduction

– Bersifat persisten dan malignan.

– Lebih sering terjadi pada sapi perah dibandingkan sapi potong.

– Kerugian ekonomi:

1. Kematian sapi

2. Berkurangnya prod. susu

3. Biaya perawatan dan pengobatan meningkat

4. Biaya penggantian sapi/ culling

5. Afkir karkas.

Causes

– Famili Retroviridae, Genus Deltaretrovirus

– The deltaretroviruses also encode several unique accessory/regulatory proteins

including the Tax and Rex proteins.

– Tax (transactivating protein) enhances transcription of the viral promoter by

binding unique sites in the U3 region of the LTR (Tax response elements or TRE).

– The Rex protein facilitates the shuttling of singly spliced and unspliced viral RNA

from the nucleus into the cytoplasm, a function that is similar to that of the Rev

protein of lentiviruses.

Structure of

retrovirus

particles

Retroviruses

– Virions are enveloped, 80-100 nm in diameter, and have a three-layered

structure: an innermost genomenucleoprotein complex with helical symmetry,

surrounded by an icosahedral capsid, in turn surrounded by an envelope with

glycoprotein peplomers.

– The genome is diploid, consisting of a dimer of two molecules of linear positive-

sense, single-stranded RNA, each 7-11 kb in size. Genomic RNA has a 3'-

polyadenylated tail and a 5'-cap.

– All retroviruses have gag, pal, and env genes; some acquire an oncogene and

are usually defective in their own replication as a consequence; lentiviruses

have a complex array of up to six accessory genes.

… Retrovirus

– Viral reverse transcriptase transcribes DNA from virion RNA following the

formation of long terminal repeats; circular double-stranded DNA is formed and

integrates into cellular chromosomal DNA as a provirus.

– In productive infections, virions assemble at and bud from plasma membrane.

– Some retroviruses produce tumors, particularly leukemias and sarcomas;

members of the genus Lentivirus produce slow demyelinating neurologic

disease, arthritis, generalized chronic debilitating disease, or acquired

immunodeficiency syndromes.

Rep

licatio

n o

f

Retro

viru

s

Transmission

– Cell-to-cell contacts for its transmission between infected cells and uninfected target cells (so-called virologic synapse).

– Horizontally between cattle through contact with bodily fluids containing infected cells (blood and milk).

– The reuse of rectal examination gloves.

– Contaminated needles/surgical instruments,

– Fomites such as restraint devices, and biting insects that serve as mechanical vectors of the virus.

– From dam to offspring through the ingestion of infected milk as only some (

Clinical Features

– The majority of bovine leukemia virus infections of cattle are subclinical but can be detected by serologic assays.

– Approximately 30% of infected cattle eventually develop persistent lymphocytosis (persistently 7500 lymphocytes/ μL blood), which is usually not associated with any obvious clinical signs.

– Approximately 13% of infected animals develop multicentric lymphosarcoma by 48 years of age.

– The infection can result in economic losses from the culling of high-producing dairy cows because of reduced production and restrictions on exportation of cattle.

… Clinical Features

Generalized lymphadenopathy in lymphosarcoma

Enlarged external lymph nodes on a cow with Bovine Leukemia

Pathogenesis and Pathology

– The primary target cell of bovine leukemia virus infection is the B lymphocyte,

although monocytes and macrophages can also be infected.

– Cattle that develop lymphosarcoma of B-lymphocyte origin can have solid

tumors in a variety of organs (peripheral and central lymph nodes, heart,

spleen, kidney, abomasum, spinal meninges, brain, the retrobulbar region, and

uterus).

– Bovine leukemia virusinduced cell transformation is not the result of insertional

mutagenesis, rather the viral oncoprotein Tax promotes both cell survival

(through enhanced Bcl-2 expression) and cell proliferation.

… Pathogenesis and Pathology

– Viral gene expression is also regulated epigenetically through histone protein

modifications like acetylation and/or methylation, and these epigenetic

modifications help the virus to maintain transcriptional silence and thereby

persist in the face of a robust immune response (latency).

– Bovine leukemia virus infection can result in abnormal immune function,

leading to immunosuppression of infected cattle and enhanced susceptibly to

other infectious diseases.

… Pathogenesis and Pathology

– Masa inkubasi 1,5-2 th.

– Sering terjadi pada sapi umur 4-8 th (jrang

Path

olg

y

Lymphosarcoma(lymphoma) in a bovine heart.Extensive neoplastic involvement (arrows) of the epicardialsurface.

BLV induced tumors

on the heart of a cow.

Tumors from BLV

are commonly found

in the uterus,

abomasum, heart

and external lymph

nodes.

Diagnosis

– Virus-specific antibodies can be detected within the first few weeks and tend to

persist for life.

– Both the viral envelope (gp51) and Gag (p24 capsid) proteins elicit particularly

strong humoral responses, and antibodies to the viral Tax protein have also

been detected.

– Serologic assays used to detect virus-specific antibodies include ELISA, agar gel

immunodiffusion, and syncytium-inhibition assays.

– PCR assays are used to detect viral nucleic acid.

… Diagnosis

– Isolasi virus:

1. Sel monolayer:

limpa embrionik sapi sinsitium (4-6 hari)

diploid embrionik manusia sinsitium (6-8 hari)

2. Cell line:

limpa fetal sapi/ paru-paru sapi muda/ ginjal domba muda CPE

Dif. diagnosis

1. Limfadenitis

2. Limfoid hyperplasia

3. Hyperplastik haemolymph node

4. Pericarditis

5. Enlarged spleen in septicemic cond.

6. Neoplasma dan infeksi parasit

Prevention and Control

– “test and cull” strategies.

– Testing at 23 month intervals with positive-testing cattle being removed

immediately.

– If the prevalence of infection is too high to permit removal of all seropositive

cattle, segregation of seropositive/seronegative cattle may be attempted.

– Calves from infected dams should be isolated, tested, and allowed to enter the

seronegative herd only if they remain seronegative at 6 months of age.

Infectious Bovine Rhinotracheitis (IBR)-Infectious Pustular Vulvovaginitis (IPV)drh. Sruti Listra Adrenalin, M.Sc.30 Maret 2020

Herp

esviruses in

An

imals

Herp

ervirus

in D

om

estic An

imals

Herpesviruses

Virions are enveloped and variably sized (approximately 200300 nm in diameter), containing an icosahedral nucleocapsid of approximately 125 nm composed of 162 capsomers.

Genome is linear double-stranded DNA, 108300 kbp in size.

Replication occurs in the nucleus, with sequential transcription and translation of immediate early (α), early (β), and late (γ) genes producing α, β, and γ proteins, respectively; the α proteins are mainly transcription factors regulating expression of β proteins involved in DNA replication and transcription and the structural γ proteins.

DNA replication and encapsidation occur in the nucleus; there are two envelopments. The primary enveloped is acquired by budding through the inner layer of the nuclear envelope, which is lost by fusion with the outer nuclear membrane. Final envelopment occurs at Golgi or endosomal vesicles.

Infection results in characteristic eosinophilic intranuclear inclusion bodies.

Infection becomes latent, with recrudescence and intermittent virus shedding.

Bovine Herpesvirus 1

Famili: Herpesviridae, Subfamili: Alphaherpesvirinae.

Diseases: rhinotracheitis, pustular vaginitis, balanoposthitis, conjunctivitis, abortion, enteritis, a generalized disease of newborn calves, and possibly encephalitis.

Structure of herpesvirusKet: G (genome), C (capsid), T (tegument), E (envelope)

Rep

lication

of H

erpesviru

s

Transmission

Horizontal: leleran hidung, mata, plasenta sapi abortus

Hewan sembuh dapat menjadi carrier.

IBR: Establish of latency (1st time) reactivation from latency replication in ephitelial cells infection of susceptible animal replication in ep. cells (rhinotracheitis) systemic cell-associated spread encephalitis, infection of the fetus (abortion).

IPV: vertical koitus; Horizontal jarang terjadi.

Clinical Features (Infectious Pustular Vulvovaginitis )

Recognized most commonly in dairy cows.

Fever, depression, anorexia, and stand apart, often with the tail held away from contact with the vulva; micturition is frequent and painful.

The vulval labia are swollen, there is a slight vulval discharge, and the vestibular mucosa is reddened with many small pustules.

Adjacent pustules usually coalesce to form a fibrinous pseudomembrane that covers an ulcerated mucosa. The acute stage of the disease lasts 4-5 days and uncomplicated lesions usually heal by 10 to 14 days. Many cases are subclinical or go unnoticed.

Cattle, female. Moderate hyperemia and lightly red granulate lesion in the ventral area of the vulvar mucosa

Infectious Bovine Rhinotracheitis

Subclinical, mild, or severe disease.

Morbidity 100%, mortality 10%.

Fever, depression, inappetence, and a profuse nasal discharge, initially serous and later mucopurulent.

The nasal mucosa is hyperemic and lesions within the nasal cavity, which may be difficult to see, progress from focal pustular necrosis to large areas of shallow, hemorrhagic, ulcerated mucosa covered by a cream-colored diphtheritic membrane. The breath may be fetid. Dyspnea, mouth breathing, salivation, and a deep bronchial cough are common. Acute, uncomplicated cases last 5-10 days.

… IBR

Common clinical sign in cattle, unilateral or bilateral conjunctivitis, often with profuse lacrimation, but may occur in a herd as an almost exclusive clinical sign.

Gastroenteritis may occur in adult cattle and is a prominent finding in the generalized disease of neonatal calves, which is often fatal. Abortion may occur at 4-7 months gestation, and the virus has also been reported to be cause mastitis.

… IBR

Purulent nasal discharge

Pathogenesis and Pathology

Genital disease may result from coitus or artificial insemination, although some outbreaks, particularly in dairy cows, may occur in the absence of coitus.

Respiratory disease and conjunctivitis result from droplet transmission. Within the animal, dissemination of the virus from the initial focus of infection probably occurs via a cellassociated viremia.

Lifelong latent infection with periodic virus shedding occurs after bovine herpesvirus 1 infection; the sciatic and trigeminal ganglia are the sites of latency following genital and respiratory disease, respectively.

The administration of corticosteroids results in reactivation of the virus and has been used as a means of detecting and eliminating carrier bulls in artificial insemination centers.

… Pathogenesis and Pathology

Genital and the respiratory forms of the disease the lesions are focal areas of epithelial cell necrosis in which there is ballooning of epithelial cells; typical herpesvirus inclusions may be present in nuclei at the periphery of necrotic foci.

There is an intense inflammatory response. Gross lesions are not observed in aborted fetuses, but microscopic necrotic foci are present in most tissues and the liver is affected consistently.

Gross Pathology

Thick plaques of fibrinonecrotic exudate cover the nasal (right arrow), pharyngeal (left arrow), laryngeal, and tracheal mucosae Severe tracheitis

Lab. Diagnosis

Electron microscopy of vesicular fluid or scrapings and immunofluorescence staining of smears or tissue sections and detection of viral nucleic acid by the polymerase chain reaction.

Viral isolation and characterization cell cultures derived from their natural host.

Rapid cytopathic effect, with syncytia and characteristic eosinophilic intranuclearinclusion bodies.

Polymerase chain reaction for virus detection and specific enzyme immunoassays for antibody detection.

Dif. Diagnosis

IBR

1. Enzootic bronchopneumonia

2. BVD

3. Mucosal disease

4. Rinderpest

5. Bovine malignant catarrhal fever

6. Theileriosis

IPV

1. Trichomonas

2. Vibriosis

3. BVD/ MD

4. Brucellosis

5. Listeriosis

6. Leptospirosis

Prevention and Control

Vaksin rekombinan (menekan kejadian) imunitas terbentuk 10-14 harikemudian, bertahan beberapa tahun.

Hewan sembuh terbentuk kekebalan.

Kekebalan pasif melalui kolostrum.

References

Carter, J.B., Saunders, V.A. 2007. Virology Principles and Applications. John Wiley & Sons, Ltd.

MacLachlan, N.J., Dubovi, E.J. 2016. Fenner’s Veterinary Virology 5th Edition. Academic Press is an Imprint of Elsevier.

Mahy, B.W.J., van Regenmortel, M.H.V. 2010. Desk Encyclopedia of Animal and Bacterial Virology. Academic Press.

McVey, D.S., Kennedy, M., Chengappa, M.M. 2004. Veterinary Microbiology 3rd Edition. Wiley-Blackwell.

Murphy, F.A., Gibbs, E.P.J., Horzinek, M.C., Studdert, M.J. 1999. Veterinary Virology 3rd Edition. Academic Press.

Quinn, P.J., Markey, B.K., Carter, M.E., Donnelly, W.J., Leonard, F.C. 2001. Veterinary Microbiology and Microbial Disease. Blackwell Science.

Zuckerman, A.J., Banatvala, J.E., Schoub, B.D., Griffths, P.D., Mortimer, P. 2009. Principles and Practice of Clinical Virology 6th Edition. Wiley-Blackwell.