EIA

Question 1

Genome of EIAV rna virus

Answer 1

3 principal genes- gag, pol, env;
3 regulatory genes- viral replication &
pathogenesis

Question 2

Most consisitent finding in EIA.

Answer 2

• THROMBOCYTOPENIA- Earliest and most consistent feature of acute, febrile episodes due to deposition of virus-antibody complex on platelets which are subsequently removed by tissue macrophages.
• ANAEMIA- A consistent clinical abnormality - due toshortened life of RBC (from normal 130 days to anaemic 38 days) and decreased production. The reduced lifespan is due
  to phagocytosis of RBC containing virus-Ab complex on their surface.

Question 3

How are the symptoms formed in eia?

Answer 3

Major clinical signs and lesions are attributable to the
host response to virus and not direct viral damage to
tissue. The up regulation of proinflammatory cytokines like TNF-α, IL-1 and IL-6 as a result of infection of macrophages with EIAV also causes these symptoms characterisitic of the disease.The virus antibody complex is readily phagocytosed by reticuloendothelial system leading to development of clinical signs.

Question 4

p26

Answer 4

A major group specific antigen that is conserved
and forms the basis of AGID and c- ELISA diagnostic
tests of EIA

Question 5

Feeding habit of Vector

Answer 5

Painful bites, interrupted feeding, when feeding interrupted they will move to next host within 200m and transfer the blood about 10nL

Exception- Progeny of seropositive mare may receive
maternal antibody after suckling colostrum

Question 6

Pol gene

Answer 6

Pol gene- encodes enzymes required for viral replication (reverse transcriptase) and integration into the host cell genome (integrase)

Question 7

VERY IMPORTANT

sideroleucocytes

Answer 7

Clearance of RBC by reticulo-endothelial cells
is evidenced by presence of sideroleucocytes (leucocytes with hemosiderin pigment) in peripheral blood of infected horse. Sideroleucocytes or siderophytes (macrophages with hemosiderin) is highly suggestive of EIA

Question 8

Viral genome presence in body indicative of what?

Answer 8

The presence of viral RNA in blood is suggestive of viral replication. The presence of viral DNA in hos tissues is suggestive of infection

Question 9

Transmission of EIA

Answer 9

1. Vectors - Tabanus, Stomoxys, Chrysopus
2. Vertical transmission
3. Venerial transmission
4. Iatrogenic transmission

Only known source of infection is
antibody positive animals

Question 10

What are the major contributing factors for EIAV persistence ?

Answer 10

Antigenic variations and immune response

Question 11

Principal mechanism of EIAV
persistence within host

Answer 11

Incorporation of provirus into the host
genome

Question 12

QUASI

Antigenic shift and drift

Quasispecies

Answer 12

Viral envelope glycoprotein (gp45 & gp90) which are
present on the surface of virus is highly prone to
change i.e., Shifting antigenic configuration/Antigenic
drift- leading to emergence of novel antigenic strains within an individual horse with relapsing febrile
reactions.

variations in viral regulatory protein ‘Rev’ also cause viral variants

Question 13

Synonyms of EIA

Answer 13

1. Swamp fever
2. Mountain fever
3. Slow fever
4. Equine malarial fever
5. Coggin’s disease

Question 14

True or false

The horses become persistently
infected lifelong inapparent carriers in the case of EIAV

Answer 14

TRUE

Question 15

Hall mark
of chronic form of EIA

Answer 15

Edema on ventral abdomen,perpuce,legs

Question 16

env gene

Answer 16

Enocodes the viral envelope surface unit (gp
90) & transmembrane (gp45)glycoproteins

Question 17

Ethiology of EIA

Answer 17

Lentivirus of the family retroviridae

Question 18

The first animal disease to be assigned a viral etiology

Answer 18

EIA

Question 19

gag Gene

Answer 19

Encodes for the structural proteins needed
for the viral assembly and encapsidation of the genome.
Matrix
Nucleocapsid
Capsid eg: p26

Question 20

What is EIA?

Answer 20

Equine infectious anemia (EIA) is a persistent
infectious disease of horses and all other equids, caused by a macrophage tropic lentivirus, characterized by intermittent fever, anaemia, generalized lymphoproliferative changes, edema and weight loss (cachexia).

Mesenchymotrophic virus

Question 21

Pathogenesis of EIA

Answer 21

Primary entry

Infection of tissue macrophages esp. in spleen

Destruction of macrophages and release of virus and
its components

Production of Antibody to Antigenic components

Formation of Antigen-Antibody complex

Subsidence of pathological process as virus neutralizing antibodies forms

Restrains viral multiplication in macrophages

Appearance of a new antigenic variant of virus

Commencement of new cycle of viral replication in
macrophages and a new clinical episode

Less frequent recurrence of these episodes and horses become permanently asymptomatic

Question 23

Clinical signs of EIA

Answer 23

IP- 2-4 weeks
 Acute, Chronic or inapparent forms
 Anorexia, depression, profound weakness,
 Anaemia, tachycardia, tachypnea,
 Intermittent fever (upto 105 0F)
 Jaundice, epistaxis, pale MM, splenomegaly
 Petichal hemorrhage in mucosa esp. under tongue and
conjunctiva
 Abortion and chronic weight loss

Question 24

Diagnosis of EIA

Answer 24

• Clinical signs
• CBC- Anaemia,leukocytosis/leukopenia, monocytosis
• Elevated liver enzymes- hypergammaglobulunemia,hyperbilirubinemia
• PM Lesions= Necrotizing vasculitis, splenomegaly raspberry spleen,hepatomegaly, lymphadenopathy,ventral subcutaneous edema; vessel thrombosis;mucosal and visceral hemorrhage. On histopathology,
  non suppurative hepatitis, glomerulonephritis etc. Petechial hemorrhages under the tongue and anterior nares are pathognomonic of EIA in horses and Nutmeg
  appearance of liver

Question 25

Pathagnamonic signs of EIA in horses

Answer 25

Petechal hemorrhage in the conjuctiva, anterior nares and under the tongue.