study of the correlation between pathogenicity and strain of
bovine viral diarrhoea muuosal dise3ase bvd-md virus based on
the geneticaal divversisiya and clical symptoms
‫دراسة االرتباط بيى امراضية وعترة فيروس مرض االسهال الفيروس البقرى على اساسى االختالفات‬
‫الجينيه واالعراضى االكلينيكيه‬
usama abd el-hakem aly mostafa
‫أسامة عبدالحكيم على مصطفى‬
taha a.a el allawy, emad kamel nafee, laila s. ahmed
‫ ليلى صالح الدين أحمد‬،‫ عماد كامل نافعى‬،‫طه أحمد أحمد العالوى‬
Abstract:
SUMMARY
In this study three hundred (300) cattle with age ranged from one week to five were examined
using RT-PCR for detection of BVD viral RNA as a recent
hod for diagnosis of BVDV infections. According to their ages, these animals were ..ied into
three age groups, Group (1) included calves less than six months ,Group (2) included animals
with age ranged from six monthes to two years while oup (3) included animals with age ranged
from two to five years old. Fourty two
from Group (1) were examined out of them eight (8) animals (19%) were ive,two hundred and
nine (209) animals from Group (2) were examined out of eighty four (84) animals (40.2%) were
positive while fourty nine (49) animals from
(3) were examined out of them six (6) animals (12.2%) were positive.
By using proper combination of selected four primers (Fl ,R1 ,HCF1 and HCRI)
strains of BVDV were detected , these strains were Oregon (13.3%), T-20 (12.3%) KS86-1(÷)
(17.3%), KS86-2 (-) (22.4%) and No.12 (34.7%).These strains were ‘g two biotypes, CP (42.9%) and
NCP (57.1%), three strains (Oregon,T-20 and J-1 +) were cytopathic while the other two strains
were Non cytopathic (KS86-2No.12).
In order to study the correlation between the strain of BVDV and clinical ns,thirty animals were
used for clinical and haematological studies, these animals
classified into five groups according to the strain of BVDV. Anima’s infected with strain showed
Fever continued six days,nasal discharge continued thirteen
s,diarrhea continued fifteen days, lameness continued twenty one days, oral ris continued
eighteen days,salivation continued twenty days and leukopenia
tinued eight days.
infected with T-20 showed diarrhea continued three days and leukopenia intinued two days.
infected with KS86-1 (+) showed fever continued two days and leukopenia inued three
days.Animals infected with KS86-2 (-) showed fever continued three
days, nasal discharge continued seven days,diarrhea continued nine days, oral erosions
continued thirteen days,sallvation continued nineteen days, conjunctival discharge continued
fourteen days,pneumonia continued eleven days,leukopenia continued twelve days and
thrombocytopenia continued five days.Animals infected with No.12 strain suffered only from
leukopenia that continued ten days.
Microscopic examination revealed slight enteritis in all infected cattle except animals infected
with KS86-2(-) which exhibited severe hemorrhagic enteritis.All infected animals showed
depletion of thymus and alteration of lymphoid cell, this alteration was more pronounced at
peyer’s patches of small intestine and lymphoid nodules of large intestine,
Monoclonal-based immunohistochemical using Avidine-Biotin Complex (ABC) peroxidase
method was performed in order to study the distribution of BVD viral antigen in different
tissues collected from dead or culled thirty animals used in clinical and haematological
examination.The same technique was performed also to study the effect of BVDV infection on
the local immunity of intestine through detection the changes occured in four classes of
immunoglobulins (lgA,lgG, Secretory IgA and 1gM). Tissues collected for study the distribution
of BVD viral antigen were skin ,thymus, tonsil,parotid gland,submaxillàry gland,adrenal gland,
eosophagus, rumen, omasum, abomasum, pancreas small intestine, large intestine, uterus ,
cervix and mammry gland while tissues collected for the study of effect of BVDV on
immunologic status of the intestine were duodenum;,jejunum containing peyer’s patches
,ileum, lymphoid patches at ileocecal entrance,colon and rectum. Immunohistochemical study
revealed presence of BVD viral antigen in all examined tisssues. Sever reduction of
lgA,lgG,Secretory IgA and 1gM was reported in this study while the same effect did not proven
in infected calves less than two months age.
The results of our study revealed that:
-RT-PCR assay is rapid and sensitive technique can used for diagnosis and typing of BVDV.This
technique is very useful in screening of large number of animals and in case of presence of very
low number of virus infections that could not detected by conventional available methods.
Therefore, this assay must replace the conventional diagnostic methods that need long time,
lack high sensitivity and has another disadvantage.
th Cp and NCP strains of BVDV are pathogenic for cattle.
ection with NCP biotype were more prevalent than infection with CP.However, imals of age
Group (3) were infected with CP biotype (66.7%) more than Ncp type (33.3%).
e highest incidence of infection was observed in animals of age Group (2).
fly animals showed very mild clinical signs that could passed without tection.Therefore,
laboratory diagnosis of BVDV is very important.
biinicai signs observed with different BVDV strains were differ. Relation between age and
clinical signs did not observed.
o great differences were observed among different BVDV strains in gross and icroscopic post
mortem examination.Therefore, pathological examination can not fferentiat between different
BVDV strains.
onoclonal based immunohistochemical technique using ABC peroxidase method is
3pid,sensitive and have many advantages including its ability to correlat between resence of
BVDV antigen and pathological changes,this technique can be used when btaining of internal
samples are difficult for any reason, in these cases we can detect 3VDV in the skin.
Correlation between presence of BVDV antigen and pathological changes was
N rences in distribution of antigen among different BVDV strains were observed.
cause severe impairment of intestinal immunity through reduction of IgA,
g( 11secretory IgA and lgM,this effect did not proven in calves less than two months
= from the previously mentioned results we can record that RT-PCR have many dvantages over
the conventional diagnostic methods,therefore, this assay must dded to the conventional
diagnostic methods that need long time, lack high sensitivity nd has another disadvantage, so,
RT-PCR should have the periority in diagnosis of BVDV .Also immunohistochemical technique is
sensitive and rapid assay and must play a role as a tool for diagnosis of BVD either in anti and
post mortem examination.The correlation between BVDV strains and clinical outcome which
reflect the pathogenicity was proven.The role of BVDV as immunosuppressive agent was proven
through its effect on local immunity of the intestinal tract.