Pathomorphological, molecular and immunohistochemical studies on respiratory pathogens in ruminants with special reference to parainfluenza virus type 3
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Date
2023-07
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LUVAS Hisar
Abstract
The present study was conducted on 120 ruminant carcasses (53 buffaloes, 18 cattle, 15 sheep and 34 goats)
suspected for respiratory affections presented to the post mortem hall of Department of Veterinary Pathology, LUVAS,
Hisar. Age wise mortality was more in calves (up to 8 months of age) followed by adults (more than 8 months) in case of
buffaloes and cattle whereas, in case of sheep and goats, it was more in adults (more than 6 months) followed by young
ones (up to 6 months). Sex wise mortality was more in females as compared to males in buffaloes, sheep and goats.
However, in case of cattle, mortality was higher in males as compared to females. Samples comprising of lung, tracheal
swab and heart blood subjected for bacteriological isolation and further confirmation by VITEK 2 system revealed
bacterial growth in 61(50.83 %) cases (26 buffaloes, 11 cattle, 6 sheep and 18 goats). However, in 59 cases no bacterial
growth was obtained. From 61 cases, different types of bacterial species (21 from buffaloes, 13 from cattle, 08 from
sheep and 11 from goats) were identified, out of which Pasteurella multocida, Mannheimia haemolytica, Escherichia
coli, Klebsiella pneumoniae spp. Sphingomonas paucimobilis, Streptococcus spp. were major bacterial isolates. Major
gross lesions included hyperaemia in nasal turbinate, congestion and haemorrhages in trachea and hydrothorax. Lungs
revealed congestion, haemorrhages, consolidation, emphysema, fibrin deposition over pleura and multiple abscesses.
Vascular changes were observed in spleen and lung associated lymph nodes. Microscopic examination of nasal turbinate
revealed rhinitis, deciliation and desquamation and trachea showed vascular changes, tracheitis and desquamation of
epithelium. Different types of pneumonia diagnosed were serous pneumonia (5 buffaloes, 1 cattle, 5 sheep and 11 goats);
suppurative pneumonia (1 buffalo and 1 goat); fibrinous pneumonia (1 buffalo); serofibrinous pneumonia (8 buffaloes, 1
cattle, 2 sheep and 3 goats); interstitial pneumonia (10 buffaloes, 4 cattle, 1 sheep and 2 goats); sero-interstitial
pneumonia (4 buffaloes and 3 goats); sero-fibrinous interstitial pneumonia (2 buffaloes, 3 cattle and 4 sheep); serofibrinous bronchopneumonia (2 buffaloes, 4 cattle and 2 goats); suppurative bronchopneumonia (4 buffaloes, 2 cattle and
4 goats); serofibrinous pleuro-bronchopneumonia (1 buffalo); broncho-interstitial pneumonia (1 buffalo and 1 cattle);
pyogranulomatous pneumonia/mycotic pneumonia (1 buffalo); caseonecrotic bronchopneumonia (1 sheep). Pulmonary
adenomatosis was also diagnosed in a sheep. In buffaloes, interstitial pneumonia was most common whereas, in cattle,
interstitial pneumonia and serofibrinous bronchopneumonia were present in equal proportion. Serous pneumonia was the
most common affection in sheep and goats. Lung associated lymph nodes showed lymphadenitis, disruption of lymphoid
follicle; spleen revealed splenitis and depletion of lymphocytes. In lungs different types of pneumonia were evident. P.
multocida in lung samples was detected in 7.55 % (4/53) cases of buffaloes; 5.55 % (1/18) cases of cattle; 6.67 % (1/15)
cases of sheep and 5.88 % (2/34) cases of goats by conventional PCR targeting KMT1 gene. M. haemolytica in lung
samples was detected in 7.55 % (4/53) cases of buffaloes; 5.55 % (1/18) cases of cattle; 20 % (3/15) cases of sheep and
8.82 % (3/34) cases of goats by PCR targeting rpt2 gene. Virulence associated gene (lktC) of M. haemolytica in lung
samples was detected in 7.55 % (4/53) cases of buffaloes; 20 % (3/15) cases of sheep and 8.82 % (3/34) cases of goats.
BPI-3 was detected in 5.66 % (3/53) cases of buffaloes; 6.67 % (1/15) cases of sheep and 2.94 % (1/34) cases of goats by
targeting nucleocapsid gene. P. multocida antigen was detected in randomly selected lung tissues of 49 cases using
hyperimmune sera raised in mouse. The species wise immunopositive reaction for P. multocida included 63.15% (12/19)
in buffalo, 37.50 % (03/08) in cattle, 66.67 % (06/15) in sheep and 75 % (11/12) in goat cases. On comparison of
bacteriological, PCR and immunohistochemistry technique for the detection of P. multocida, immunohistochemistry was
found to be more sensitive followed by PCR and then culture method.