SEROEPIDEMIOLOGY AND DETECTION OF PESTE DES PETITS RUMINANTS VIRUS IN SHEEP AND GOATS OF SAURASHTRA REGION OF GUJARAT 3264
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Date
2021-07
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JAU JUNAGADH
Abstract
Peste des petits ruminants (PPR) is a severe viral disease of goats and sheep with high morbidity and high mortality characterized by fever, erosive stomatitis, conjunctivitis, gastroenteritis and pneumonia. PPR is caused by Peste des petits ruminants virus (PPRV), a Paramyxovirus of the Morbilivirus genus. The virus continues to be reported periodically across India and Gujarat state. The present study was aimed to conduct overall, locationwise, specieswise , sexwise and agewise as well as pre & post vaccination seroprevalence survey by using c-ELISA and to detect PPRV in clinical samples using S-ELISA, N & F gene based RT-PCR and cell culture method from clinical samples.
A total of 828 (Prevaccinated ) & 423 (Postvaccinated) serum samples from sheep and goats of Jamnagar, Rajkot, Surendranagar, Amreli and Bhavnagar districts of Saurashtra region of Gujarat were screened for PPR specific antibodies using PPR specific c-ELISA. Overall percent seroprevalence of PPR was found to be 53.86% (446 / 828) & 72.34 % (306 / 423) in prevaccinated & post vaccinated small ruminants respectively . Overall percent prevaccinated/ post vaccinated seroprevalance rates were highest in Bhavnagar district (83.89% / 96.30%), followed by Surendranagar (73.61% / 77.78%), Amreli (56.25% / 83.33%) , Jamnagar (32.22% / 43.33 %) and Rajkot (27.78% / 64.44 %) districts. Pre & Post vaccination seropositivity was noted higher
in goats (59.90% / 78.75%) than (35.75% / 52.43 %) in sheep. Males showed higher seroprevalence (60.11% / 89.01%) as compared to their female counterparts (52.09% / 67.77 %).Higher Prevaccinated seroprevalence (63.41%) was recorded among age group of 1 to 2 years, followed by below 1 year age group (53.99%) and above 2 years of age group (44.20%).
A total of 119 different clinical samples (nasal swab, conjunctival swabs, oral swabs and tissue samples) from goat and sheep were collected from the area under study for detection of PPR antigen by Sandwich-ELISA. Out of 119 clinical samples, 37 samples were found positive in small ruminants by S-ELISA, giving an overall incidence rate of 31.09 % (37/119). In goats, 30.52 % and sheep 33.33 % samples were detected positive. District wise incidence of PPRV in small ruminants differed non significantly. It was recorded in Bhavnagar (33.90%), Amreli (29.41%) and Rajkot (26.92%) districts. Month wise incidence of PPRV in small ruminants differed non significantly. It was recorded in month of October (29.41%), November (31.58%) and December (33.33%). Age wise incidence of PPRV in small ruminants differed non significantly. It was recorded in below 1 year of age group (39.29%), 1 to 2 year (28.95%) and above 2 years of age (16.00%). Sex wise incidence of PPRV in small ruminants differed non significantly. It was recorded in male (30.43%) and female (31.51%).Breed wise incidence of PPRV in small ruminants differed non significantly. It was recorded (36.62%) in non descript breed and (22.92%) in descript breed.
Out of 119 clinical samples, 37 samples including 13 Nasal swabs, 3 conjunctival swabs, 7 oral swabs and 14 tissue were found positive. PPRV antigen was detected by S-ELISA in tissue (66.67%), oral swab (43.75%), nasal swab (20.97%) and conjunctival swab (15.00%). Most suitable sample for virus isolation was tissue and oral sample. 37 representative clinical samples positive for PPRV by S-ELISA were subjected for isolation and propagation of PPR virus in vero cells. Out of 37 S-ELISA positive samples, 31 samples showed CPE on first passage of sample, which was confirmed by RT-PCR.
One hundred nineteen clinical samples (40 nasal swabs, 20 conjunctival swabs, 16 oral swabs, and 9 lung, 4 trachea, 3 spleen, 3 intestine tissues from goat along with 22 nasal swabs and 1 lung, 1 intestine tissues of sheep) were tested by N gene & F gene based primers. Out of 119 samples, 35 samples produced 351 bp
amplicon with N gene primer and 32 samples produced 372 bp amplicon with F gene primer.
Out of the total samples tested PPRV could be detected in 37, 35 and 32 samples by S-ELISA, N gene RT-PCR and F gene RT-PCR respectively. Thirty one samples were positive to all four tests. Two samples negative by N gene RT-PCR were found positive by S-ELISA. Relative to S-ELISA, sensitivity and specificity of N gene based RT-PCR was 94.59 and 100 percent respectively. Overall agreement between the two tests was 98.32 percent. Relative to S-ELISA, sensitivity and specificity of F-gene based RT-PCR was 86.49% and 100% respectively. Overall agreement between the two test was 95.80% . Relative to S-ELISA sensitivity of cell culture was 83.78%.
All three PPRV sequence obtained from Bhavnagar, Amreli, Rajkot were belonged to lineage IV (Indian strains). All three PPRV sequence showed 100 % genetic identity with eachother & 98-99 % genetic identity with PPRV strain of Mehsana (North Gujarat), Bhopal (Madhayapradesh), Pune (Maharashtra), Jhansi (Uttarpradesh), Sungri (vaccine strain) based on partial N gene sequence.