Serological and molecular evidence of bluetongue in sheep and goats in Uttar Pradesh, India

Cross-sectional experimental study was conducted with the objective to estimate the seroprevalence on the basis of antibodies to VP7 protein of bluetongue virus by competitive enzyme linked immunosorbent assay (c-ELISA), to test the neutralizing ability of the antibody to reference strains of 4 BTV serotypes (BTV-1, 2, 10 and 23) by micro serum neutralization assay (m-SNT), to check the presence of BTV dsRNA and to isolate and characterize bluetongue virus (BTV). A total of 91 serum and 26 whole blood samples were obtained from sheep and goat. The study was conducted between September and November, 2012 when the culicoides midges’ activity is maximal. The animals were observed for clinical signs of BTV infection and serum samples were obtained from all animals for c-ELISA and m-SNT. Further, blood samples were collected from the c-ELISA positive animals and subjected to virus isolation and nested RT-PCR. Out of 91 animals tested, 26 (28.6%) were found to be seropositive by c-ELISA and one sheep showed neutralizing antibody against BTV-1 serotype at a titer of 1.2 log10. Multivalent logistic regression analysis of risk factors like age, sex, body condition and species of animals were considered during the serological study and found that species of animal had significant influence (χ2 = 17.111, P<0.05) in seropositivity of BTV. Goats showed more seropositivity to bluetongue as compared to sheep (OR = 0.233). Other risk factors had no significant influence (P>0.05) on seropositivity. It was worth enough to conclude that higher seroprevalence among goats indicated that goats would be the most important animals in the epidemiology of BTV with less clinical manifestation due to development of acquired immunity as the result of continuous exposure.Keywords: Bluetongue virus (BTV), competitive enzyme linked immunosorbent assay (c-ELISA), goat, seroprevalence, sheep, micro serum neutralization assay (m-SNT), nested reverse transcription polymerase chain reaction (RT-PCR)African Journal of Biotechnology Vol. 12(19), pp. 2699-270

HISTOPATHOLOGICAL AND IMMUNO-HISTOCHEMICAL EVALUATION OF MALE AND FEMALE REPRODUCTIVE SYSTEMS OF PORCINE CIRCOVIRUS-2 INFECTED PIGS

Porcine Circovirus-2 (PCV-2) is an emerging swine infection responsible for significant financial losses in the global swine industry. It has a significant negative impact on reproductive performance causing abortion, stillbirth, and other anomalies. As there is limited knowledge related to the histopathology of male and female reproductive systems in PCV-2 infected pigs, the current study was designed. Swine carcasses presented for post-mortem examination with a history of respiratory distress, anorexia, diarrhoea, wasting, and paleness of the skin collected from mid of 2021 to mid of 2022 from different parts of Kerala, India, were utilised in this study. The samples were initially screened with polymerase chain reaction (PCR) and were subjected to gross and histopathological studies. Out of 65 collected samples, 10 were positive for PCV-2 by PCR. The positive sample carcasses were emaciated, had poor body condition with visible bony prominences, decreased back fat thickness, rough, long hair coat, and sunken eyes. Mild oedema and congestion were seen in the testes, epididymis, and vas deferens of the male reproductive system and on accessory reproductive glands such as the bulbourethral gland, prostate gland, and seminal vesicle. In the female reproductive system, the ovary, oviduct, and uterus had mild congestion and oedema in most cases. Histopathology of the male reproductive system revealed mild degenerative changes, haemorrhage, and congestion in all cases. The vasa deferentia showed a loss of cilia in the pseudostratified columnar epithelium. The female reproductive organs had congestion, degenerative changes, and infiltration of mononuclear cells. For further confirmation, localisation of PCV-2 antigen was done in reproductive organs with immunohistochemistry (IHC). History, gross, histopathological findings, and PCR in combination with IHC highlight the pathologic effects of PCV-2 on reproductive organs in infected pigs

MOLECULAR PREVALENCE OF PORCINE CIRCOVIRUS 2 INFECTION: FOREMOST REPORT IN SOUTHERN STATES OF INDIA

Porcine circovirus 2 (PCV2) is the emerging viral pathogen in the swine associated with multi-systemic clinical and subclinical outcomes. This study aimed to detect the molecular and serological prevalence of PCV2 infection in the southern states of India. A total of 434 random samples comprising serum (n=273), pooled postmortem tissues (n=109) and rectal, vaginal, and nasal swabs (n=52) and were collected from PCV2 suspected and healthy swine populations of Tamil Nadu, Kerala, Andhra Pradesh, Telangana, and Puducherry states in India from 2019 to 2021 were screened for PCV2 by specific polymerase chain reaction (PCR) assay. Of 434 samples screened, 12.2% (n=53) showed positivity to PCV2 genome. Statistical analysis of the molecular prevalence of PCV2 within breed, age, sex, and vaccination status revealed no significant (p>0.05) difference but there was a significant (p<0.05) difference in the prevalence of PCV2 among healthy and suspected swine populations. Suspected pigs had a significantly higher prevalence of PCV2 in comparison to healthy. ELISA-based PCV2 antibody screening in 176 non-vaccinated serum samples revealed a seropositivity of 44.8% (n=79). The molecular and seroprevalence of PCV2 is alarming in southern states of India, which necessitates the need for genotypic characterization and phylogenetic analysis and development of candidate vaccine for implementation of suitable prevention and control measures

Concurrent testing of breeding bulls for bovine herpesvirus 1 infection (BHV-1) in India

In this study, sera from 65 breeding and 19 training bulls from Uttar Pradesh State in north India were tested for bovine herpesvirus 1 (BHV-1) antibodies by enzyme linked immunosorbent assay (ELISA) and virus neutralization test (VNT). The VNT test could detect 56 (86.15%) and 9 (47.37%) of the samples from breeding and training bulls as positive for BHV-1 antibodies whereas in ELISA 63 (96.92%) and 10 (52.63%) were found positive, respectively. Semen samples from the breeding bulls were simultaneously tested by the Taqman based real time PCR (qPCR). Of the 65 samples screened, only 40 (61.54%) were found to contain BHV-1 DNA indicating that all the seropositive bulls are not shedding the virus in semen. When the RT-PCR positive samples were subjected to virus isolation on Madin-Darby bovine kidney (MDBK) cells, no virus isolates could be obtained. The advantages of concomitant testing of serum and semen of breeding bulls and measures for control of BHV-1 infections in bull farms are discussed

Detection of Newcastle disease virus and assessment of associated relative risk in backyard and commercial poultry in Kerala, India

Abstract Background Newcastle disease (ND) is an economically important viral disease affecting the poultry industry. In Kerala, a state in South India, incidences of ND in commercial and backyard poultry have been reported. But a systematic statewide study on the prevalence of the disease has not been carried out. Objectives A cross‐sectional survey was performed to detect the presence of Newcastle disease virus (NDV) in suspect cases and among apparently healthy commercial flocks and backyard poultry, in the state and to identify risk factors for NDV infection. Methods Real‐time reverse transcription‐PCR (RT‐PCR) was used to detect the M gene of NDV in choanal swabs and tissue samples collected from live and dead birds, respectively and the results were statistically analysed. Results The predominant clinical signs of the examined birds included mild respiratory signs, huddling together and greenish diarrhoea. Nervous signs in the form of torticollis were noticed in birds in some of the affected flocks. On necropsy, many birds had haemorrhages in the proventriculus and caecal tonsils which were suggestive of ND. Of the 2079 samples tested, 167 (8.0%) were positive for the NDV M‐gene by RT‐PCR. Among 893 samples collected from diseased flocks, 129 (14.5%), were positive for M gene with pairwise relative risk (RR) of 15.6 as compared to apparently healthy flocks where 6 out of 650 (0.9%) samples were positive. All positive samples were from poultry; none of the ducks, pigeons, turkey and wild birds were positive. Commercial broilers were at higher risk of infection than commercial layers (RR: 4.5) and backyard poultry (RR: 4.9). Similarly, birds reared under intensive housing conditions were at a higher risk of being infected as compared to those reared under semi‐intensive (RR: 6.7) or backyard housing (RR: 2.1). Multivariable analysis indicated that significantly higher risk of infection exists during migratory season and during ND outbreaks occurring nearby. Further, lower risk was observed with flock vaccination and backyard or semi‐intensive housing when compared to intensive housing. When the M gene positive samples were tested by RT‐PCR to determine whether the detected NDV were mesogenic/velogenic, 7 (4.2%) were positive. Conclusions In Kerala, NDV is endemic in poultry with birds reared commercially under intensive rearing systems being affected the most. The outcome of this study also provides a link between epidemiologic knowledge and the development of successful disease control measures. Statistical analysis suggests that wild bird migration season and presence of migratory birds influences the prevalence of the virus in the State. Further studies are needed to genotype and sub‐genotype the detected viruses and to generate baseline data on the prevalence of NDV strains, design better detection strategies, and determine patterns of NDV transmission across domestic poultry and wild bird populations in Kerala