Short communication: Seroprevalence of paratuberculosis in Italian water buffaloes (Bubalus bubalis) in the region of Campania

Paratuberculosis is a chronic enteric disease affecting virtually all ruminants, but only anecdotal information is currently available about the occurrence of this disease in water buffaloes (Bubalus bubalis). We carried out a survey study aimed at determining the prevalence of paratuberculosis in 2 provinces in the region of Campania, Italy, where about half of all Italian buffaloes are reared. From May 2017 to December 2018, we collected 201,175 individual serum samples from 995 buffalo herds. The sera were collected from animals over 24 mo old and were tested using a commercial ELISA test. The herd-level apparent prevalence result was 54.7%, and the animal-level apparent prevalence was 1.8%. The herd-level true prevalence was estimated using a Bayesian approach, demonstrating a high herd-level prevalence of paratuberculosis in water buffaloes from the Campania area. These findings suggest that the urgent adoption of paratuberculosis herd-control programs for water buffaloes in this area would be beneficial.

Prevalence of antibodies against Bubaline herpesvirus (BuHV-1) among Mediterranean water buffalo (Bubalus bubalis) with implications in buffalo trade

BACKGROUND

Both Bovine herpesvirus (BoHV-1) and Bubaline herpesvirus (BuHV-1) have been reported to cross the species barrier. Antibody seroconversion in glycoprotein E (gE) blocking ELISA during BuHV-1 infection has been documented. Recent diagnostic efforts have focused on the development and application of discriminatory tests to distinguish between infections with BoHV-1 and BuHV-1.

OBJECTIVE

To evaluate the impact and distribution of these two infections in water buffalo farms in two regions (Piedmont (n = 3) and Campania (n = 10), Italy) where infectious bovine rhinotracheitis control programs have been implemented.

ANIMALS AND METHODS

Sampling was carried out on 13 buffalo farms comprising 1089 animals using specific gE-indirect ELISA's test able to discriminate among BoHV-1 and BuHV-1 infections.

RESULTS

59.0% of animals reacted positive to ELISA (irrespective of whether BoHV-1 or BuHV-1 antigen was used) and 86.4% of these were reactive to BuHV-1 only, whereas 11.8% showed absorbance values for both antigens and were classified as inconclusive. There was a statistically significant age-related difference in BuHV-1 infection rates but not in overall individual (47% vs. 58%) or herd prevalence (100% vs. 90%) of infection between the two regions.

CONCLUSION

The low percentage of sera reactive to BoHV-1 (1.8%, 12/643) indicates that BuHV-1 may be the main circulating alphaherpesvirus infection in Mediterranean water buffalo in the two study areas. Since Bubalus bubalis is included in Directive 64/432/EEC on animal health problems affecting intra-community trade in bovine animals, diagnostic testing with nonspecific ELISA for BoHV-1 infection in buffalo may yield false-positive reactions. This scenario could lead to economic losses and hamper buffalo trade and movement, particularly for reproduction purposes.

Expression and antigenic characterization of bubaline herpesvirus 1 (BuHV1) glycoprotein E and its potential application in the epidemiology and control of alphaherpesvirus infections in Mediterranean water buffalo

Bubaline herpesvirus 1 (BuHV1) is a member of ruminant alphaherpesviruses antigenically related to bovine herpesvirus 1 (BoHV1). The impact of BuHV1 infection in infectious bovine rhinotracheitis control program is difficult to establish, due to the lack of specific diagnostic test. The ectodomain of glycoprotein E of BuHV1 was expressed as recombinant secreted protein and used in indirect ELISA as well as in a discriminatory test using the BoHV1 counterpart. A panel of monoclonal antibodies was produced against BuHV1; 6 out of 7 anti-gE monoclonal antibodies specifically recognized the BuHV1 gE. Results indicated BuHV1 gE as a sensitive marker of infection compared to seroneutralization (SN) test or blocking ELISA. When BoHV1 and BuHV1 gEs were immobilized in different wells of the same ELISA microplate, bovine and water buffalo sera were more reactive against the respective infecting virus. About one third of seropositive buffaloes with no history of contact with cattle and having higher SN titres, reacted in BoHV1 gE blocking ELISA, possibly because of steric hindrance. Since in two occasions BuHV1 was also isolated from water buffalo scoring gB+/gE+ BoHV1 blocking ELISA, we conclude that the combination of the two blocking ELISAs is not suitable to differentiate between BoHV1 and BuHV1.

144 INFLUENCE OF REPEATED OVUM PICKUP ON BUFFALO WELFARE

The aim of this work was to evaluate the effect of repeated ovum pickup (OPU) on buffalo welfare. The OPU was carried out as previously described (Neglia et al. 2003 Theriogenology 59, 1123–1130) twice per week on 11 buffalo cows at 121 ± 15 days in milk for 2 months (end of October–end of December). Blood samples were collected before the beginning of the trial (time 0), after 1 month (time 1), and after 2 months (time 2) in animals that had undergone OPU and in control animals (n = 10) of the same herd. The following parameters of clinical immunology were evaluated on sera: haemolytic complement (Arya et al. 1992 Vet. Immunol. Immunopathol. 30, 411–418), lysozyme, bactericidal capacity (Amadori et al. 1997 J. Vet. Med. 44, 321–327), and haptoglobin (Phase Haptoglobin Colourimetric Assay kit, Tridelta Development Ltd., Maynooth, County Kildare, Ireland). Data, here reported as means ± s.e.m., were analysed by ANOVA taking into account treatment, time, and the interaction. The number of aspirated follicles and collected oocytes per buffalo per session was 6.6 ± 0.2 and 3.6 ± 0.2, respectively. Interestingly, the OPU treatment did not affect haptoglobin (a reliable marker of acute stress), lysozyme, complement, and bactericidal capacity, whereas the time influenced (P < 0.05) only the complement. In animals that had undergone OPU, no differences among times 0, 1, and 2 in lysozyme (3.9 ± 0.3, 4.0 ± 0.6, and 3.6 ± 0.4 μg mL–1, respectively), bactericidal capacity (92.8 ± 0.8, 92.1 ± 0.8, and 92.2 ± 0.9%, respectively), and haptoglobin (1.8 ± 0.4, 1.4 ± 0.2, and 1.9 ± 0.6 mg mL–1, respectively) were found. Likewise, similar values were recorded at times 0, 1, and 2 in the control group in lysozyme (3.2 ± 0.3, 2.9 ± 0.3, and 3.1 ± 0.8 μg mL–1, respectively), bactericidal capacity (94.2 ± 0.6, 93.0 ± 1.1, and 89.2 ± 3.2%, respectively), and haptoglobin (0.7 ± 0.5, 1.3 ± 0.5, and 1.4 ± 0.4 mg mL–1, respectively). A significant decrease (P < 0.05) of complement (UE/150 mL) in OPU-treated animals was recorded at times 1 (33.6 ± 1.4) and 2 (35.9 ± 2.9) compared to time 0 (67.3 ± 3.3). However, the same pattern was observed in the control (62.8 ± 4.0, 31.3 ± 0.3, and 31.0 ± 0.8, respectively at times 0, 1, and 2; P < 0.05). Therefore, it is not possible to rule out that the decrease was due to other factors, such as the cold winter temperatures incoming, as previously reported. Furthermore, the values recorded at times 1 and 2 fall in the physiological ranges of the species (De Carlo et al. 2011 Joint Annual Meeting, Riccione, Italy). During the whole period of the experiment (and few weeks after), there were neither signs of behavioural modifications nor clinical signs of any disease. Furthermore, there were no differences in average daily milk production between treated and control buffaloes both at the start (9.1 ± 0.8 v. 9.4 ± 0.8) and at the end of the trial (7.6 ± 0.6 v. 6.5 ± 0.7), and all the animals that had undergone OPU conceived within 113.0 ± 25.4 days from the last OPU session. These preliminary results indicate that a regimen of OPU carried out twice per week for 2 months do not affect the welfare of buffaloes.