African swine fever: A permanent threat to Indian pigs

India has 9 million pigs, of which 45% are in the North eastern (NE) states of India. Viral diseases affecting pigs are a major concern of mortality causing huge loss to the pig farmers. One such disease is African swine fever (ASF) that has already knocked the porous borders of NE states of India. ASF is a highly contagious devastating disease of pigs and wild boars causing 100% mortality. The causative agent African swine fever virus (ASFV) belongs to the genus Asfivirus, family Asfarviridae. Pig is the only species affected by this virus. Soft ticks (Ornithodoros genus) are shown to be reservoir and transmission vectors of ASFV. Transmission is very rapid and quickly engulfs the entire pig population. It is very difficult to differentiate classical swine fever from ASF since clinical symptoms overlap. Infected and in contact pigs should be culled immediately and buried deep, and sheds and premises be disinfected to control the disease. There is no vaccine available commercially. Since its first report in Kenya in 1921, the disease has been reported from the countries in Europe, Russian federation, China, and Myanmar. The disease is a threat to Indian pigs. OIE published the first report of ASF in India on May 21, 2020, wherein, a total of 3701 pigs died from 11 outbreaks (Morbidity - 38.45% and mortality - 33.89%) in Assam and Arunachal Pradesh states of India. ASF is non-zoonotic

Prevalence and antibiotic susceptibility of Mannheimia haemolytica and Pasteurella multocida isolated from ovine respiratory infection: A study from Karnataka, Southern India

Background and Aim: Respiratory infection due to Mannheimia haemolytica and Pasteurella multocida are responsible for huge economic losses in livestock sector globally and it is poorly understood in ovine population. The study aimed to investigate and characterize M. haemolytica and P. multocida from infected and healthy sheep to rule out the involvement of these bacteria in the disease. Materials and Methods: A total of 374 healthy and infected sheep samples were processed for isolation, direct detection by multiplex PCR (mPCR), and antibiotic susceptibility testing by phenotypic and genotypic methods. Results: Overall, 55 Pasteurella isolates (27 [7.2%] M. haemolytica and 28 [7.4%] P. multocida) were recovered and identified by bacteriological tests and species-specific PCR assays. Significant correlation between the detection of M. haemolytica (66.6%) with disease condition and P. multocida (19.1%) exclusively from infected sheep was recorded by mPCR. In vitro antibiotic susceptibility testing of 55 isolates revealed higher multidrug resistance in M. haemolytica (25.9%) than P. multocida (7.1%) isolates. Descending resistance towards penicillin (63.6%), oxytetracycline (23.6%), streptomycin (14.5%), and gentamicin (12.7%) and absolute sensitivity towards chloramphenicol were observed in both the pathogens. The antibiotic resistance genes such as strA (32.7%) and sul2 (32.7%) associated with streptomycin and sulfonamide resistance, respectively, were detected in the isolates. Conclusion: The study revealed the significant involvement of M. haemolytica together with P. multocida in ovine respiratory infection and is probably responsible for frequent disease outbreaks even after vaccination against hemorrhagic septicemia in sheep population of Karnataka, southern province of India

Development of recombinant sialidase (NanH) protein-based Indirect-ELISA for epidemiological survey of anti-Pasteurella multocida antibodies in bovines

697-704Haemorrhagic septicaemia (HS) is a highly contagious and fatal disease of cattle and buffaloes and causes major economic losses to farmers. Though indirect hemagglutination (IHA) test has been used to detect a specific antibody against P. multocida, it has low specificity for sero-diagnosis of HS. Therefore, development of a rapid, highly sensitive and specific serological test is a prerequisite for detection of antibodies against HS. In this context, we explored an in-house ELISA method using recombinant antigens for detection of antibodies against P. multocida in bovines. nanH gene from P. multocida B:2 strain P52 was cloned and the recombinant mature protein with a C- and N-terminal truncation was produced as a fusion protein (∼63 kDa) in Escherichia coli. The immunogenic potential of purified rNanH-Tr was assessed by the Western blot method using specific anti-rNanH-Tr antibody responses in sera collected from immunized rabbits. An indirect-ELISA based on rNanH-Tr was developed and optimized. Furthermore, the rNanH-Tr ELISA was applied to screen bovine serum samples (n=250). The receiver operating characteristic curve analysis for the detection of anti P. multocida specific antibodies indicated a diagnostic sensitivity of 86.2 (CI 73.26-96.80%) and specificity of 80.0 (63.06- 91.56%). No cross reactivity was noted with antibodies against other bovine diseases (e.g., foot-and-mouth disease and brucellosis). Screening of random bovine serum samples showed a 22% sero-positivity for anti P. multocida specific antibodies