Development of a novel one-step triplex PCR assay for the simultaneous detection of porcine circovirus type 2, porcine parvovirus and classical swine fever virus in a single tube.

Co-infection of multiple pathogens complicates diagnosis, treatment and preventive measures based on clinical signs. Therefore, reliable diagnostic tool for timely reporting of suspected diseases is very much essential. A novel one-step triplex PCR assay was developed and evaluated for simultaneous detection of three important viruses namely porcine circovirus type 2 (PCV2), porcine parvovirus (PPV) and classical swine fever virus (CSFV) involved in reproductive problems in pigs. Each of the three pairs of oligonucleotide primers exclusively amplified the targeted fragment of the specific viruses. The multiplex PCR assay was found to be sensitive in detecting at least 300 pg of viral genomic DNA or RNA from a mixture of three viruses in a reaction. No amplification was obtained from other common viruses or pathogens, such as porcine reproductive and respiratory syndrome virus (PRRSV), Japanese encephalitis virus (JEV), porcine group A rotavirus (PoRVA), Escherichia coli and Staphylococcus aureus thereby indicating that the developed multiplex PCR has high specificity. Because of the sensitivity and specificity, the developed multiplex PCR assay will be a useful tool for clinical diagnosis of mixed infections of DNA and RNA viruses in pigs.

Development of a rapid loop-mediated isothermal amplification (LAMP) assay for visual detection of porcine parvovirus (PPV) and its application.

Porcine parvovirus (PPV) infection is one of the most important causes of reproductive failure in pigs impacting the piggery industry globally with huge economic losses. A cost-effective, simple, rapid, specific, and sensitive method is critical for monitoring PPV infection on pig farms. The main aim of the present study was to develop and evaluate a loop-mediated isothermal amplification (LAMP) assay for rapid visual detection of porcine parvovirus (PPV) in pigs. A set of six LAMP primers including two outer primers, two inner primers, and two loop primers were designed utilizing the conserved region of capsid protein VP2 gene sequences of PPV and was applied for detection of PPV from porcine samples. Time and temperature conditions for amplification of PPV genes were optimized to be 30 min at 63 °C. The developed assay was ten-fold more sensitive than conventional PCR with analytical sensitivity of 20 pg and 200 pg, respectively. This is the first report of detection of PPV by LAMP assay from India. The assay did not cross-react with porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), or classical swine fever virus (CSFV). The LAMP assay was assembled into a LAMP assay kit of 20 reactions and was validated in different laboratories in India. The newly developed LAMP assay was proved to be a specific, sensitive, rapid, and simple method for visual detection of PPV which does not require even costly equipments for performing the test. It complements and extends previous methods for PPV detection and provides an alternative approach for detection of PPV.

Development and application of a triplex-PCR assay for rapid detection of methicillin-resistant Staphylococcus aureus from pigs.

A triplex-PCR assay was developed and evaluated for rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) recovered from various biological samples of pig. Three sets of primers were designed to target mecA, 16S rRNA and nuc genes of MRSA. The specific amplification generated three bands on agarose gel, with sizes 280 bp for mecA, 654 bp for 16S rRNA and 481 bp for nuc, respectively. A potential advantage of the PCR assay is its sensitivity with a detection limit of 102  CFU per ml of bacteria. In all, 79 MRSA isolates recovered from various samples of pigs were subjected to the amplification by the triplex-PCR assay and all the isolates yielded three bands corresponding to the three genes under this study. No false-positive amplification was observed, indicating the high specificity of the developed triplex-PCR assay. This assay will be a useful and powerful method for differentiation of MRSA from methicillin-sensitive S. aureus, coagulase-negative methicillin-resistant staphylococci and coagulase-negative methicillin-sensitive staphylococci.

Pimply gut condition in mithun (Bos frontalis) calves.

The present observation was recorded at National Research Centre on Mithun, Jharnapani from May 2010 to September 2012. A total of 15 mithun calves, which died in and around Jharnapani, were attended and detailed post-mortem examination was carried out. Out of these, five calves (33.33 %) aging between 1 and 1.5 years exhibiting the condition of chronic wasting and diarrhoea were found positive for pimply gut condition based on gross and microscopic examination. Post-mortem examination revealed extensive nodule formation on the wall of the rectum; however, the entire lumen did not reveal any of adult parasites. In all the cases, there were congestion in the mucous layer and thickening of the intestinal wall. Histopathological examination revealed chronic enteritis with mononuclear cell infiltration comprising mostly of macrophages, lymphocytes and eosinophils. In the muscularis mucosae, encysted larvae were found along with fibrous tissue proliferation. These lesions gave the intestine a nodular appearance as they thickened the wall and projected from the serosal surface. These extensive numbers of nodules in the intestine might have interfered with peristalsis and intestinal absorption which led to chronic wasting and diarrhoea in the calves.

SCC mec typing and antimicrobial resistance of methicillin-resistant Staphylococcus aureus (MRSA) from pigs of Northeast India.

Staphylococcus aureus is one of the most important pathogens of both humans and animal. Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen that causes serious infections both in hospitals and communities due to its multidrug resistance tendency. This study was undertaken to characterize the MRSA isolates from pigs and to determine the antimicrobial resistance of these isolates. Forty nine MRSA strains (one strain per positive pig) isolated from pigs of Northeast India were characterized by SCCmec typing and antimicrobial resistance. The overall prevalence of MRSA was 7.02 % with the highest prevalence recorded in pigs aged 1-3 months (P = 0.001) and in nasal samples (P = 0.005). Two SCC mec types (type III and V) were found in Indian pigs with predominance of type V. All isolates were resistant to penicillin. Seventeen resistance groups were observed where 87.75 % isolates showed multidrug resistance (showed resistance to three or more classes of antimicrobials). The most predominant resistance pattern observed was Oxytetracycline + Penicillin + Sulfadiazine + Tetracycline accounting 12.24 % of the isolates. The present study contributes to the understanding of characteristics and antimicrobial resistance of porcine MRSA isolates which in turn will help in devising strategy for the control of this pathogen. Findings of the study also throw light on multidrug resistance MRSA and emphasize the need for judicious use of antimicrobials in animal practice.