Molecular Analysis of Classical Swine Fever Virus Associated Field Infections Evidence Novel CSFV Sub Genotype in Tamil Nadu, Southern India.

Classical swine fever (CSF) is an endemic and major viral infection of Indian swine husbandry, contributing to great economic losses with multiple genotypes associated with vast clinical and subclinical outcomes. Molecular detection and genotyping of CSF virus directly from field samples has great application in disease monitoring and control measures hence this study aimed to isolate and characterize CSFV genotypes circulating in southern states of India. Fifty-seven porcine post-mortem tissues (lymph nodes, spleens, livers, lungs, and kidneys) collected from pigs suspected of systemic infections and sudden death with the history of live attenuated CSF vaccination from different regions of Tamil Nadu were used in this study. An NS5B gene based CSFV specific RT-PCR screening confirmed CSFV positivity in 7% (4/57) of samples with a specific amplicon of 449 bp. Further molecular screening for other viral co-infections such as PCV2, PPV and PRRSV done by specific individual PCR assays to all the samples. Non-involvement of above screened three viral pathogens in all four field samples which showed positivity for CSFV confirming CSFV as primary pathogen. Two RT-PCR positive samples (TNI-4 and CHNL-2) selected randomly and sequenced. Aligned contig sequences of both samples were subjected to BLAST homology search and phylogentic characterization. BLAST study of TNI-4 sequence revealed 99% sequence identity with Indian CSFV sequences of genotype 1 and CHNL-2 showed 98% sequence identity with Indian CSFV sequences of genotype 2. Phylogenetic analysis of the TNI-4 and CHNL-2 sequences obtained in this study along with 38 published CSFV sequences consisting of all 5 new genotypes and 14 sub genotypes through the Maximum Likelihood tree method in MEGA 11 revealed that TNI-4 clustering together with 1.7 sub genotypes and CHNL-2 clustering together with 2.2 sub genotypes. TNI-4 and CHNL-2 partial NS5B gene sequences obtained in this study deposited in the GenBank database under accession numbers of MW822568 and MW822569 respectively. The study is the first to report CSF infections associated with the newer 1.7 sub genotype in Tamil Nadu, southern India. It is possible that vaccination could affect the genetic diversity of the CSFV through recombination and point mutations for immune evasion.

Molecular epidemiology of goat pox viruses.

Goat pox disease outbreaks were observed in different places affecting Black Bengal Goats in West Bengal (WB) and Tellicherry, Vembur and non-descriptive breeds in Tamil Nadu (TN) causing severe lesions and mortality up to 30%. Clinical specimens from all the outbreaks were screened by polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) and confirmed the diseases as Goat Pox. Virus isolation in Vero cell line was done with randomly selected ten samples, cytopathic effects (CPE) characterized by syncytia and intracytoplasmic inclusion bodies were observed after several blind passages. Nucleotide sequence of complete p32 gene using randomly selected two isolates and three clinical specimens revealed presence of Goat pox virus (GTPV)-specific signature residues in all the sequences. Phylogenetic analysis using the present five sequences along with GenBank data of GTPV complete p32 gene sequences showed all the GTPV sequences cluster together except Pellor strain (NC004003) and FZ Chinese strain (KC951854). The five sequences either from WB or TN cluster more closely with GTPV isolates of Maharashtra state that were responsible for cross species outbreak of pox disease in both sheep (KF468759) and goats (KF468762) in India during the year 2010. All the Indian goat pox viruses, including the Mukteswar strain, isolated in 1946 and sequence reported in 2004 clustered together with the GTPVs causing the recent outbreaks. It was observed that GTPVs caused similar clinical manifestation irrespective of their geographical locations and breed characteristics, no variation observed among the Indian isolates based on p32 gene over the period of seventy years and disease outbreaks could not be observed or reported in vaccinated goats.

Fatal peste des petits ruminants disease in Chowsingha.

This communication reports fatal Peste des petits ruminants (PPR) disease in Chowsingha (Tetracerus quadricornis), a member of the subfamily Bovinae and family Bovidae captured in a Zoological Park. The animals showed clinical signs of acute respiratory disease with frothy nasal discharge (1-2 days) and mortality of twenty animals (80%) within 48 hr. Necropsy of dead Chowsingha showed haemorrhagic patches in trachea and severe congestion of lungs and ocular mucosa. There was no characteristic lesion in the intestine. Swabs from trachea and nasal tract along with tissue samples of spleen and lung from dead animals were found positive for PPR virus based on reverse transcription-polymerase chain reaction using H gene and partial N gene-specific primers. Sequence analysis of complete H gene and partial N gene confirmed the aetiological agent as PPR virus lineage IV. The identity of the Chowsingha tissues used for PPRV isolation was confirmed by the 12S ribosomal RNA gene sequencing, and the amplified gene was analysed identically to the Chowsingha mitochondrial 12S ribosomal RNA gene. The present information of PPR in Chowsingha is the first report of PPRV lineage IV causing cross-species fatal disease in subfamily bovinae and family Bovidae. The acute manifestation of the disease indicates high susceptibility of this vulnerable wild bovid species to PPR lineage IV. This report extends host range and demands enhanced surveillance among subfamily bovinae to strengthen PPR eradication programme.

Emergence of Porcine Circovirus 2 Associated Reproductive Failure in Southern India.

Incidence of unusually high numbers of stillbirths was observed at a piggery unit at the Veterinary University research farm in Tamil Nadu State of India. Systematic examination of the tissue from stillborn piglets led to the identification of presence of Porcine circovirus 2 (PCV2). Detailed analysis utilizing electron microscopy, polymerase chain reaction and sequencing confirmed the presence of PCV2 in the tissue of affected piglets. Histopathology analysis of the affected piglet tissue showed lymphoid cell depletion of lymphnodes, spleen and infiltration of liver, kidney, myocardium, etc. Retrospective examination of the morbidity and mortality history in the farm revealed high mortality in young and weanling piglets suggestive of PCV2 infection-induced diseases. This is the first report of emergence of major disease incidence in farmed swine due to PCV2 infection in India.