ABSTRACT
Group A rotaviruses (GAR) are an important cause of diarrhoea in infants and newborn animals especially pigs. In this paper, we report the detection, G and P typing and phylogenetic analysis of GAR of pigs in Kerala. A total of 100 fecal samples from diarrhoeic piglets were collected from organized farms in Wayanad, Ernakulam, Thrissur, and Palakkad districts of Kerala. The samples were tested for the presence of GAR employing reverse transcriptase polymerase chain reaction (RT-PCR) targeting VP6 gene. Positive samples were tested by G and P genotyping primers and representative amplicons were sequenced. Of the 100 samples, 12 were positive for GAR. The G and P types detected were G2, G4, G5, G6, G9, P[6] and P[19]. An untypable P type (P21-5 like) was also detected. In some of the samples more than one G type was detected. The nucleotide sequences of G2, G4 and G5 types were similar to those seen in pigs and that of G6 was similar to bovine sequences. G9, P[6] and P[19] sequences showed similarity to human rotavirus sequences. The findings of this study provide the first information on the G and P genotypes of GAR of pigs in Kerala.
ABSTRACT
Porcine reproductive and respiratory syndrome (PRRS) caused by an arterivirus is characterised by reproductive disorders in sows, and post-weaning pneumonia and growth reduction in piglets. Though the virus has been detected in Kerala, no systematic study has been carried out to ascertain its genotype and molecular epidemiology. In the present study, 7 PRRS virus (PRRSV) positive samples collected from incidences of PRRS in Kerala during 2017-2019 were subjected to ORF5, ORF7 and Nsp2 gene based reverse transcription polymerase chain reaction and the specific amplicons generated were sequenced. On BLAST analysis it was revealed that all the sequences were of genotype 2 (North American genotype). Phylogenetic analysis of ORF5 sequences, grouped them under subgenotype 4 with close clustering with other isolates from Kerala, Mizoram and Assam. Nsp2 gene sequence based phylogenetic analysis grouped the isolates under subgenotype 3 with similarities to isolates from Mizoram. Phylogenetic analysis based on ORF7, clustered the isolates under study with PRRSV isolates from Mizoram and Meghalaya. In Nsp2 sequences, a 30 amino acid discontinuous deletion was observed. On analysis of amino acid sequences of ORF5 of Kerala isolates and those from India, it was seen that the Kerala isolates showed closer similarity to PRRSV isolates from Assam than to the other Indian isolates. The study reveals that PRRSV strains prevalent in Kerala share close relationship with other PRRSV isolates in India. This may be due to spread of the virus from these regions to Kerala due to animal movement. Concerted efforts should be undertaken to check unauthorized animal movement to control spread of this economically important disease.
ABSTRACT
Recurrent infectious bursal disease (IBD) outbreaks were reported in different regions of Kerala, India. This paper reports the comparative genetic analysis of the hypervariable region of the VP2 gene of IBD virus isolates from the field outbreaks in Kerala. In phylogenetic analysis, the obtained field isolates fall into genogroup 1 and 3. In genogroup 3, all vvIBDV isolates shared a common ancestor with other south Indian isolates but isolates 9/CVASP/IBDV, 10/CVASP/IBDV, 12/CVASP/IBDV, 14/CVASP/IBDV and 17/CVASP/IBDV are most recently evolved and are diverged from the south Indian isolates. The amino acid sequence of 22 isolates was analysed, out of which 18 had conserved amino acids which were characteristic of vvIBDV. All the vvIBDV isolates obtained in the study had phenylalanine and valine at the position 240 and 294, respectively, similar to recently evolved Indian IBDV isolate (MDI14). But we observed T269A and S299N mutations in the isolate 6/CVASP/IBDV, and it is the first report of such mutations at these positions in India IBDV isolates. The isolate 11/CVASP/IBDV had a unique mutation of V225A which is not yet reported in IBDV isolates. Two isolates (15/CVASP/IBDV and 18/CVASP/IBDV) were 100% amino acid similar to intermediate plus vaccine strain. The isolates 8/CVASP/IBDV/VP2 and 19/CVASP/IBDV had amino acids unique for the intermediate vaccine with mutations observed at H253Q and V256I in 19/CVASP/IBDV, T270A and novel mutation N279Y in isolate 8/CVASP/IBDV. These two isolates had non-virulent classical heptapeptide sequence 'SWSARGS'; nevertheless, they produce field outbreaks of IBD. This is the first report of genetic characterisation of IBDV in Kerala, India.
