A new genotype of nephropathogenic infectious bronchitis virus circulating in vaccinated and non-vaccinated flocks in China

Abstract

Five strains of infectious bronchitis virus (IBV) were isolated from five layer flocks that had nephropathogenic infection in four provinces in China. Among them, three of the five flocks had been vaccinated against infectious bronchitis. Virulence studies indicated that the five Chinese IBV isolates caused 10 to 30% mortality in 15-day-old specific pathogen free chickens and gross lesions were mainly confined to the kidneys in all of the dead chickens. Two oligonucleotide pairs, S1Uni2 and S1Oligo3' or S1Oligo5' and S1Oligo3', were used after propagation of the isolates in embryonated eggs to amplify the S1 protein genes of the spike protein. The cDNA derived by reverse transcriptase-polymerase chain reaction was cloned and sequenced. The nucleotide and amino acid sequence of S1 protein gene had a similar degree of identity (> or =92%) among the five Chinese IBV isolates. The nucleotide and amino acid identity of the S1 protein gene between the five Chinese IBV isolates and 16 strains of other IBVs varied from 60 to 81%. This clearly showed that the five Chinese IBV isolates comprised a separate genotype. These results demonstrated, for the first time, that there is a new genotype of nephropathogenic IBV circulating in vaccinated and non-vaccinated flocks in China.

Isolation of avian infectious bronchitis coronavirus from domestic peafowl (Pavo cristatus) and teal (Anas)

“…Virulence studies revealed that this isolate is a nephropathogenic coronavirus strain and it caused morbidity and mortality of 100 and 80 %, respectively, upon infection of 15-day-old chicks. It has been reported that nephropathological IBVs have been circulating widely in recent years in vaccinated and non-vaccinated flocks in China (Wu et al, 1998;Li & Yang, 2001;Liu & Kong, 2004). Sequence analysis showed that, although tl/CH/LDT3/03 contained a 6 nt deletion at the 39 end of gene 3 compared with most other IBV strains, this deletion has also been reported in other IBV isolates (Cavanagh & Davis, 1988;Cavanagh et al, 1992;Jia & Naqi, 1997).…”

“…PCR products were excised from 1?0 % agarose gels and purified by using an agarose gel DNA extraction kit (Boehringer Mannheim). Purified PCR products were cloned into a TA cloning vector (TaKaRa) by following the manufacturer's instructions or cloned as described previously (Liu & Kong, 2004). Three independent clones of each PCR product were sequenced by using M13 sequencing primers.…”

“…Reverse transcription was carried out in a 40 ml reaction mixture containing 20 ml RNA by using a consensus IBV oligonucleotide [N(2), 59-TGTACCCTCGATCGTACTCCGCGT-39] specific for the 39 untranslated region (UTR), as well as random hexamers (Liu & Kong, 2004).…”

“…By using an additional set of four primer pairs (Table 1), 'targeted gene-walking PCR ' (Parker et al, 1991;Chang et al, 2001) was used to amplify further viral RT-PCR products. The general conditions for RT-PCR have been described previously (Liu & Kong, 2004).Cloning, sequencing and sequence analysis. PCR products were excised from 1?0 % agarose gels and purified by using an agarose gel DNA extraction kit (Boehringer Mannheim).…”

Prevalence of infectious bronchitis and Newcastle disease virus among domestic and wild birds in H5N1 outbreaks areas

“…Intensive research and survey on these diseases has been conducted in developed countries because of their impact on the economy and possible transmission to humans. The poultry business is traditionally managed and is of wide interest to many farmers but few studies have been done in African countries to survey these threatening infectious diseases, which has led to high losses of poultry birds [1,6,[7][8][9][10][11][12]18,19]. Unfortunately, these two diseases have not been previously studied in Burkina Faso despite the importance of the poultry industry in this country; approximately 32 million chickens per year are slaughtered.…”