Sequence and Phylogenetic Analyses of the Structural Genes of Virulent Isolates and Vaccine Strains of Peste Des Petits Ruminants Virus from India

Abstract

Peste des petits ruminants (PPR) is an acute, highly contagious, notifiable and economically important transboundary viral disease of sheep and goats. In this study, sequence and phylogenetic analyses of structural protein genes, namely the nucleocapsid (N), the matrix (M), the fusion (F) and the haemagglutinin (H) coding sequences of virulent and vaccine strains of PPR virus (PPRV), were undertaken to determine the genetic variations between field isolates and vaccine strains. The open reading frame (ORF) of these genes of the isolates/strains was amplified by RT-PCR, cloned and sequenced. The ORF of N, M, F and H genes was 1578, 1008, 1641 and 1830 nucleotides (nt) in length and encodes polypeptides of 525, 335, 546 and 609 amino acids (aa), respectively, as reported earlier. Comparative sequence analyses of these four genes of isolates/strains were carried out with published sequences. It revealed an identity of 97.7-100% and 97.7-99.8% among the Asian lineage IV and 89.6-98.7% and 89.8-98.9% with other lineages of PPRV at nt and aa levels, respectively. The phylogenetic analyses of these isolates based on the aa sequences showed that all the viruses belonged to lineage IV along with other Asian isolates. This is in agreement with earlier observations that only PPRV lineage IV is in circulation in India since the disease was first reported. Further, sequence analysis of the thermostable/thermo-adapted vaccine strains showed no significant changes in the functional or structural surface protein-coding gene sequences. It is important to monitor the circulation of the PPRV in susceptible animals by H gene-based sequence comparisons in addition to the F gene- and N gene-based approaches to identify the distribution and spread of virus in the regular outbreaks that occur in endemic countries like India.

Diagnosis and control of peste des petits ruminants: a comprehensive review

“…The disease incidence has been in decline over the past 5 years as per analysis of outbreak data available in National Animal Disease Referral Expert System (NADRES), PD_ADMAS (unpublished data). In India, decreased numbers of outbreaks as well as changes in the severity of disease patterns recently observed might be due to the effectiveness of live attenuated vaccines, timely vaccination of sheep and goats, and circulation of a single Asian lineage IV PPRV, since the disease was first reported in India [14]. Currently vaccination programs are being implemented in some states of India which will alter PPR epidemiology, particularly distribution of the disease and pattern of disease [8,134].…”

“…Based on this approach, the IVRI, Mukteswar, India have been successful in developing intrinsic live attenuated Thermo-adapted (Ta) PPR vaccines (goat and sheep isolates) employing thermo-adapted Vero cell line, which is adapted to grow at 40°C [14,114]. The vaccines have undergone successful in-house trials in both the sheep and goats either as single [125,Balamurugan et al,unpublished data], or in combination with sheeppox or goatpox as bivalent or Orf as trivalent vaccines (unpublished data).…”

“…Various primers sets derived from 'N', 'F' and 'P' genes were described to detect and differentiate between RP and PPR by various workers [21,35,53]. The PCR techniques have been developed targeting F gene [53], N gene [35,57], M gene [7,57] and H gene [14,69] and used for specific detection of PPRV from clinical samples. A PCR for PPRV/RPV using PPR virus-specific external protein F gene primer (F1 and F2) [53] has gained great importance for differential diagnosis and for epidemiological studies.…”

“…It is divided into six transcriptional units encoding two non-structural proteins (V, C) and six structural proteins: the surface glycoproteins which include fusion (F) and Haemagglutinin (H) proteins, the matrix protein (M), the nucleoprotein (N), and the phosphoprotein (P) which forms the polymerase complex in association with large (L) protein [36,42,61,129]. The PPRV is genetically grouped into four lineages (I, II, III, and IV) based on the F and N gene sequences analyses [14,39,70,128]. Lineages I-III circulate in Africa, while lineage IV is generally found in Asia [39,128].…”

Autophagy enhances the replication of Peste des petits ruminants virus and inhibits caspase-dependent apoptosis in vitro

“…The PPRV genome of approximately 16 kilobases (kb) encodes six structural proteins, namely, the nucleocapsid (N), phospho (P), matrix (M), fusion (F), haemagglutinin (H) and large (L) proteins in the 3′ to 5′ direction (3′-N-P-M-F-H-L-5′); two non-structural proteins (C/V) are also encoded due to the RNA editing of the phosphoprotein gene. Four different lineages of PPRV (I, II, III, and IV) have been defined worldwide based on the molecular epidemiology of the “N” and “F” gene sequences of the virus [5,6]. PPRV is currently endemic in most of Africa, the Middle East, South Asia and China and causes significant economic losses [2,7].…”