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Genotyping and pathotyping of diversified strains of infectious bronchitis viruses circulating in Egypt.

ABSTRACT: AIM:To characterize the circulating infectious bronchitis virus (IBV) strains in Egypt depending on the sequence of the spike-1 (S1) gene [hypervariable region-3 (HVR-3)] and to study the pathotypic features of these strains. METHODS:In this work, twenty flocks were sampled for IBV detection using RRT-PCR and isolation of IBV in specific pathogen free (SPF) chicks during the period from 2010 to 2015. Partial sequencing and phylogenetic analysis of 400 bp representing the HVR-3 of the S1 gene was conducted. Pathotypic characterization of one selected virus from each group (Egy/Var-I, Egy/Var-II?and classic) was evaluated in one day old SPF chicks. The chicks were divided into 4 groups 10 birds each including the negative control group. Birds were inoculated at one day by intranasal instillation of 10(5)EID50/100 ?L of IBV viruses [IBV-EG/1212B-2012 (Egy/Var-II), IBV/EG/IBV1-2011 (Egy/Var-I) and IBV-EG/11539F-2011 (classic)], while the remaining negative control group was kept uninfected. The birds were observed for clinical signs, gross lesions and virus pathogenicity. The real-time rRT-PCR test was performed for virus detection in the tissues. Histopathological examinations were evaluated in both trachea and kidneys. RESULTS:The results revealed that these viruses were separated into two distinct groups; variant (GI-23) and classic (GI-1), where 16 viruses belonged to a variant group, including 2 subdivisions [Egy/Var-I (6 isolates) and Egy/Var-II (10 isolates)] and 4 viruses clustered to the classic group (Mass-like). IBV isolates in the variant group were grouped with other IBV strains from the Middle East. The variant subgroup (Egy/Var-I) was likely resembling the original Egyptian variant strain (Egypt/Beni-Suif/01) and the Israeli strain (IS/1494/2006). The second subgroup (Egy/Var-II) included the viruses circulating in the Middle East (Ck/EG/BSU-2 and Ck/EG/BSU-3/2011) and the Israeli strain (IS/885/00). The two variant subgroups (Egy/Var-I and Egy/Var-II) found to be highly pathogenic to SPF chicks with mortalities up to 50% than those of the classic group which was of low virulence (10% mortality). Pathogenicity indices were 25 (Egy/Var-II), 24 (Egy/Var-I) and 8 (classic); with clinical scores 3, 2 and 1 respectively. CONCLUSION:These findings indicated that the recent circulating Egyptian IBVs have multiple heterogeneous origins in marked diversifying nature of their spread, with high pathotype in specific pathogen free chicks.

SUBMITTER: Zanaty A

PROVIDER: S-EPMC4981825 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Genotyping and pathotyping of diversified strains of infectious bronchitis viruses circulating in Egypt.

Zanaty Ali A Arafa Abdel-Satar AS Hagag Naglaa N El-Kady Magdy M

World journal of virology 20160801 3

<h4>Aim</h4>To characterize the circulating infectious bronchitis virus (IBV) strains in Egypt depending on the sequence of the spike-1 (S1) gene [hypervariable region-3 (HVR-3)] and to study the pathotypic features of these strains.<h4>Methods</h4>In this work, twenty flocks were sampled for IBV detection using RRT-PCR and isolation of IBV in specific pathogen free (SPF) chicks during the period from 2010 to 2015. Partial sequencing and phylogenetic analysis of 400 bp representing the HVR-3 of ...[more]

PMID: 27563538

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Project description:Gammacoronavirus infectious bronchitis virus (IBV) causes an economically important respiratory disease of poultry. Protective immunity is associated with the major structural protein, spike (S) glycoprotein, which induces neutralising antibodies and defines the serotype. Cross-protective immunity between serotypes is limited and can be difficult to predict. In this study, the ability of two recombinant IBV vaccine candidates, BeauR-M41(S) and BeauR-4/91(S), to induce cross-protection against a third serotype, QX, was assessed. Both rIBVs are genetically based on the Beaudette genome with only the S gene derived from either M41 or 4/91, two unrelated serotypes. The use of these rIBVs allowed for the assessment of the potential of M41 and 4/91 S glycoproteins to induce cross-protective immunity against a heterologous QX challenge. The impact of the order of vaccination was also assessed. Homologous primary and secondary vaccination with BeauR-M41(S) or BeauR-4/91(S) resulted in a significant reduction of infectious QX load in the trachea at four days post-challenge, whereas heterologous primary and secondary vaccination with BeauR-M41(S) and BeauR-4/91(S) reduced viral RNA load in the conjunctiva-associated lymphoid tissue (CALT). Both homologous and heterologous vaccination regimes reduced clinical signs and birds recovered more rapidly as compared with an unvaccinated/challenge control group. Despite both rIBV BeauR-M41(S) and BeauR-4/91(S) displaying limited replication in vivo, serum titres in these vaccinated groups were higher as compared with the unvaccinated/challenge control group. This suggests that vaccination with rIBV primed the birds for a boosted humoral response to heterologous QX challenge. Collectively, vaccination with the rIBV elicited limited protection against challenge, with failure to protect against tracheal ciliostasis, clinical manifestations, and viral replication. The use of a less attenuated recombinant vector that replicates throughout the respiratory tract could be required to elicit a stronger and prolonged protective immune response.

Project description:AimThis study aimed to detect and characterize current genotypes of canine parvovirus (CPV) in Egypt during 2018.Materials and methodsA total of 50 fecal swabs were collected from clinically infected domestic dogs of 2-5 months of age, suspected to suffer from CPV infection, from Cairo and Giza Governorates. The samples were subjected to qualitative antigen detection using the rapid test, followed by isolation on Madin-Darby Canine Kidney (MDCK) cells, molecular characterization with partial amplification of VP2 gene using polymerase chain reaction (PCR), followed by sequencing and phylogenetic analysis.ResultsOut of 50 fecal samples, 20 samples were positive (40%) by Rapid CPV/canine coronavirus Ag Test Kit. These positive samples were cultured successfully on MDCK cells. Nine randomly chosen samples out of 30 apparently negative samples were amplified using PCR with primers Hfor and Hrev to yield a typical 630 bp fragment. Then, six randomly chosen samples out of nine were amplified using PCR with primers Pbs and Pbas to yield a typical 427 bp fragment. Sequencing, BLAST analysis and assembly of the two fragments (630 bp and 427 bp) to produce 912 bp fragments, in the six samples, revealed two serotypes CPV-2b and CPV-2c. The obtained strains were submitted to GenBank and given accession numbers MK642272, MK642273, MK642274, MK642275, MK642276, and MK642277. Phylogenetic analysis of the Egyptian strains serotype 2b illustrated that they were closely related to Thailand strains (accession numbers KP715709, KP715694, KP715701, and KP715700); while Egyptian strains serotype 2c was closely related to Thailand strains (accession numbers MH711894 and MH711902), Taiwanese strain (KU244254), Chinese strain (MF467242), and Vietnamese strain (accession number LC216910).ConclusionThe current research recommends further epidemiological studies to assess the extent of the occurrence of different serotypes of CPV in Egypt and the efficiency of imported and locally produced vaccines in protection against CPV infection.

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Genotyping and pathotyping of diversified strains of infectious bronchitis viruses circulating in Egypt.

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Genotyping and pathotyping of diversified strains of infectious bronchitis viruses circulating in Egypt.

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