Summary： Recently, suppressor of cytokine signaling-3 （SOCS3） has been shown to be an inducible endogenous negative regulator of Janus kinase/signal transducers and activators of transcription （JAK/STAT） pathway ...Summary： Recently, suppressor of cytokine signaling-3 （SOCS3） has been shown to be an inducible endogenous negative regulator of Janus kinase/signal transducers and activators of transcription （JAK/STAT） pathway which is relevant in inflammatory response, while its functions in acute liver failure and HBV-induced acute-on-chronic liver failure （HBV-ACLF） have not been fully elucidated. In this study, we explored the role of SOCS3 in the development of mouse hepatitis virus strain 3 （MHV-3）-induced acute liver failure and its expression in liver and peripheral blood mononuclear cells （PBMCs） of patients with HBV-ACLF. Inflammation-related gene expression was detected by real-time PCR, immtmohistochemistry and Western blotting. The correlation between SOCS3 level and liver injury was studied. Our results showed that the SOCS3 expression was significantly elevated in both the liver tissue and PBMCs from patients with HBV-ACLF compared to mild chronic hepatitis B （CHB）. Moreover, a time course study showed that SOCS3 level was increased remarkably in the liver of BALB/cJ mice at 72 h post-infection. Pro-inflammatory cytokines, interleukin （IL）-1 β, IL-6, and tumor necrosis factor （TNF）-α, were also increased significantly at 72 h post-infection. There was a close correlation between hepatic SOCS3 level and IL-6, and the severity of liver injury defined by alanine aminotransferase （ALT） and aspartate aminotransferase （AST） levels, respectively. These data suggested that SOCS3 may play a pivotal role in the pathogenesis of MHV-3-induced acute liver failure and HBV-ACLF.展开更多
According to the previously published CSFV sequences, 18 paris of partially overlapping primers which span the entire genome of CSFV strain Shimen were designed and synthesized. Each cDNA fragment of strain Shimen was...According to the previously published CSFV sequences, 18 paris of partially overlapping primers which span the entire genome of CSFV strain Shimen were designed and synthesized. Each cDNA fragment of strain Shimen was amplified by RT-PCR method from the anticoagulant blood of strain Shimen infected pig. The PCR fragments were cloned into pGEM-T vector respectively and sequenced. The results show that we have obtained the nucleotide sequence of strain Shimen. The viral RNA consists of 12 297 nucleotides including noncoding regions of 373 and 227 bases at the 5′ and 3′ end, respectively, and a single large open reading frame spanning 11 697 nucleotides in the middle, which encodes an amino acid sequence of 3 989 residues with a calculated molecular weight of 437.6×103. The precisely sequencing of 5′ and 3′ termini is undertaking.展开更多
Summary： The role of hepatic CD69＋ natural killer （NK） cells in virus-induced severe liver injury and subsequent hepatic failure is not well defined. In this study, a mouse model of fulminant liver failure （FHF）...Summary： The role of hepatic CD69＋ natural killer （NK） cells in virus-induced severe liver injury and subsequent hepatic failure is not well defined. In this study, a mouse model of fulminant liver failure （FHF） induced by murine hepatitis virus strain 3 （MHV-3） was used to study the role of hepatic CD69＋NK cells in the development of FHF. The CD69 expression in NK cells in the liver, spleen, bone marrow and peripheral blood was detected by using flow cytometry. The correlation between the CD69 level in hepatic NK cells and liver injury was studied. The functional marker （CD107a）, and activating and inhibitory receptor （NKG2D and NKG2A） expressed on CD69＋NK cells and CD69-NK cells were detected by using flow cytometry. Pro-inflammatory cytokines （IL-9, IFN-y and TNF-a） were also examined by using intracellular staining. After MHV-3 infection, the number of CD69＋NK cells in the liver of BALB/cJ mice was increased markedly and peaked at 72 h post-infection. Similar changes were also observed in the spleen, bone marrow and peripheral blood. Meanwhile, the CD69 expression in hepatic NK cells was highly correlated with the serum level of ALT and AST. The expression of CD107a and NKG2D, as well as the production of TNF-a, IFN-7 and IL-9 in hepatic CD69＋NK cells was all significantly up-regulated during 48-72 h post-infection. In contrast, the NKG2A expression was increased in hepatic CD69-NK cells but not in CD69＋NK cells. These results suggested that hepatic CD69＋NK cells play a pivotal role in the pathogenesis of FHF by enhancing degranulation and cytotoxic ability of NK cells and increasing the production of pro-inflammatory cytokines.展开更多
Novel coronavirus pneumonia(COVID-19)is a highly pathogenic infectious disease caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Until now,the new crown pneumonia has caused hundreds of millions of...Novel coronavirus pneumonia(COVID-19)is a highly pathogenic infectious disease caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Until now,the new crown pneumonia has caused hundreds of millions of people worldwide to be infected.Novel coronavirus pneumonia is still a high level of variation.Due to the high variability of COVID-19,there are already a large number of COVID-19 variant strains that are still at a high level of infection worldwide.Recently,WHO(WHO)released a new variant,"Mu"(μ,B.1.621)may be a high vaccine tolerance.This paper reviews the latest research progress of"Mu"virus strain in detail.展开更多
To detect retrospectively the phenotype and stability of the E-protein gene in Japanese Encephalitis （JE） virus strain SA14-14-2 used in the live-attenuated JE vaccine prepears, the viral titer was titrated by plaqu...To detect retrospectively the phenotype and stability of the E-protein gene in Japanese Encephalitis （JE） virus strain SA14-14-2 used in the live-attenuated JE vaccine prepears, the viral titer was titrated by plaque formation in BHK-21 cell cultures, and the neuro-virulence of viruses was assayed in mice with body weight of 12-14 g by intracerebral inoculation. Meanwhile, the total RNA of virus gene was extracted and amplified by RT-PCR with the designed primers, and then it was purified and cloned to the expression vector pGEM-T. The recombinant plasmid was purified and sequenced. It was found that the loss of viral titer of vaccines stored in -20℃ for longer than 10 years was less than 0.5 Lg PFU/ml. No mice inoculated intracerebrally showed signs of illness or even death. The size of plagues of the vaccine virus remained to be small, and the E genes of primary virus seed SA14-14-2 and the vaccines prepared at different years （1987-2001） were unchanged, in- cluding the 8 critical amino acid sites which were different from the parent wild virus strain SA14 and the related neuro-virulence. These results indicate that the genotypic and biological characteristics of the attenuated JE virus strain SA14-14-2 and its vaccines sion noted. prepared are quite stable without any reversion noted.展开更多
The objective of this paper was to analyze the E2 genetic characterization of HB-DCZ strain of Bovine viral diaxrhca Virus （BVDV） which wcrc amplified by RT-PCR and isolated from China. The product of PCK was cloned...The objective of this paper was to analyze the E2 genetic characterization of HB-DCZ strain of Bovine viral diaxrhca Virus （BVDV） which wcrc amplified by RT-PCR and isolated from China. The product of PCK was cloned into pMD18-T vector, and then transfected Escherichia Coli JMI00. The recombinant plasmids were amplified by PCR and were sequenced. From the nucleotide sequence of the amplified products, phylogenetie analyses were performed and genotypes or subgenotypes were identified. The results indicated that the E2 gene fragment of HB-DCZ strain contained 1277bp nucleotides, and had 89.4%, 70.7%, 97.6%, 68.9%, 67.2% sequence similarity with Osloss, OregonC24V, Changchun184, ZM195, NADL, respectively. In conclusion, HB-DCZ strain is closely related to BVDV Osloss, Changchun184, and belongs to subgenotype lb.展开更多
Cucumber green mottle mosaic virus (CGMMV), a member of the Tobamovirus genus, causes a severe disease of cucurbits. In the Moscow region of Russian Federation, the incidence of infection on cucumber plants in greenho...Cucumber green mottle mosaic virus (CGMMV), a member of the Tobamovirus genus, causes a severe disease of cucurbits. In the Moscow region of Russian Federation, the incidence of infection on cucumber plants in greenhouses is high;however, the virus is poorly studied. In this work, the full-length genomes of two pathogenic MC-1 and MC-2 strains of CGMMV isolated from cucumber plants grown in greenhouses in the Moscow region and the attenuated VIROG-43M strain were sequenced. Comparison of VIROG-43M nucleotide sequence with those of the pathogenic strains revealed three missense mutations. Their role in attenuation is discussed. For the first time, in a number of trials conducted under laboratory conditions and in commercial greenhouses, the efficiency of the attenuated VIROG-43M strain as a biocontrol agent for cucumber plant protection resulting in significant yield gain was demonstrated. Phylogenetic analysis with 83 full-length CGMMV coat protein genes isolated in 16 different countries showed that Russian strains are related to isolates from Spain, Greece, USA and Israel.展开更多
[ Objective ] The paper was to prevent the occurrence of broiler avian influenza virus HS subtype Re-8 strain effectively in the breeding process of broilers. [Method] The maternal antibodies of broilers in Beijing Ba...[ Objective ] The paper was to prevent the occurrence of broiler avian influenza virus HS subtype Re-8 strain effectively in the breeding process of broilers. [Method] The maternal antibodies of broilers in Beijing Baochen Hongwang farm were monitored. According to the disappearance law of maternal antibody, the optimal immune time of broiler avian influenza virus H5 subtype Re-8 strain was determined. [ Result] The maternal antibody level of 2-day-old broilers was relatively high, concentrated at 6 log2 -9 log2, and the antibody positive rate was 100%. The maternal antibody level of 8-day-old broilers concentrated at 4 log2 -6 log2, and the antibody positive rate was 100%. The maternal antibody level of 17-day-old broilers concentrated at 0 log2 -3 log2 , and the antibody positive rate was 0. The average maternal antibody level of 24 - 37 days old broilers was 〈 1 log2, and the antibody positive rate was 0. [ Conclusion ] Although the av- erage maternal antibody level of 8-day-old broilers was higher than 5 log2 , 20% of chickens was 4 log2, and maternal antibody could not protect the flock completely. Therefore, the best primary immunization day age of chicks against avian influenza virus was 8 - 10 days of age.展开更多
The mechanisms involved in virus-induced severe hepatitis have not been fully elucidated. In this study, we investigated the role of gamma delta T cell receptors （γδ） T cells in the pathogenesis of fulminant viral...The mechanisms involved in virus-induced severe hepatitis have not been fully elucidated. In this study, we investigated the role of gamma delta T cell receptors （γδ） T cells in the pathogenesis of fulminant viral hepatitis （FVH） induced by murine hepatitis virus strain 3 （MHV-3）. The model of FVH was established by intraperitoneal injection of MHV-3 into Balb/cJ mice. The survival days of mice, and the serum levels of alanine aminotransferase （ALT） and aspartate aminotransferase （AST） were examined. The proportions of γδ T cells in blood, spleen and liver, and cytokines secreted by hepatic γδ T cells were analyzed by flow cytometry. The function of hepatic γδ T cells was examined by cytotoxicity assay. Balb/cJ mice died in 3 to 6 days post MHV-3 infection, with severe hepatic necrosis and significant augmentation of serum ALT and AST levels. The proportions of γδ T cells in blood, spleen and liver were significantly increased post MHV-3 infection, while those of the early activating molecule CD69-expressing γδ T cells and productions of cytokines tumor necrosis factor-alpha （TNF-α） and interferon-y （IFN-3,） increased remarkably in the liver. These highly activated liver γδ T cells were cytotoxic to MHV-3-infected hepatocytes in vitro and this effect of liver γδ T cells against hepatocytes might involve the TNF-α and IFN-γ pathway. These results demonstrated that γδ T cells might contribute to the pathogenesis of MHV-3-induced FVH through the effector cytokines TNF-α and IFN-γ. Key words： fulminant viral hepatitis; murine hepatitis virus strain 3; gamma delta T cell receptors T cells; tumor necrosis factor-a; interferon-α展开更多
Two Marek's disease virus (MDV) field strains were isolated from chickens with tumors independently from Guangdong and Guangxi provinces, and it was confirmed that there were no co-infections with reticuloendothel...Two Marek's disease virus (MDV) field strains were isolated from chickens with tumors independently from Guangdong and Guangxi provinces, and it was confirmed that there were no co-infections with reticuloendotheliosis viruses (REV) in chicken embryo fibroblast cells (CEF) in indirect fluorescence antibody test (IFA) with REV-specific monoclonal antibodies. By dot blot hybridization and PCR of genomic DNA of MDV-infected CEF, it was indicated that LTR fragments of REV genome were integrated into genome of these two MDV field strains. To amplify and clone the integrated REV LTR with MDV sequence at the junction, 4 primers from REV LTR and 7 primers from MDV genome fragment with REV LTR insertion hot points were synthesized and 28 (4x7) pairs of primers (one from REV and another from MDV for each pair) were used in PCR while using the genomic DNA of both strains as the templates. The sequence data demonstrated that both recombinant field strains contained the same REV LTR inserted into MDV at the identical sites in US fragment of the genomes. From the above, it was speculated that both recombinant field MDVs were originated from a same recombinant virus and spread among chicken flocks in two provinces.展开更多
基金supported by the grants from the National Science Foundation of China Advanced Program(No.NSFC81171558,NSFC81271808 and NSFC81030007)Innovation Team Development Plan of the Ministry of Education of China[No.IRT1131(2011)]National Twelfth-Five Years Project in Science and Technology of China(No.2013ZX10002-003)
文摘Summary： Recently, suppressor of cytokine signaling-3 （SOCS3） has been shown to be an inducible endogenous negative regulator of Janus kinase/signal transducers and activators of transcription （JAK/STAT） pathway which is relevant in inflammatory response, while its functions in acute liver failure and HBV-induced acute-on-chronic liver failure （HBV-ACLF） have not been fully elucidated. In this study, we explored the role of SOCS3 in the development of mouse hepatitis virus strain 3 （MHV-3）-induced acute liver failure and its expression in liver and peripheral blood mononuclear cells （PBMCs） of patients with HBV-ACLF. Inflammation-related gene expression was detected by real-time PCR, immtmohistochemistry and Western blotting. The correlation between SOCS3 level and liver injury was studied. Our results showed that the SOCS3 expression was significantly elevated in both the liver tissue and PBMCs from patients with HBV-ACLF compared to mild chronic hepatitis B （CHB）. Moreover, a time course study showed that SOCS3 level was increased remarkably in the liver of BALB/cJ mice at 72 h post-infection. Pro-inflammatory cytokines, interleukin （IL）-1 β, IL-6, and tumor necrosis factor （TNF）-α, were also increased significantly at 72 h post-infection. There was a close correlation between hepatic SOCS3 level and IL-6, and the severity of liver injury defined by alanine aminotransferase （ALT） and aspartate aminotransferase （AST） levels, respectively. These data suggested that SOCS3 may play a pivotal role in the pathogenesis of MHV-3-induced acute liver failure and HBV-ACLF.
文摘According to the previously published CSFV sequences, 18 paris of partially overlapping primers which span the entire genome of CSFV strain Shimen were designed and synthesized. Each cDNA fragment of strain Shimen was amplified by RT-PCR method from the anticoagulant blood of strain Shimen infected pig. The PCR fragments were cloned into pGEM-T vector respectively and sequenced. The results show that we have obtained the nucleotide sequence of strain Shimen. The viral RNA consists of 12 297 nucleotides including noncoding regions of 373 and 227 bases at the 5′ and 3′ end, respectively, and a single large open reading frame spanning 11 697 nucleotides in the middle, which encodes an amino acid sequence of 3 989 residues with a calculated molecular weight of 437.6×103. The precisely sequencing of 5′ and 3′ termini is undertaking.
基金supported by the grants from the National Natural Science Funds for Young Scholar(No.81100308)the National Science Foundation of China Advanced Program(No.NSFC 81030007,and No.NSFC81171558)
文摘Summary： The role of hepatic CD69＋ natural killer （NK） cells in virus-induced severe liver injury and subsequent hepatic failure is not well defined. In this study, a mouse model of fulminant liver failure （FHF） induced by murine hepatitis virus strain 3 （MHV-3） was used to study the role of hepatic CD69＋NK cells in the development of FHF. The CD69 expression in NK cells in the liver, spleen, bone marrow and peripheral blood was detected by using flow cytometry. The correlation between the CD69 level in hepatic NK cells and liver injury was studied. The functional marker （CD107a）, and activating and inhibitory receptor （NKG2D and NKG2A） expressed on CD69＋NK cells and CD69-NK cells were detected by using flow cytometry. Pro-inflammatory cytokines （IL-9, IFN-y and TNF-a） were also examined by using intracellular staining. After MHV-3 infection, the number of CD69＋NK cells in the liver of BALB/cJ mice was increased markedly and peaked at 72 h post-infection. Similar changes were also observed in the spleen, bone marrow and peripheral blood. Meanwhile, the CD69 expression in hepatic NK cells was highly correlated with the serum level of ALT and AST. The expression of CD107a and NKG2D, as well as the production of TNF-a, IFN-7 and IL-9 in hepatic CD69＋NK cells was all significantly up-regulated during 48-72 h post-infection. In contrast, the NKG2A expression was increased in hepatic CD69-NK cells but not in CD69＋NK cells. These results suggested that hepatic CD69＋NK cells play a pivotal role in the pathogenesis of FHF by enhancing degranulation and cytotoxic ability of NK cells and increasing the production of pro-inflammatory cytokines.
基金Huoshenshan Hospital Scientific Research Foundation Project(No.HSS-217)Introduction to the author of the 940 Hospital Fund Project(No.20yjky020)。
文摘Novel coronavirus pneumonia(COVID-19)is a highly pathogenic infectious disease caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Until now,the new crown pneumonia has caused hundreds of millions of people worldwide to be infected.Novel coronavirus pneumonia is still a high level of variation.Due to the high variability of COVID-19,there are already a large number of COVID-19 variant strains that are still at a high level of infection worldwide.Recently,WHO(WHO)released a new variant,"Mu"(μ,B.1.621)may be a high vaccine tolerance.This paper reviews the latest research progress of"Mu"virus strain in detail.
文摘To detect retrospectively the phenotype and stability of the E-protein gene in Japanese Encephalitis （JE） virus strain SA14-14-2 used in the live-attenuated JE vaccine prepears, the viral titer was titrated by plaque formation in BHK-21 cell cultures, and the neuro-virulence of viruses was assayed in mice with body weight of 12-14 g by intracerebral inoculation. Meanwhile, the total RNA of virus gene was extracted and amplified by RT-PCR with the designed primers, and then it was purified and cloned to the expression vector pGEM-T. The recombinant plasmid was purified and sequenced. It was found that the loss of viral titer of vaccines stored in -20℃ for longer than 10 years was less than 0.5 Lg PFU/ml. No mice inoculated intracerebrally showed signs of illness or even death. The size of plagues of the vaccine virus remained to be small, and the E genes of primary virus seed SA14-14-2 and the vaccines prepared at different years （1987-2001） were unchanged, in- cluding the 8 critical amino acid sites which were different from the parent wild virus strain SA14 and the related neuro-virulence. These results indicate that the genotypic and biological characteristics of the attenuated JE virus strain SA14-14-2 and its vaccines sion noted. prepared are quite stable without any reversion noted.
文摘The objective of this paper was to analyze the E2 genetic characterization of HB-DCZ strain of Bovine viral diaxrhca Virus （BVDV） which wcrc amplified by RT-PCR and isolated from China. The product of PCK was cloned into pMD18-T vector, and then transfected Escherichia Coli JMI00. The recombinant plasmids were amplified by PCR and were sequenced. From the nucleotide sequence of the amplified products, phylogenetie analyses were performed and genotypes or subgenotypes were identified. The results indicated that the E2 gene fragment of HB-DCZ strain contained 1277bp nucleotides, and had 89.4%, 70.7%, 97.6%, 68.9%, 67.2% sequence similarity with Osloss, OregonC24V, Changchun184, ZM195, NADL, respectively. In conclusion, HB-DCZ strain is closely related to BVDV Osloss, Changchun184, and belongs to subgenotype lb.
文摘Cucumber green mottle mosaic virus (CGMMV), a member of the Tobamovirus genus, causes a severe disease of cucurbits. In the Moscow region of Russian Federation, the incidence of infection on cucumber plants in greenhouses is high;however, the virus is poorly studied. In this work, the full-length genomes of two pathogenic MC-1 and MC-2 strains of CGMMV isolated from cucumber plants grown in greenhouses in the Moscow region and the attenuated VIROG-43M strain were sequenced. Comparison of VIROG-43M nucleotide sequence with those of the pathogenic strains revealed three missense mutations. Their role in attenuation is discussed. For the first time, in a number of trials conducted under laboratory conditions and in commercial greenhouses, the efficiency of the attenuated VIROG-43M strain as a biocontrol agent for cucumber plant protection resulting in significant yield gain was demonstrated. Phylogenetic analysis with 83 full-length CGMMV coat protein genes isolated in 16 different countries showed that Russian strains are related to isolates from Spain, Greece, USA and Israel.
文摘[ Objective ] The paper was to prevent the occurrence of broiler avian influenza virus HS subtype Re-8 strain effectively in the breeding process of broilers. [Method] The maternal antibodies of broilers in Beijing Baochen Hongwang farm were monitored. According to the disappearance law of maternal antibody, the optimal immune time of broiler avian influenza virus H5 subtype Re-8 strain was determined. [ Result] The maternal antibody level of 2-day-old broilers was relatively high, concentrated at 6 log2 -9 log2, and the antibody positive rate was 100%. The maternal antibody level of 8-day-old broilers concentrated at 4 log2 -6 log2, and the antibody positive rate was 100%. The maternal antibody level of 17-day-old broilers concentrated at 0 log2 -3 log2 , and the antibody positive rate was 0. The average maternal antibody level of 24 - 37 days old broilers was 〈 1 log2, and the antibody positive rate was 0. [ Conclusion ] Although the av- erage maternal antibody level of 8-day-old broilers was higher than 5 log2 , 20% of chickens was 4 log2, and maternal antibody could not protect the flock completely. Therefore, the best primary immunization day age of chicks against avian influenza virus was 8 - 10 days of age.
基金This project was supported by grants from the Chinese National Thirteenth Five Years Project in Science and Technology （No. 2017ZX10202201）, and Hubei Provincial Natural Science Foundation of China （No. 2018CFB206）.
文摘The mechanisms involved in virus-induced severe hepatitis have not been fully elucidated. In this study, we investigated the role of gamma delta T cell receptors （γδ） T cells in the pathogenesis of fulminant viral hepatitis （FVH） induced by murine hepatitis virus strain 3 （MHV-3）. The model of FVH was established by intraperitoneal injection of MHV-3 into Balb/cJ mice. The survival days of mice, and the serum levels of alanine aminotransferase （ALT） and aspartate aminotransferase （AST） were examined. The proportions of γδ T cells in blood, spleen and liver, and cytokines secreted by hepatic γδ T cells were analyzed by flow cytometry. The function of hepatic γδ T cells was examined by cytotoxicity assay. Balb/cJ mice died in 3 to 6 days post MHV-3 infection, with severe hepatic necrosis and significant augmentation of serum ALT and AST levels. The proportions of γδ T cells in blood, spleen and liver were significantly increased post MHV-3 infection, while those of the early activating molecule CD69-expressing γδ T cells and productions of cytokines tumor necrosis factor-alpha （TNF-α） and interferon-y （IFN-3,） increased remarkably in the liver. These highly activated liver γδ T cells were cytotoxic to MHV-3-infected hepatocytes in vitro and this effect of liver γδ T cells against hepatocytes might involve the TNF-α and IFN-γ pathway. These results demonstrated that γδ T cells might contribute to the pathogenesis of MHV-3-induced FVH through the effector cytokines TNF-α and IFN-γ. Key words： fulminant viral hepatitis; murine hepatitis virus strain 3; gamma delta T cell receptors T cells; tumor necrosis factor-a; interferon-α
文摘Two Marek's disease virus (MDV) field strains were isolated from chickens with tumors independently from Guangdong and Guangxi provinces, and it was confirmed that there were no co-infections with reticuloendotheliosis viruses (REV) in chicken embryo fibroblast cells (CEF) in indirect fluorescence antibody test (IFA) with REV-specific monoclonal antibodies. By dot blot hybridization and PCR of genomic DNA of MDV-infected CEF, it was indicated that LTR fragments of REV genome were integrated into genome of these two MDV field strains. To amplify and clone the integrated REV LTR with MDV sequence at the junction, 4 primers from REV LTR and 7 primers from MDV genome fragment with REV LTR insertion hot points were synthesized and 28 (4x7) pairs of primers (one from REV and another from MDV for each pair) were used in PCR while using the genomic DNA of both strains as the templates. The sequence data demonstrated that both recombinant field strains contained the same REV LTR inserted into MDV at the identical sites in US fragment of the genomes. From the above, it was speculated that both recombinant field MDVs were originated from a same recombinant virus and spread among chicken flocks in two provinces.
