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Secondary infection with Streptococcus suis serotype 7 increases the virulence of highly pathogenic porcine reproductive and respiratory syndrome virus in pigs.

Xu M, Wang S, Li L, Lei L, Liu Y, Shi W, Wu J, Li L, Rong F, Xu M, Sun G, Xiang H, Cai X - Virol. J. (2010)

Bottom Line: To determine whether PRRSV-SS7 coinfection was the cause of the PHFS outbreak, we evaluated the pathogenicity of PRRSV and/or SS7 in a pig model of single and mixed infection.Respiratory disease, diarrhea, and anorexia were observed in all infected pigs.HP-PRRSV infection increased susceptibility to SS7 infection, and coinfection of HP-PRRSV with SS7 significantly increased the pathogenicity of SS7 to pigs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Swine Infectious Diseases, National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, CAAS, Harbin, China.

ABSTRACT

Background: Porcine reproductive and respiratory syndrome virus (PRRSV) and Streptococcus suis are common pathogens in pigs. In samples collected during the porcine high fever syndrome (PHFS) outbreak in many parts of China, PRRSV and S. suis serotype 7 (SS7) have always been isolated together. To determine whether PRRSV-SS7 coinfection was the cause of the PHFS outbreak, we evaluated the pathogenicity of PRRSV and/or SS7 in a pig model of single and mixed infection.

Results: Respiratory disease, diarrhea, and anorexia were observed in all infected pigs. Signs of central nervous system (CNS) disease were observed in the highly pathogenic PRRSV (HP-PRRSV)-infected pigs (4/12) and the coinfected pigs (8/10); however, the symptoms of the coinfected pigs were clearly more severe than those of the HP-PRRSV-infected pigs. The mortality rate was significantly higher in the coinfected pigs (8/10) than in the HP-PRRSV- (2/12) and SS7-infected pigs (0/10). The deceased pigs of the coinfected group had symptoms typical of PHFS, such as high fever, anorexia, and red coloration of the ears and the body. The isolation rates of HP-PRRSV and SS7 were higher and the lesion severity was greater in the coinfected pigs than in monoinfected pigs.

Conclusion: HP-PRRSV infection increased susceptibility to SS7 infection, and coinfection of HP-PRRSV with SS7 significantly increased the pathogenicity of SS7 to pigs.

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Related in: MedlinePlus

PRRSV RNA. (a) PRRSV RNA levels in the lungs of all pigs in HP-PRRSV-infected and coinfected groups either after necropsy or death. The data from the coinfected group at 14 days post-inoculation (DPI) is the mean value of 8 pigs of the coinfected group that died between 10 and 15 DPI; no pigs from the coinfected group were necropsied on 21 DPI. (b) The PRRSV RNA levels in the brains of HP-PRRSV-infected and coinfected pigs.
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Figure 4: PRRSV RNA. (a) PRRSV RNA levels in the lungs of all pigs in HP-PRRSV-infected and coinfected groups either after necropsy or death. The data from the coinfected group at 14 days post-inoculation (DPI) is the mean value of 8 pigs of the coinfected group that died between 10 and 15 DPI; no pigs from the coinfected group were necropsied on 21 DPI. (b) The PRRSV RNA levels in the brains of HP-PRRSV-infected and coinfected pigs.

Mentions: The control and SS7-infected pigs did not contain PRRSV RNA in the lungs and brain. However, all pigs in the HP-PRRSV-infected and coinfected groups contained PRRSV in the lungs, and 4 pigs in the coinfected group and 1 pig in HP-PRRSV-infected group contained PRRSV in the brain. The lungs of HP-PRRSV-infected and coinfected pigs contained similar amount of PRRSV RNA; however, the amount of PRRSV RNA in the brain of coinfected pigs was significantly higher (P < 0.01) than that in HP-PRRSV-infected pigs. The PRRSV levels in the lung and brain are shown in Figure 4.


Secondary infection with Streptococcus suis serotype 7 increases the virulence of highly pathogenic porcine reproductive and respiratory syndrome virus in pigs.

Xu M, Wang S, Li L, Lei L, Liu Y, Shi W, Wu J, Li L, Rong F, Xu M, Sun G, Xiang H, Cai X - Virol. J. (2010)

PRRSV RNA. (a) PRRSV RNA levels in the lungs of all pigs in HP-PRRSV-infected and coinfected groups either after necropsy or death. The data from the coinfected group at 14 days post-inoculation (DPI) is the mean value of 8 pigs of the coinfected group that died between 10 and 15 DPI; no pigs from the coinfected group were necropsied on 21 DPI. (b) The PRRSV RNA levels in the brains of HP-PRRSV-infected and coinfected pigs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927530&req=5

Figure 4: PRRSV RNA. (a) PRRSV RNA levels in the lungs of all pigs in HP-PRRSV-infected and coinfected groups either after necropsy or death. The data from the coinfected group at 14 days post-inoculation (DPI) is the mean value of 8 pigs of the coinfected group that died between 10 and 15 DPI; no pigs from the coinfected group were necropsied on 21 DPI. (b) The PRRSV RNA levels in the brains of HP-PRRSV-infected and coinfected pigs.
Mentions: The control and SS7-infected pigs did not contain PRRSV RNA in the lungs and brain. However, all pigs in the HP-PRRSV-infected and coinfected groups contained PRRSV in the lungs, and 4 pigs in the coinfected group and 1 pig in HP-PRRSV-infected group contained PRRSV in the brain. The lungs of HP-PRRSV-infected and coinfected pigs contained similar amount of PRRSV RNA; however, the amount of PRRSV RNA in the brain of coinfected pigs was significantly higher (P < 0.01) than that in HP-PRRSV-infected pigs. The PRRSV levels in the lung and brain are shown in Figure 4.

Bottom Line: To determine whether PRRSV-SS7 coinfection was the cause of the PHFS outbreak, we evaluated the pathogenicity of PRRSV and/or SS7 in a pig model of single and mixed infection.Respiratory disease, diarrhea, and anorexia were observed in all infected pigs.HP-PRRSV infection increased susceptibility to SS7 infection, and coinfection of HP-PRRSV with SS7 significantly increased the pathogenicity of SS7 to pigs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Swine Infectious Diseases, National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, CAAS, Harbin, China.

ABSTRACT

Background: Porcine reproductive and respiratory syndrome virus (PRRSV) and Streptococcus suis are common pathogens in pigs. In samples collected during the porcine high fever syndrome (PHFS) outbreak in many parts of China, PRRSV and S. suis serotype 7 (SS7) have always been isolated together. To determine whether PRRSV-SS7 coinfection was the cause of the PHFS outbreak, we evaluated the pathogenicity of PRRSV and/or SS7 in a pig model of single and mixed infection.

Results: Respiratory disease, diarrhea, and anorexia were observed in all infected pigs. Signs of central nervous system (CNS) disease were observed in the highly pathogenic PRRSV (HP-PRRSV)-infected pigs (4/12) and the coinfected pigs (8/10); however, the symptoms of the coinfected pigs were clearly more severe than those of the HP-PRRSV-infected pigs. The mortality rate was significantly higher in the coinfected pigs (8/10) than in the HP-PRRSV- (2/12) and SS7-infected pigs (0/10). The deceased pigs of the coinfected group had symptoms typical of PHFS, such as high fever, anorexia, and red coloration of the ears and the body. The isolation rates of HP-PRRSV and SS7 were higher and the lesion severity was greater in the coinfected pigs than in monoinfected pigs.

Conclusion: HP-PRRSV infection increased susceptibility to SS7 infection, and coinfection of HP-PRRSV with SS7 significantly increased the pathogenicity of SS7 to pigs.

Show MeSH
Related in: MedlinePlus