An Attenuated Highly Pathogenic Chinese PRRS Viral Vaccine Confers Cross Protection to Pigs against Challenge with the Emerging PRRSV NADC30-Like Strain

A novel PRRSV strain was isolated in China that was genetically similar to the NADC30 strain which is reported to have spread throughout China. The objective of the present study was to evaluate the cross-protective efficacy of the live vaccine TJM-F92 in young pigs against challenge with a NADC30-like strain, HN201605. Twenty-five PRRSV-and antibody-free pigs were randomly divided into the following five groups: Vac/ChA, Unvac/ChA, Vac/ChB, Unvac/ChB and the mock.The pigs in groups Vac/ChA and Vac/ChB were inoculated intramuscularly with 1 mL TJM-F92(10^(5.0) TCID_(50)/mL). At28 days post vaccination(0 days post challenge), groups Vac/ChA and Unvac/ChA were inoculated intranasally with 10^(4.5) TCID_(50)/mL PRRSV strain TJ F3(2 mL/pig), while groups Vac/ChB and Unvac/Ch B were inoculated, using the same route, with the same dose of the NADC30-like strain HN201605 F3. Protective effects of the PRRSV strain were observed in all pigs in the Vac/ChA and Vac/ChB groups. Neither high fever nor signs of clinical disease were observed through the experiment in these groups, whereas pigs in Unvac/ChA group exhibited serious clinical symptoms, pathological lesions,and weight loss. In Unvac/ChB group, pigs developed milder clinical symptoms, which demonstrated that the NADC30-like strain HN201605 had moderate pathogenicity. The results suggest that the MLV vaccine strain TJM-F92 is an effective and safe vaccine candidate for use in China.

Development and evaluation of neutralizing antibodies for cross-protection against West Nile virus and Japanese encephalitis virus

Background:West Nile virus is a severe zoonotic pathogen that can cause severe central nervous system symptoms in humans and horses,and is fatal for birds,chickens and other poultry.With no specific drugs or vaccines available,antibody-based therapy is a promising treatment.This study aims to develop neutralizing antibodies against West Nile virus and assess their cross-protective potential against Japanese encephalitis virus.Methods:Monoclonal antibodies against WNV and JEV were isolated by hybridoma technology.The therapeutic efficacy of these antibodies was evaluated using a mouse model,and a humanized version of the monoclonal antibody was generated for potential human application.Results:In this study,we generated eight monoclonal antibodies that exhibit neutralizing activity against WNV.Their therapeutic effects against WNV were validated both in vivo and in vitro.Among these antibodies,C9-G11-F3 also exhibited cross-protective activity against JEV.We also humanized the antibody to ensure that it could be used for WNV infection treatment in humans.Conclusion:This study highlights the importance of neutralizing antibodies as a promising approach for pro-tection against West Nile virus infection and suggests their potential utility in the development of therapeutic interventions.

Genomic similarity and antibody-dependent enhancement of immune serum potentially affect the protective efficacy of commercial MLV vaccines against NADC30-like PRRSV

Porcine reproductive and respiratory syndrome(PRRS)is one of the most significant diseases affecting the pig industry worldwide.The PRRSV mutation rate is the highest among the RNA viruses.To date,NADC30-like PRRSV and highly pathogenic PRRSV(HP-PRRSV)are the dominant epidemic strains in China;however,commercial vaccines do not always provide sufficient cross-protection,and the reasons for insufficient protection are unclear.This study isolated a wild-type NADC30-like PRRSV,SX-YL1806,from Shaanxi Province.Vaccination challenge experiments in piglets showed that commercial modified live virus(MLV)vaccines provided good protection against HP-PRRSV.However,it could not provide sufficient protection against the novel strain SXYL1806.To explore the reasons for this phenomenon,we compared the genomic homology between the MLV strain and HP-PRRSV or NADC30-like PRRSV and found that the MLV strain had a lower genome similarity with NADC30-like PRRSV.Serum neutralization assay showed that MLV-immune serum slightly promoted the homologous HP-PRRSV replication and significantly promoted the heterologous NADC30-like PRRSV strain replication in vitro,suggesting that antibody-dependent enhancement(ADE)might also play a role in decreasing MLV protective efficacy.These findings expand our understanding of the potential factors affecting the protective effect of PRRSV MLV vaccines against the NADC30-like strains.

Seasonal influenza vaccination may mitigate the potential impact of an H5N1 pandemic

Seasonal influenza is a highly contagious, acute respiratory illness that affects people of all ages. The major pathogens, influenza A viruses, are classified into serologically defined antigenic subtypes of the hemagglutinin （HA） and neuraminidase （NA）. Of 16 identified HA and 9 NA subtypes, only H1N1 and H3N2 subtypes are now circulating among humans. Influenza vaccines have been available for over 60 years and well proven to be an effective public health intervention to control seasonal influenza epidemics. Seasonal influenza vaccines presently available, inactivated or split, contain the circulating strains of influenza A virus H3N2, H1N1 and influenza B virus. The composition of the vaccine is renewed semi-annually, as necessary, based on surveillance data.