United States of America, As Represented by the Secretary of Agriculture

University of Connecticut

Universidad Del Pais Vasco/euskal Herriko Univertsitatea (upv-ehu)

Vivian O'Donnell

Manuel V Borca

Lauren G Holinka-Patterson

Douglas P Gladue

Guillermo R Risatti

Luis Leandro Rodriguez

Peter William Krug

Guillermo S Risatti

Jose Nieva

Douglas Gladu

The role of a specific E2 region containing a putative fusion peptide (FP) sequence was evaluated. FPs critically contribute to the interaction between proteins and the membrane system of the host cell. Reverse genetics utilizing a full-length infectious clone of the highly virulent CSFV strain Brescia (BICv) was used to evaluate how amino acid substitutions within this region of E2 may affect replication of BICv in cell cultures and affect virus virulence in swine. Interestingly, mutated virus FPi.c was completely attenuated when inoculated intranasally at a dose of 10TCID50 in swine. Importantly, animals infected with FPi.c virus were protected against the virulent challenge with Brescia virus at 3 and 28 days after vaccination. Protection was evidenced by absence of clinical signs related with CSF as well as the absence of viremia produced by the challenge virulent virus.

Live attenuated classical swine fever vaccine based in genetic manipulation of a putative fusion peptide area in the virus structural glycoprotein E2

African swine fever virus (ASFV) is the etiological agent of a contagious, often lethal viral disease of domestic pigs. The control of African Swine Fever (ASF) has been hampered by the unavailability of vaccines. Experimental vaccines have been derived from naturally occurring, cell culture-adapted, or genetically modified live attenuated ASFVs; however, these vaccines are only successful when protecting against homologous viruses. We have constructed a recombinant &#x394;9GL/&#x394;UK virus derived from the highly virulent ASFV Georgia 2007 (ASFV-G) isolate by deleting the specific virulence-associated 9GL (B119L) and the UK (DP96R) genes. In vivo, ASFV-G &#x394;9GL/&#x394;UK administered intramuscularly to swine even at relatively high doses (10HAD) does not induce disease. Importantly, animals infected with 10or 10HADare solidly protected against the presentation of clinical disease when challenged at 28 days post infection with the virulent parental strain Georgia 2007.

Rationally developed african swine fever attenuated virus strain protects against challenge with parental virus georgia 2007 isolate

African swine fever virus (ASFV) is the etiological agent of a contagious and often lethal viral disease of domestic pigs. Control of ASF has been hampered by the unavailability of vaccines. Experimental vaccines have been derived from naturally occurring, cell culture-adapted, or genetically modified live attenuated ASFVs; however, these vaccines are only successful when protecting against homologous viruses. Among viral genes reported to be involved in virulence are components of the multi gene family (MGF). Here we report the construction of a recombinant &#x394;MGF virus derived from the highly virulent ASFV Georgia 2007 (ASFV-G) isolate. In vivo, ASFV-G &#x394;MGF administered intramuscularly (IM) to swine at either 10or 10HADare completely attenuated; the inoculated animals are completely asymptomatic. Animals infected with 10or 10HAD50 of ASFV-G &#x394;MGF are protected against the presentation of clinical disease when challenged at 28 days post infection with the virulent parental strain Georgia 2007.

Attenuated African swine fever virus vaccine based in the deletion of MGF genes

We have developed an ASFV Georgia strain adapted to grow in Vero cell line. The resulting virus, ASF-GVAV, efficiently grows in Vero cells although it still is able to significantly replicate in primary cell cultures of swine macrophages. ASF-GVAV virus was successfully used as parental virus to develop several recombinant ASF viruses. The development of an ASFV adapted to grow in an established cell line is a significant advance for research and development of vaccine candidate strains using genetic manipulation based in the process of homologous recombination. The GVAVS can be utilized as a basis for large scale production of ASF vaccines.

African swine fever virus georgia strain adapted to efficiently grow in the vero cell line

African swine fever virus (ASFV) is the etiological agent of a contagious and often lethal viral disease of domestic pigs that has significant economic consequences for swine breeding. Control of ASF has been hampered by the unavailability of vaccines. Recombinant viruses harboring engineered deletions of specific virulence-associated genes induce solid protection against the challenge with parental viruses. Here we report the construction of a recombinant &#x394;9GL virus derived from the highly virulent ASFV Georgia 2007 (ASFV-G) isolate. In vivo, ASFV-G &#x394;9GL administered intramuscularly (IM) to swine at relatively high doses (10HAD) retains a virulent phenotype practically indistinguishable from the parental virus. Conversely, at low IM doses (10or 10HAD), ASFV-G &#x394;9GL does not induce disease. Importantly, animals infected with 10HADare protected against the presentation of clinical disease when challenge at 28 days post infection with the virulent parental strain Georgia 2007.

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Old Saybrook, CT, United States of America

Vivian O'Donnell