The Autographa californica M nucleopolyhedrovirus (AcMNPV) encodes a gene (open reading frame 32) with homology to vertebrate and invertebrate fibroblast growth factors (fgfs), key regulators of developmental processes affecting the growth, differentiation, and migration of many cell types. We studied the temporal regulation of the AcMNPV fgf, vfgf, by Northern (RNA) blot hybridization; vfgf was transcribed as a 0.6-kb mRNA at early times but as part of a 1.4-kb bicistronic mRNA at late times. The product of vfgf, vFGF, exhibited a number of characteristics that have also been demonstrated for other FGF homologs. vFGF had strong affinity to heparin, a property important for FGF signaling via an FGF receptor. vFGF was secreted into the extracellular fluid when expressed in insect cells, suggesting that it acts as an extracellular ligand. Finally, vFGF was able to stimulate migration of several different types of insect cells. We discuss how this activity may be important for its function during virus infection.

The fibroblast growth factor (vfgf) gene encoded by Autographa californica M nucleopolyhedrovirus (AcMNPV) has been shown to share functional properties with cellular fgfs; it is a secreted protein, binds heparin, and stimulates motility of insect cells. We previously reported that viruses containing or lacking vfgf produced similar yields of budded virus and had similar kinetics of viral DNA and protein syntheses in cultured cells. In this study, we characterized these viruses in two permissive hosts, Spodoptera frugiperda and Trichoplusia ni, using two insect developmental stages and two infection routes, by feeding and intrahemocoelic injection. In addition, we constructed an AcMNPV bacmid overexpressing vfgf under polyhedrin promoter control and characterized it in both cell culture and insects. Deletion of vfgf had no effect on the infectivity of AcMNPV. However, lack of vfgf delayed the time of death in two host species when the virus was delivered by feeding but not by intrahemocoelic injection. The virus overexpressing vfgf produced less budded virus than the control virus in cultured cells. In insect bioassays, the infectivity of this virus was greater than that of the parental virus in both insect species and significantly accelerated time of death of both hosts tested. Our results suggest that the AcMNPV vfgf may play a role in dissemination of virus infection from the midgut in the insect species tested.

Baculoviruses encode fibroblast growth factor (vfgf) homologs whose function during virus infection is unknown. We constructed a recombinant bacmid of Autographa californica M nucleopolyhedrovirus (AcMNPV) lacking a functional vfgf and characterized it in two insect cell lines. The kinetics of budded virus production were similar in the parental and vfgf-deficient viruses in both cell lines at both high and low multiplicities of infection. In addition, no obvious differences were observed between the mutant and parental viruses in protein or DNA synthesis. Finally, coinfection of vfgf-containing and -deficient viruses and passage for several generations did not reveal a consistent growth advantage for either virus.

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A colony polymerase chain reaction (PCR) technique was applied with an established Fung's double tube (FDT) method for rapid detection and confirmation of Clostridium perfringens. Published sequences of PCR primers for C. perfringens alpha toxin gene were used and PCR conditions were optimized. From the detection of C. perfringens by FDT tube to the confirmation by a colony PCR assay took as short as 16–18 h. The method was applied to 147 isolates of anaerobic sulfite reducing bacteria isolated from foods, sewages and animal clinical specimens. The results were compared with standard methods for the confirmation of C. perfringens. Of those 147 suspected isolates, 97 and 99 were confirmed as C. perfringens by standard methods and the colony PCR technique, respectively. We found the developed method simple, rapid, cost‐effective, and most importantly, very reliable for the detection and confirmation of C. perfringens. PRACTICAL APPLICATIONS With Fung's double tube method and a colony polymerase chain reaction technique, a completed determination of Clostridium perfringens contamination can be accomplished within 16–18 h. This saves at least 2–3 days when compared with standard methods. Moreover, it minimizes the cost and labor needed since an anaerobic chamber as well as steps of Gram staining and biochemical testing can be avoided. The developed method is a powerful tool and an alternative for the enumeration of C. perfringens. It can be applied to samples from various sources and highly reliable results are expected. Most microbiological laboratories have a thermocycler and reagents as parts of their basic instruments. Therefore, the developed method can be easily applied without massive investment.