Objective—To compare molecular typing methods
for the differentiation of Salmonella enterica serovar
Enteritidis phage type (PT) 4 isolates that allowed for
the determination of their genetic relatedness.
Sample Population—27 Salmonella Enteritidis PT 4
strains isolated in the United States and Europe.
Procedure—Several molecular typing methods were
performed to assess their ability to genetically differentiate
among Salmonella Enteritidis PT 4 isolates.
Results of pulse-field gel electrophoresis (PFGE),
repetitive polymerase chain reaction (PCR) assay, 16S
rRNA gene sequencing, random amplification of polymorphic
DNA (RAPD), PCR-restriction fragment
length polymorphism of 16S rRNA, and antimicrobial
susceptibility were evaluated.
Results—Compared with results for other techniques,
results for the RAPD typing method with the
RAPD1 primer reveal that it was the most discriminatory
fingerprinting technique, and it allowed us to
cluster Salmonella Enteritidis PT 4 isolates on the
basis of their genetic similarity.
Conclusions and Clinical Relevance—This study
revealed the value of RAPD with the RAPD1 primer as
a tool for epidemiologic investigations of Salmonella
Enteritidis PT 4. It can be used in conjunction with PFGE
and phage typing to determine the genetic relatedness
of Salmonella Enteritidis isolates involved in outbreaks
of disease. A reliable and highly discriminatory method
for epidemiologic investigations is critical to allow investigators
to identify the source of infections and consequently
prevent the spread of Salmonella Enteritidis
PT 4. ( Am J Vet Res 2004;65:538–543)
OBJECTIVE To determine titers of serum antibodies against 3 genotypes of bovine parainfluenza 3 virus (BPI3V) in unvaccinated ungulates in Alabama.
ANIMALS 62 cattle, goats, and New World camelids from 5 distinct herds and 21 captured white-tailed deer.
PROCEDURES Serum samples were obtained from all animals for determination of anti-BPI3V antibody titers, which were measured by virus neutralization assays that used indicator (reference) viruses from each of the 3 BPI3V genotypes (BPI3V-A, BPI3V-B, and BPI3V-C). The reference strains were recent clinical isolates from US cattle. Each sample was assayed in triplicate for each genotype. Animals with a mean antibody titer ≤ 2 for a particular genotype were considered seronegative for that genotype.
RESULTS Animals seropositive for antibodies against BPI3V were identified in 2 of 3 groups of cattle and the group of New World camelids. The geometric mean antibody titer against BPI3V-B was significantly greater than that for BPI3V-A and BPI3V-C in all 3 groups. All goats, captive white-tailed deer, and cattle in the third cattle group were seronegative for all 3 genotypes of the virus.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that BPI3V-A may no longer be the predominant genotype circulating among ungulates in Alabama. This may be clinically relevant because BPI3V is frequently involved in the pathogenesis of bovine respiratory disease complex, current vaccines contain antigens against BPI3V-A only, and the extent of cross-protection among antibodies against the various BPI3V genotypes is unknown.