Working safely with vaccinia virus: laboratory technique and the role of vaccinia vaccination

Genomic identification of human vaccinia virus keratoconjunctivitis and its importance as a laboratory-acquired infection

Context:

Vaccinia virus (VACV) is a member of orthopoxvirus genus of the family Poxviridae. VACVs are enveloped, double-stranded DNA viruses. Several species of this family, for example, molluscum contagiosum, smallpox, deerpox, horsepox, rabbitpox, and VACVs may cause conjunctivitis.

Aims:

Given the high incidence of keratoconjunctivitis in Iran (approximately 3.6%–53.9%) and insufficient clinical diagnostic measures, laboratory tests for detection of its causes and determination of accurate keratoconjunctivitis/conjunctivitis prevalence due to different pathogens are essential.

Settings and Design:

In this research, conjunctival samples collected from 100 patients with keratoconjunctivitis signs were referred to an eye hospital of Iran.

Subjects and Methods:

After DNA extraction, polymerase chain reaction (PCR) was carried out for detection of VACV. PCR-positive products were further subjected to DNA sequencing.

Statistical Analysis Used:

The results were analyzed using Chi-square test.

Results:

In this study, 28% of the samples were positive and a statistically significant relationship obtained between working in medical or research laboratories and VACV prevalence (P < 0.05).

Conclusions:

This study showed a high rate of VACV keratoconjunctivitis, and therefore, further studies for its prevention and control are necessary.

Evidence-based biosafety: a review of the principles and effectiveness of microbiological containment measures

We examined the available evidence on the effectiveness of measures aimed at protecting humans and the environment against the risks of working with genetically modified microorganisms (GMOs) and with non-GMO pathogenic microorganisms. A few principles and methods underlie the current biosafety practice: risk assessment, biological containment, concentration and enclosure, exposure minimization, physical containment, and hazard minimization. Many of the current practices are based on experience and expert judgment. The effectiveness of biosafety measures may be evaluated at the level of single containment equipment items and procedures, at the level of the laboratory as a whole, or at the clinical-epidemiological level. Data on the containment effectiveness of equipment and laboratories are scarce and fragmented. Laboratory-acquired infections (LAIs) are therefore important for evaluating the effectiveness of biosafety. For the majority of LAIs there appears to be no direct cause, suggesting that failures of biosafety were not noticed or that containment may have been insufficient. The number of reported laboratory accidents associated with GMOs is substantially lower than that of those associated with non-GMOs. It is unknown to what extent specific measures contribute to the overall level of biosafety. We therefore recommend that the evidence base of biosafety practice be strengthened.

Vaccinia virus entry, exit, and interaction with differentiated human airway epithelia

Variola virus, the causative agent of smallpox, enters and exits the host via the respiratory route. To better understand the pathogenesis of poxvirus infection and its interaction with respiratory epithelia, we used vaccinia virus and examined its interaction with primary cultures of well-differentiated human airway epithelia. We found that vaccinia virus preferentially infected the epithelia through the basolateral membrane and released viral progeny across the apical membrane. Despite infection and virus production, epithelia retained tight junctions, transepithelial electrical conductance, and a steep transepithelial concentration gradient of virus, indicating integrity of the epithelial barrier. In fact, during the first four days of infection, epithelial height and cell number increased. These morphological changes and maintenance of epithelial integrity required vaccinia virus growth factor, which was released basolaterally, where it activated epidermal growth factor 1 receptors. These data suggest a complex interaction between the virus and differentiated airway epithelia; the virus preferentially enters the cells basolaterally, exits apically, and maintains epithelial integrity by stimulating growth factor receptors.

Ocular vaccinia infection in laboratory worker, Philadelphia, 2004

We report a case of ocular vaccinia infection in an unvaccinated laboratory worker. The patient was infected by a unique strain used in an experiment performed partly outside a biosafety cabinet. Vaccination should continue to be recommended, but laboratories with unvaccinated workers should also implement more stringent biosafety practices.