RNA Nanovaccine Protects against White Spot Syndrome Virus in Shrimp

In the last 15 years, crustacean fisheries have experienced billions of dollars in economic losses, primarily due to viral diseases caused by such pathogens as white spot syndrome virus (WSSV) in the Pacific white shrimp Litopenaeus vannamei and Asian tiger shrimp Penaeus monodon. To date, no effective measures are available to prevent or control disease outbreaks in these animals, despite their economic importance. Recently, double-stranded RNA-based vaccines have been shown to provide specific and robust protection against WSSV infection in cultured shrimp. However, the limited stability of double-stranded RNA is the most significant hurdle for the field application of these vaccines with respect to delivery within an aquatic system. Polyanhydride nanoparticles have been successfully used for the encapsulation and release of vaccine antigens. We have developed a double-stranded RNA-based nanovaccine for use in shrimp disease control with emphasis on the Pacific white shrimp L. vannamei. Nanoparticles based on copolymers of sebacic acid, 1,6-bis(p-carboxyphenoxy)hexane, and 1,8-bis(p-carboxyphenoxy)-3,6-dioxaoctane exhibited excellent safety profiles, as measured by shrimp survival and histological evaluation. Furthermore, the nanoparticles localized to tissue target replication sites for WSSV and persisted through 28 days postadministration. Finally, the nanovaccine provided ~80% protection in a lethal WSSV challenge model. This study demonstrates the exciting potential of a safe, effective, and field-applicable RNA nanovaccine that can be rationally designed against infectious diseases affecting aquaculture.

[Intrauterine diagnosis of holoprosencephaly]

The internal and external interorbital diameters are measured during pregnancy. A case of holoprosencephaly was diagnosed via ultrasound on the basis of the reduction of both diameters.

["Maturation" of the intestine during pregnancy: successive observation with ultrasound]

The echographic images of the fetal intestines during the final 20 weeks of pregnancy are described. A comparison with the biparietal and abdominal diameter as well as with the echogenicity of the placenta is made. The sonographic images of the fetal intestines are divided into four grades, the last two appearing in the mature foetus only.