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VIBROGEN-2

MULTIVALENT VACCINE TO PROTECT AGAINST VIBRIOSIS

DESCRIPTION

Vibrogen-2 bacterin comprises an aqueous suspension of formalin inactivated cultures of three strains of Vibrio anguillarum, without adjuvants or preservatives.

It immunises fish against the following Vibrio strains:

• Vibrio anguillarum serotype Ι - biotype Ι,
• Vibrio anguillarum serotype ΙΙ - biotype I and
• Vibrio anguillarum serotype ΙΙ - biotype IΙ, which is often referred to as Vibrio ordalii.

The vaccine is suitable for the immunisation of healthy fish against vibriosis. It has been shown in practice to be safe and effective for use with 1g or larger salmonid fish as well as with sea bass of at least 1g of wet weight.

In Greek marine aquaculture Vibrogen-2 is being used successfully for the immunisation of farmed sea bass in hatcheries as well as grow-out installations.

Sea bass (Dicentrarchus labrax)

ADMINISTRATION METHODS

Immersion (dip):  Each litre of Vibrogen-2 is diluted 1:10 in a suitable receptacle by the addition of 9 litres of holding water to give a bath of 10lt. Oxygen may advantageously be trickled through the vaccine dilution to reduce stress. The fish are netted in lots of approximately 0.5kg - 0.8kg, according to the handling net size, avoiding overcrowding or crushing. Holding water is drained from the fish, which are then immersed in the diluted bacterin for 30 sec. The fish are then removed from the dilution, drained and returned to the holding unit. The process is repeated until 100kg of fish are vaccinated for every diluted litre of Vibrogen-2. Then the dilution should be discarded. Diluted vaccine must not be stored.

Sea bass vaccination by immersion on the cages. Subsequent to fasting, groups of fish are enclosed in a tarpaulin where oxygen is provided. They are sedated in the tarpaulin by the addition of a light dose of anaesthetic (usually phenoxyethanol). The sedated fish are gradually netted out and put in the vaccine dilution for 30 sec. Then, they are lifted from the vaccine dilution (see photograph below), drained and released in an adjacent cage.

After the immersion time (30 sec) has lapsed, the fish are removed from the vaccine dilution. The use of perforated plastic bowls to contain the fish is recommended. Draining is fast, hence fish stress and losses of vaccine dilution are minimised.

Intraperitoneal injection:  When the fish are sufficiently large (>25g) the vaccine may be administered undiluted by injecting the fish intraperitoneally using automatic injection guns. Fish are anaesthetised until completely immobile and then handled individually. 0.1ml of Vibrogen-2 is injected in the abdominal area of each fish held with the ventral side up and the head away from the operator΄s body. The needle is inserted into the peritoneal cavity at a 45^o angle to a depth of approximately 0.5 cm.

Different types and models of injectors are available, either fixed or adjustable dose, stainless steel, or plastic.
Luer lock vaccination needles for veterinary use are adjusted on to these injection “guns”.

Bath (transportation method):  The fry (1g-5g) remain in the tank either in the hatchery or on the transportation vehicle or boat while the water level is gradually reduced until the maximum sustainable density is reached under constant aeration. Diluted oxygen levels should remain at about 8ppm. A light dose of anaesthetic may be added to the water to reduce stress if necessary. Vibrogen-2 vaccine is added to the tank 1:500, that is, 2lt./m³ and the fish are left to swim in this vaccine dilution for at least 60-100 minutes prior to release or restoration of the water level in the tank.

PRECAUTIONS

Vaccinate healthy fish, which are not under stress. A short fasting period must precede vaccination. Vaccination is not indicated when fish are suffering a disease outbreak or have been through recent severe handling or any other stress.

Vaccination must be performed in a disease free environment and precede exposure to disease or transfer to a disease prone site by about two weeks when water temperatures range around 15^oC (200 degree-days). Smaller intervals are required for the establishment of immunity at higher water temperatures (e.g. 10 days at 20^oC).

At dip vaccination, the temperature difference between vaccinal dilution and holding water should not exceed 2° C.

There are no contra-indications or unwanted side-effects reported for Vibrogen-2.

Vibrogen-2 vaccine does not react with nor is affected by anaesthetics or pharmaceutical substances, such as antibiotics, normally used on farmed fish.

STORAGE

Store the bacterin between 2^o and 7^o C. Do not freeze. Do not leave in ambient temperature for several days. Protect from light, especially the direct exposure to the sun. Use entire contents the same day when first opened.

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